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Materiales Funcionales Nanoestructurados


Grupos de Investigación

  • Materiales Nanoestructurados y Microestructura  (web).
    Responsable del Grupo: Dra. Asunción Fernández Camacho
     
  • Nanotecnología en Superficies y Plasma (web).
    Responsable del Grupo: Dr. Ángel Barranco Quero
     
  • Materiales para la Bioingeniería y Regeneración Tisular.
    Responsable del Grupo: Dra. María Aránzazu Díaz Cuenca
     
  • Tribología y Protección de Superficies.
    Responsable del Grupo: Dr. Juan Carlos Sánchez López


Profesores de Investigación

Espinós Manzorro, Juan Pedro

Profesor de Investigación

CSIC


✉ jpespinos@icmse.csic.es
☎ 954 48 95 30 ✆ 446130
ORCID 0000-0002-3053-0841

Fernández Camacho, Asunción

Profesora de Investigación

CSIC


✉ asuncion@icmse.csic.es
☎ 954 48 95 31 ✆ 446131
ORCID 0000-0002-7487-7054


Investigadores Científicos

Barranco Quero, Angel

Investigador Científico

CSIC


✉ angel.barranco@csic.es
☎ 954 48 95 96 ✆ 446196
ORCID 0000-0002-8099-7669

Sánchez López, Juan Carlos

Investigador Científico

CSIC


✉ jcslopez@icmse.csic.es
☎ 954 48 95 79 ✆ 446179
ORCID 0000-0002-3490-6455

Tribología y Protección de Superficies

Yubero Valencia, Francisco

Investigador Científico

CSIC


✉ yubero@icmse.csic.es
☎ 954 48 95 97 ✆ 446197
ORCID 0000-0001-5107-9490


Científicos Titulares

Aparicio Rebollo, Francisco Javier

Científico Titular

CSIC


✉ fjaparicio@icmse.csic.es
☎ 954 13 92 26 ✆ 446159
ORCID 0000-0003-2010-1223

Borrás Martos, Ana Isabel

Científica Titular

CSIC


✉ anaisabel.borras@icmse.csic.es
☎ 954 48 95 92 ✆ 446192
ORCID 0000-0001-8799-2054

Díaz Cuenca, María Aránzazu

Científica Titular

CSIC


✉ aranzazu@icmse.csic.es
☎ 954 48 95 42 ✆ 446142
ORCID 0000-0002-5790-4452

Materiales para la Bioingeniería y Regeneración Tisular

Palmero Acebedo, Alberto

Científico Titular

CSIC


✉ alberto.palmero@icmse.csic.es
☎ 954 48 96 20 ✆ 446120
ORCID 0000-0002-1100-6569

Rojas Ruiz, Cristina

Científica Titular

CSIC


✉ tcrojas@icmse.csic.es
☎ 954 48 96 25 ✆ 446125
ORCID 0000-0001-7684-2421

Tribología y Protección de Superficies

Sánchez Valencia, Juan Ramón

Científico Titular

CSIC


✉ jrsanchez@icmse.csic.es
☎ 954 55 20 80 ✆ 446186
ORCID 0000-0003-2493-4433


Profesores Titulares

Alvarez Molina, Rafael

Profesor Titular

Universidad de Sevilla


✉ rafael.alvarez@icmse.csic.es
☎ 954 48 95 48 ✆ 446148
ORCID 0000-0002-1749-4946

Gómez Ramírez, Ana María

Profesora Titular

Universidad de Sevilla


✉ anamaria.gomez@icmse.csic.es
✆ 446177
ORCID 0000-0003-4402-7515

López Santos, María del Carmen

Profesora Titular

Universidad de Sevilla


✉ mclopez@icmse.csic.es
☎ 954 13 92 26 ✆ 446159
ORCID 0000-0001-8782-7331


Profesores "Ad Honorem"

Rodríguez González-Elipe, Agustín

Profesor "Ad Honorem"

CSIC


✉ arge@icmse.csic.es
☎ 954 48 95 28 ✆ 446128
ORCID 0000-0002-6417-1437


Investigadores Honorarios

Cotrino Bautista, José

Investigador Honorario

Universidad de Sevilla


✉ cotrino@us.es
☎ 954 48 95 77 ✆ 446177
ORCID 0000-0001-6538-2087


Doctores Contratados

Budagosky Marcilla, Jorge Alejandro

Doctor Contratado

Universidad de Sevilla


✉ jorge.budagosky@icmse.csic.es

ORCID 0000-0003-0094-3490

Contreras Bernal, Lidia

Doctora Contratada

Universidad de Sevilla


✉ lidia.contreras@icmse.csic.es

ORCID 0000-0002-0261-0828

Fortio Godinho, Vanda Cristina

Doctora Contratada

CSIC


✉ godinho@icmse.csic.es
☎ 954 13 92 26 ✆ 446159
ORCID 0000-0003-1829-6674

Gil Rostra, Jorge

Doctor Contratado

CSIC


✉ jorge.gil@icmse.csic.es
☎ 954 13 92 26 ✆ 446159
ORCID 0000-0002-4459-4088

López Flores, Victor

Doctor Contratado

Universidad de Sevilla


✉ victor.lopez@icmse.csic.es

ORCID 0000-0002-6319-5971

Luque Centeno, José Manuel

Doctor Contratado

CSIC


✉ jmanuel.luque@icmse.csic.es


Mishra, Hari Krishna

Doctor Contratado

CSIC


✉ hari.krishna@icmse.csic.es
☎ 954 13 92 36 ✆ 446171

Oliva Ramírez, Manuel

Doctor Contratado

Universidad de Sevilla


✉ manuel.oliva@icmse.csic.es
☎ 954 13 92 25 ✆ 446158
ORCID 0000-0003-0249-377X


Personal Investigador en Formación

Acosta Rivera, María Hiedra

Investigadora en Formación

CSIC


✉ hiedra.acosta@icmse.csic.es
☎ 954 13 92 36 ✆ 446171

Cabrera Fernández, Alberto

Investigador en Formación

Universidad de Sevilla


✉ acabrera5@us.es


Materiales para la Bioingeniería y Regeneración Tisular

Carmo Delcán, Álvaro

Investigador en Formación

CSIC


✉ alvaro.carmo@icmse.csic.es


Castillo Seoane, Javier

Investigador en Formación

CSIC


✉ javier.castillo@icmse.csic.es

ORCID 0000-0002-8949-3010

Czermak Álvarez, Triana

Investigadora en Formación

CSIC


✉ triana.czermak@icmse.csic.es
☎ 954 13 92 36 ✆ 446171

Del Moral Jalón, Jaime

Investigador en Formación

CSIC


✉ jaime.delmoral@icmse.csic.es

ORCID 0000-0003-3608-8801

Delgado Álvarez, Juan

Investigador en Formación

CSIC


✉ juan.delgado@csic.es


García Casas, Xabier

Investigador en Formación

CSIC


✉ xabier.garcia@icmse.csic.es
☎ 954 13 92 06 ✆ 446110
ORCID 0000-0002-7165-3952

Jumilla Núñez, Darío

Investigador en Formación

CSIC


✉ dario.jumilla@icmse.csic.es
☎ 954 13 92 36 ✆ 446171

Marín Meana, Servando

Investigador en Formación

Universidad de Sevilla


✉ servando.marin@icmse.csic.es

ORCID 0000-0001-6467-4344

Martínez Olaizola, Mikel

Investigador en Formación

CSIC


✉ mikel.martinez@icmse.csic.es
☎ 954 13 92 36 ✆ 446171

Megías Sánchez, Adrián

Investigador en Formación

Universidad de Sevilla





Montes Montañez, Laura

Investigadora en Formación

CSIC


✉ laura.montes@icmse.csic.es
☎ 954 13 92 36 ✆ 446171

Moreno Martínez, Gloria Patricia

Investigadora en Formación

CSIC


✉ gloria.moreno@icmse.csic.es


Núñez Gálvez, Fernando

Investigador en Formación

CSIC


✉ fernando.ngalvez@icmse.csic.es
☎ 954 13 92 26 ✆ 446159

Orozco Corrales, Noel

Investigador en Formación

CSIC


✉ noe.orozco@icmse.csic.es

ORCID 0000-0002-8104-7737

Parra Montero, Claudia Beth

Investigadora en Formación

Universidad de Sevilla


✉ claudia.parra@icmse.csic.es


Ruiz Martín, Mateo

Investigador en Formación

Universidad de Sevilla




ORCID 0009-0009-4219-7116


Personal Técnico

Rico Gavira, Victor Joaquín

Técnico Superior Especializado OPIs

CSIC


✉ victor@icmse.csic.es

ORCID 0000-0002-5083-0390


Personal Técnico Contratado

De Tena Álvarez, Iru Nerea

Project Manager

CSIC


✉ nerea.detena@icmse.csic.es
☎ 954 48 95 92 ✆ 446192

Hufschmidt, Dirk

Técnico

CSIC


✉ dirk@icmse.csic.es
✆ 446103

Moreno de la Vega, José Manuel

Técnico

CSIC


✉ josemanuel.moreno@icmse.csic.es


Tribología y Protección de Superficies

Sánchez Villa, Melania

Técnico en Formación

CSIC


✉ melania.sanchez@icmse.csic.es
☎ 954 13 92 36 ✆ 446171

Advancing supercapacitors with plasma-designed multifunctional hybrid materials


28-06-2024 / 28-06-2027



Investigador Principal: Juan Ramón Sánchez Valencia
Organismo Financiador: Ministerio de Ciencia, Innovación y Universidades "Proyectos de Colaboración Internacional"
Código: PCI2024-153451 Programa Internacional: M-ERA Net COFUND

Equipo de Investigación: Ángel Barranco Quero, Ana Isabel Borrás Martos, Vanda Fortio Godinho, Victor Joaquín Rico Gavira, Jorge Gil Rostra, Francisco Javier Aparicio Rebollo, Juan Pedro Espinós Manzorro




Current rechargeable energy storage devices face important drawbacks, including long-term raw materials availability, life-cycle, high prices, and safety issues. Due to their fast discharge capabilities and long-term life cycle, supercapacitors are potential candidates for future energy storage. However, supercapacitors must overcome technical problems with designing electrodes and electrolytes, stability, energy density, and attaining industry standards.
ANGSTROM proposes an environmentally friendly plasma-enabled approach for developing advanced materials for supercapacitors, comprising vertical nanocarbon and highly porous active materials, the latter consisting of covalent organic frameworks or a new type of “a la carte” conformal porous metal oxides. The multidisciplinary and ambitious methodology and unique expertise will make it possible to surpass the state-of-the-art supercapacitors with superior capacitive storage, high energy density, and potential for reusability.
The ANGSTROM consortium includes three international academic and one industrial partner. The Spanish National Research Council (CSIC), Spain, coordinates the consortium. The other academic partners are the Jožef Stefan Institute (JSI), Slovenia, and The Central European Institute of Technology (CEITEC), and the industrial company is IQS nano, these two latter from Czechia.

Programa Internacional: M-ERA Net COFUND

https://angstrom-meranet.eu/


Dispositivos fotónicos y optoelectrónicos de alta estabilidad basados en perovskitas de haluro mediante tecnologías de vacío y plasma


01-09-2023 / 31-08-2026



Investigador Principal: Angel Barranco Quero / Juan Ramón Sánchez Valencia
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: PID2022-143120OB-I00

Equipo de Investigación: Vanda Fortio, Victor López, José Cotrino, Ricardo Molina (IQAC), Victor J. Rico, Juan Pedro Espinós, Ana I. Borrás, Francisco J. Aparicio, Carmen López, Agustín R. González-Elipe

PVSkite es un proyecto multidisciplinar que tiene como principales objetivos incorporar las técnicas de plasma de deposición y de procesado de materiales y un conjunto de técnicas sintéticas de vacío al desarrollo de materiales, nanoestructuras y dispositivos basados en perovskitas de haluro. En el caso de las técnicas de plasma, buscamos explorar aproximaciones, como la técnica RPAVD (deposición en vacío asistida por plasmas remotos), a desarrollo de sistemas optimizados de encapsulación de celdas, pasivación de electrodos, ingeniería de intercaras, y diseño de nuevas formulaciones de electrodos para celdas de perovskita de haluro. Esta aproximación queda avalada por algunos resultados recientes y muy prometedores del grupo, sobre la encapsulación de celdas de perovskita y la pasivación de electrodos inorgánicos con películas poliméricas conformales ultradelgadas mediante procesos de plasma. En el caso de los procesos de vacío, el proyecto se centrará en la aplicación de la técnica de deposición en ángulo rasante (GLAD) al diseño de perovskitas cristalinas anisotrópicas para el control de la polarización de la luz, así como en la estructuración de electrodos de transporte de carga. También aquí se parte de algunos resultados iniciales muy recientes que muestran el enorme potencial de esta aproximación en al campo de la síntesis de nanoestructuras de perovskitas de haluro anisotrópicas. Las aproximaciones experimentales propuestas no han sido abordadas en la literatura actual, pero creemos que pueden tener un impacto muy importante en desarrollo de estos materiales y dispositivos. En ambos casos, el grupo cuenta con más de dos décadas de experiencia internacional reconocida en la fabricación de materiales funcionales por estas técnicas y en su aplicación final en dispositivos (fotónicos, sensores, captadores de energía, etc.).

El proyecto abarca actividades fundamentales y aplicadas a diferentes niveles, como la simulación de procesos de crecimiento, la síntesis de nuevos materiales bajo diseño, la caracterización avanzada de propiedades y la interrogación de dispositivos. El desarrollo de una serie de prototipos a escala de laboratorio es un aspecto fundamental de la propuesta, que servirá para validar la viabilidad de los materiales desarrollados. Con este fin se diseñarán las plataformas y los protocolos de medida adecuados. El primer tipo de dispositivo a desarrollar serán celdas de perovskitas estables frente al agua y la humedad que incorporen todas las modificaciones de intercaras, nuevos electrodos y elementos de encapsulación desarrollados en el proyecto. El segundo tipo de dispositivos serán dispositivos optoelectrónicos de perovskita sensibles a la polarización. Se estudiarán dos tipos a) dispositivos emisores de luz polarizada y b) detectores de luz polarizada. El proyecto se completa con una evaluación preliminar de la estabilidad a vacío y en presencia de fuentes de ionización de dispositivos seleccionados.

Además, se cuenta con la colaboración y el interés expreso de cuatro empresas directamente relacionadas con la propuesta: Arquimea, a través de su división de energía, Lasing SA con una amplia experiencia en el uso y desarrollo de elementos y dispositivos fotónicos y Fluxim, líder mundial en el estudio y el desarrollo de equipamiento para el estudio de la estabilidad ambiental de celdas solares. La cuarta, ALTER Tech, está interesada en la potencial aplicación de celdas estables de perovskita en el espacio.


Desarrollo de plasmas intermitentes operados con electricidad renovable para la eliminación y revalorización de CO2


01-12-2022 / 30-11-2024



Investigador Principal: Ana María Gómez Ramírez / Manuel Oliva Ramírez
Organismo Financiador: Ministerio de Ciencia e Innovación "Transición Ecológica y Transición Digital"
Código: TED2021-130124A-I00

Equipo de Investigación: Rafael Álvarez Molina, José Cotrino Bautista, María del Carmen García Martínez (US), Alberto Palmero Acebedo, Agustín R. González-Elipe

La emisión de CO2 representa actualmente un 77% de las emisiones totales de gases de efecto invernadero con origen antropogénico, propiciando un aumento paulatino del calentamiento global del planeta con las consecuentes y nefastas repercusiones medioambientales que ello supone. Por tanto, es indudable la necesidad de propiciar una transición hacia una economía donde el uso intensivo de combustibles fósiles no sea el eje prioritario, favoreciendo el desarrollo de procedimientos de transformación y aprovechamiento químicos respetuosos con el medio ambiente mediante el uso de fuentes energéticas alternativas. El proyecto “Desarrollo de plasmas intermitentes operados con electricidad renovable para la eliminación y revalorización de CO2”, RENOVACO2, pretende el desarrollo de tecnologías de plasma atmosférico que usan la electricidad como vector energético directo para llevar a cabo procesos químicos convencionalmente abordados mediante técnicas catalíticas, que involucran altas presiones y temperaturas y usan catalizadores térmicos con elementos contaminantes y de difícil reciclado. 


Nanogeneradores triboeléctricos para la recolección de energía renovable de gotas de lluvia


01-12-2022 / 30-09-2025



Investigador Principal: Ana Isabel Borrás Martos / María del Carmen López Santos
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: TED2021-130916B-I00

Equipo de Investigación: Gildas Leger, José Cotrino, Ricardo Molina, Juan Ramón Sánchez, Victor Rico, Germán de la Fuente, Juan Pedro Espinós, Antonio José Ginés, Angel Barranco, Luis Alberto Angurel, Jorge Gil, Agustín R. González-Elipe

DropEner tiene como objetivo el desarrollo de paneles de lluvia, es decir, recolectores de energía proveniente de gotas que, basados en el principio del nanogenerador triboeléctrico (TENG), funcionan en condiciones exteriores y pueden fabricarse a través de tecnologías escalables y de alto rendimiento. El proyecto demostrará la aplicación de un concepto innovador patentado recientemente por el grupo Nanotecnología en Superficies y Plasma (CSIC-US), “Tixel”, sobre la recolección de energía cinética proveniente de gotas de líquido en contacto instantáneo con una superficie triboeléctrica integrada en una arquitectura de tipo condensador. Por lo tanto, el principal objetivo es desarrollar un panel de recolección de energía basado en el primer TENG de arquitecturas nano y microestructuradas capaces de generar alta densidad de potencia mediante la implementación de matrices de nanogeneradores triboeléctricos en la microescala, donde cada generador produzca cientos de microvatios de potencia cuando una gota de lluvia con alta velocidad y alta energía golpee su superficie. La potencia de salida total sería equivalente a la suma de la potencia producida por los generadores individuales y podría alcanzar potencialmente cientos de vatios por metro cuadrado cuando se fabrique una matriz de alta densidad bien diseñada. Además, en un paso más allá en el estado del arte para la explotación de captadores de energía de contacto entre sólido-líquido, DropEner persigue el desarrollo de Tixels duraderos y transparentes totalmente compatibles con celdas solares, incluidas las tecnologías de Silicio y de Tercera Generación (como celdas solares de colorantes y celdas solares de perovskita). Los avances esperados abarcan aspectos como el desarrollo de superficies con super-mojabilidad, la explotación de rutas de producción escalables y procesado de materiales, la fabricación de recolectores de energía de gotas transparentes, la prueba de concepto de diseños novedosos de nanogeneradores triboeléctricos y la gestión de energía en sistemas multifuente de recolección de energía intermitente. 


Peliculas delgadas nanoestructuradas crecidas por pulverización catódica con plasmas de helio y otros gases ligeros


01-09-2022 / 31-08-2026



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: PID2021-124439NB-I00

Equipo de Investigación: María del Carmen Jiménez de Haro

La pulverización catódica (magnetron sputtering-MS) es una metodología de deposición física desde fase vapor (PVD) muy usada para la fabricación de películas delgadas y recubrimientos. En la técnica MS se emplean comúnmente mezclas de Ar ó Ar/N2-O2 (MS reactivo) como gas de proceso que se ionizará en una descarga para crear el plasma adecuado y pulverizar el material del blanco. El grupo NanoMatMicro ha sido pionero en la introducción de plasmas de helio en la tecnología de pulverización catódica. Aunque la tasa de deposición puede bajar, demostramos la formación en condiciones controladas de nanoporosidad y/o gas atrapado (nanoburbujas de He y N2) en las películas producidas. En particular las láminas sólidas que contienen nanoporos llenos de gas tienen características únicas: permiten atrapar una gran cantidad de gas en un estado condensado con alta estabilidad y proporcionan una ruta para modificar las propiedades del material preparado. La técnica MS es fácil de escalar y mucho más barata que las tecnologías alternativas basadas en la implantación de iones de alta energía. Sobre esta base, proponemos seguir desarrollando una metodología bottom-up innovadora y versátil para fabricar películas delgadas (Si, C, otros metaloides y metales) que promueva la porosidad abierta o, por el contrario, permita estabilizar las "nanoburbujas" atrapadas del gas de proceso (He , Ne, N2, H2 y sus isótopos).

La metodología se investigará principalmente para fabricar blancos sólidos y estándares del gas atrapado para estudios de reacciones nucleares. Nuestro trabajo permitirá que los gases ligeros y sus isótopos estén disponibles en un estado condensado y en un formato fácil de manejar sin necesidad de celdas de alta presión o dispositivos criogénicos. Junto con una red de investigadores colaboradores de las áreas de Física Nuclear y Astrofísica, nuestro objetivo es llevar esta aplicación desde la prueba de concepto hasta los experimentos finales en grandes instalaciones. También cabe mencionar que el control del proceso desde estructuras con gas atrapado a nanoporosas permitirá estudiar aplicaciones adicionales en el proyecto como dispositivos ópticos, emisores de luz UV o recubrimientos catalíticos. El proyecto incluye el diseño y control de proceso en nuestras cámaras de MS para trabajar con los diferentes gases ligeros aquí propuestos. Se seguirán implementando metodologías de bajo consumo para isótopos escasos (por ejemplo, 3He). El objetivo final es implementar una configuración mejorada de MS y desarrollar la metodología bottom-up propuesta en términos de combinaciones de matriz y gas, mezclas de gases, variedad de soportes y diseños autosoportados o multicapa que permitan las aplicaciones innovadoras.

Una tarea importante es también determinar el mecanismo de crecimiento de las láminas. La caracterización del plasma durante el proceso de deposición y el uso de la herramienta de simulación SRIM pueden contribuir en gran medida a una mejor comprensión y control de los procesos de crecimiento. Para comprender la microestructura, composición y propiedades físico-químicas de los nuevos materiales, se llevará a cabo una caracterización química y microestructural en la nanoescala con una variedad de técnicas. Destacan las microscopías electrónicas (TEM y SEM) que incluyen la espectroscopia de pérdida de energía de electrones y las técnicas de análisis por haz de iones para la determinación de la composición elemental en profundidad.


Nueva generación de nanorecubrimientos dieléctricos conformales para dispositivos electrónicos emergentes por tecnología de plasma (PlasmaDielec)


01-01-2022 / 31-05-2023



Investigador Principal: Francisco Javier Aparicio Rebollo
Organismo Financiador: Junta de Andalucía
Código: US-1381057

Equipo de Investigación: Ana Isabel Borras Martos, Ramon Escobar Galindo, Lidia Contreras Bernal

Los avances recientes en nanomateriales y técnicas de procesado están conduciendo al desarrollo de nanodispositivos de elevada miniaturización y nuevas funcionalidades en el campo de los dispositivos electrónicos flexibles. El proyecto aborda el desarrollo de nueva generación de materiales dieléctricos en forma de láminas delgadas de espesor nanométrico mediante tecnología de plasma teniendo como meta final la fabricación de transistores orgánicos flexibles de elevadas prestaciones. La metodología de deposición por plasma propuesta es una técnica pionera desarrollada en nuestro laboratorio que permite regular de manera controlada las propiedades dieléctricas y la interacción con líquidos de estos recubrimientos, así como su deposición conformal sobre nanoestructuras de elevada relación de aspecto como son nanohilos y nanotubos de uso en electrónica molecular. La técnica de plasma propuesta es completamente compatible con los procesos actualmente empleados a nivel industrial en la fabricación de microdispositivos y nanocomponentes electrónicos. Estas ventajas y los resultados previos de la técnica de plasma propuesta en el desarrollo de materiales fotónicos y sensores avalan la viabilidad del proyecto. Como resultados PlasmaDielec se establecerá las bases para el desarrollo de nuevos procedimientos y una nueva generación de materiales dieléctricos de para el futuro desarrollo de la electrónica flexible.


Nanoscopías y Espectroscopías integradas para el análisis en la nano-escala de nuevos materiales funcionales


05-10-2021 / 30-06-2023



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Junta de Andalucía
Código: P20_00239 - PAIDI 2020

Equipo de Investigación: M. Carmen Jiménez de Haro

El desarrollo de los nanomateriales y materiales funcionales, así como sus aplicaciones nanotecnológicas, vienen determinados por las capacidades actuales para la caracterización de la microestructura, la composición y las propiedades de los materiales en la nano-escala. El proyecto propone potenciar una investigación de frontera en la caracterización microestructural de materiales. Se integrarán las técnicas nanoscópicas y espectroscópicas, ligadas a la microscopía electrónica (sonda de electrones), con las técnicas asociadas a las sondas de fotones (rayos-X) y de haces de iones (técnicas IBA en general). La caracterización se asociará a materiales funcionales seleccionados de alto interés actual en la temática de recubrimientos y láminas delgadas en las que el equipo de trabajo es experto.

Será objetivo central el desarrollo y aplicación de manera integrada de las técnicas disponibles con múltiples sondas, tanto en el ICMS, como en otros centros de las Universidades de Sevilla (CITIUS, CNA) y Cádiz (servicios centrales). Igualmente a través de colaboraciones y solicitudes de medidas se tendrá acceso a otras instalaciones internacionales.

En el proyecto se dispondrá de materiales seleccionados en dos tecnologías emergentes: i) Láminas delgadas y recubrimientos nanoporosos que estabilizan gases a ultra-alta densidad y presión. ii) Catalizadores para los procesos de almacenamiento y generación de hidrógeno en líquidos orgánicos portadores de hidrógeno (LOHCs). La caracterización avanzada que se propone contribuirá a la comprensión fundamental de las relaciones síntesis-microestructura-propiedades con el objetivo de alcanzar un diseño racional de nuevos materiales funcionales en las líneas seleccionadas. El proyecto incide directamente en las tecnologías facilitadoras o emergentes como son “la nanotecnología” y “los materiales avanzados”. Incide también en los retos sociales y objetivos RIS3 de Andalucía en relación al almacenamiento de energías renovables.


Dispositivo optofluidico NIR para análisis de líquidos


01-12-2021 / 30-11-2023



Investigador Principal: Francisco Yubero Valencia
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: PDC2021-121379-I00 - Proyectos I+D+i "Prueba de Concepto"

Equipo de Investigación: Juan Pedro Espinós Manzorro, Ramón González García, Victor J. Rico Gavira, Agustín R. González-Elipe

NIRFLOW es un proyecto I+D+i para la realización de una Prueba de Concepto en el que se plantea desarrollar un prototipo precomercial para análisis óptico en el infrarojo cercano de fluidos en condiciones de flujo en entornos industriales relevantes. El proyecto se basa en varias innovaciones no contempladas en equipos comerciales basados en análisis NIR hoy en el mercado. De un lado, sustituir la óptica de análisis NIR convencional operada por espectrómetros NIR basados en redes de difracción o óptica de Fourier por una selección de la longitud de onda de análisis basada en combinaciones de filtros ópticos de paso alto y paso bajo variables de forma continua con respuesta sintonizada (centro y anchura de banda) a voluntad en el NIR. De otro lado, la celda optofluidica a desarrollar, operada en modo transflectancia, se caracteriza por tener camino óptico de análisis variable y sintonizable a los sobretonos de las absorciones características de las moléculas presentes en el fluido problema. De esta manera, los análisis estadísticos característicos de la espectroscopía NIR se van a ver apoyados por variables independiente (medidas correspondientes no sólo a variaciones de longitud de onda, sino también a distintos caminos ópticos de análisis), lo cual va a propiciar análisis estadísticos más robustos que los convencionales. Finalmente, el equipo se va a desarrollar con una concepción microfluídica de análisis automática, para su operación en remoto mediante tecnología wireless. Estas tres innovaciones hacen de NIRFLOW un proyecto I+D+i en el que parte de los conocimientos y uno de los desarrollos realizado en un proyecto de investigación previo del Plan Estatal (MAT2016-79866-R), parcialmente protegido con una patente, se pretende transferir a la sociedad a través del desarrollo de un equipo precomercial que demuestre sus capacidades de análisis en entornos operacionales significativos, en particular para el seguimiento de procesos de fermentación ligados a la producción de vinos.


Nanorecubrimientos dieléctricos para dispositivos electrónicos Flexibles por tecnología de plasma (FLEXDIELEC)


01-09-2021 / 30-08-2025



Investigador Principal: Francisco Javier Aparicio Rebollo
Organismo Financiador: Junta de Andalucía "Programa Emergia"
Código: EMERGIA20_00346


Dadas sus características físicas y mecánicas de la tecnología de dispositivos electrónicos flexibles emergente combina estructuras multicapas de láminas delgadas flexibles, nanomateriales 2D, o nanoconductores 1D, como son los nanotubos de carbono y los nanohilos. Sin embargo, estos presentan diferentes limitaciones relacionadas con su degradación frente a agentes ambientales e incompatibilidad con las técnicas de fabricación convencionales más presentes a nivel industrial. El proyecto FlexDielec persigue el desarrollo de una nueva generación de materiales dieléctricos para el desarrollo de dispositivos electrónicos flexibles avanzados, superando estas limitaciones. Con este fin, se empleará una técnica pionera de plasma remotos, desarrollada por el IP, que regula en un amplio rango la composición y propiedades de nanocomposites orgánicos funcionales. Esta es una metodología de vía seca (ausencia de disolventes) y a temperatura ambiente, lo que asegura su completa compatibilidad con el uso de sustratos sensibles, como muchos de los que tienen mayores perspectivas de implementación en campo de la electrónica flexible (materiales poliméricos, tejidos, papel, nanomateriales 2D, nanofibras orgánicas…).


Plasmas atmosféricos de arco deslizante para procesos sostenibles


01-09-2021 / 31-08-2024



Investigador Principal: Ana María Gómez Ramírez
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: PID2020-114270RA-I00 - Proyectos I+D+i "Retos Investigación"

Equipo de Investigación: José Javier Brey Sánchez (Universidad Loyola), José Cotrino Bautista, Paula de Navascués Garvín, Manuel Oliva Ramírez, Antonio Rodero Serrano (Universidad de Córdoba)

La necesidad de propiciar una transición efectiva desde una economía basada en el uso intensivo de combustibles fósiles a otra donde los criterios de desarrollo se basen en procesos sostenibles que no impliquen la generación de CO2 hace necesaria la puesta a punto de nuevos procesos, donde la fuente de energía primaria sea la electricidad generada a partir de fuentes renovables. El proyecto “Plasmas Atmosféricos de Arco Deslizante para Procesos Sostenibles”, FIREBOW en adelante, pretende el desarrollo de tecnologías de plasma atmosférico que usan la electricidad como vector energético directo para llevar a cabo procesos químicos convencionalmente abordados mediante técnicas catalíticas (a altas presiones y temperaturas, con bajos rendimientos y obtención de subproductos no deseados). En concreto se persigue la puesta a punto de un reactor de Plasma Atmosférico de Arco Deslizante (PAAD) para inducir tres procesos de gran impacto industrial y medioambiental, como son la síntesis de amoniaco (NH3), la producción de hidrógeno (H2) y la descontaminación de agua. El amoniaco es la sustancia base de los fertilizantes usados en agricultura, y su demanda aumenta conforme las necesidades de alimentación mundiales. En cuanto al hidrógeno, es conocido que el camino hacia una economía basada en dicho combustible es uno de los retos del siglo XXI. Por otro lado, el desarrollo de técnicas novedosas para la depuración de aguas es cada vez más necesaria, debido al aumento de contaminante emergentes, sustancias tales como pesticidas, compuestos derivados de la industria farmacéutica y química, microorganismos e incluso productos de higiene personal que los métodos convencionales no son capaces de eliminar en su totalidad. FIREBOW propone, en una primera etapa, desarrollar la tecnología PAAD mediante el diseño, construcción, modelización y puesta a punto de un reactor de arco deslizante. Se explorarán posibles modificaciones sobre los modelos de reactores PAAD actuales, contemplándose el efecto de la incorporación de materiales piezoeléctricos para inducir fenómenos de emisión secundaria de electrones, la modificación de las características superficiales de los electrodos o la geometría del sistema a fin de propiciar en el futuro una mejora en el rendimiento de los procesos estudiados. La complejidad de los procesos básicos involucrados en este tipo de reactores implicará un estudio fundamental de su respuesta eléctrica y de los fenómenos de transporte de masa y carga, así como una caracterización exhaustiva y diagnosis del plasma en función de parámetros como flujo de gases, interacción entre especies excitadas, tiempo de residencia y otros parámetros básicos de operación. Tanto la caracterización experimental como la simulación teórica del reactor, esta última llevada a cabo mediante métodos computacionales, serán fundamentales para su correcto funcionamiento y optimización de los procesos propuestos. En una segunda etapa se abordará el estudio de las reacciones de obtención de H2 y NH3, con el objetivo de maximizar el rendimiento energético de dichos procesos, así como de la purificación de agua. El desarrollo científico-tecnológico propuesto en FIREBOW es de gran interés para diferentes actores socio-económicos, planteándose actividades de transferencia a las empresas y entidades que ya han mostrado su interés en el desarrollo de mismo.


Procesos de Nucleación y Crecimiento en Superficies Piezoeléctricas Excitadas Acústicamente en Atmósferas de Plasma/Vacío


01-09-2021 / 31-08-2024



Investigador Principal: Alberto Palmero Acebedo
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: PID2020-112620GB-I00 - Proyectos I+D+i "Generación de Conocimiento"

Equipo de Investigación: Rafael Alvarez Molina, Victor J. Rico Gavira, Agustín R. González-Elipe

Este proyecto aborda el estudio de los fenómenos de nucleación atómica y crecimiento de películas delgadas sobre materiales piezoeléctricos sometidos a excitación acústica en atmósferas de plasma y vacío. Los materiales piezoeléctricos se caracterizan por la aparición de una polarización eléctrica no nula al someterlos a una deformación mecánica, y por el efecto contrario, la aparición de una deformación mecánica al someterlos a una excitación eléctrica y, en la actualidad, se emplean en multitud de aplicaciones y dispositivos, tales como sensores de lluvia, pantallas táctiles o manipulación de líquidos en la microescala, entre otros. En un trabajo seminal publicado por el grupo investigador se demostró que, al crecer una película delgada mediante técnicas de plasma sobre este tipo de superficies excitadas, ésta se estructuraba de acuerdo al patrón definido por las ondas. Este resultado inicial demostraba que la interacción entre la onda/película delgada en crecimiento podría utilizarse como nueva metodología de nanoestructuración de superficies. En este proyecto se aborda esta problemática de tipo fundamental, estudiando específicamente dos mecanismos principales de interacción: i) la transferencia directa de energía/momento de la onda acústica a las especies depositadas, y ii) la interacción entre la onda de polarización eléctrica que se propaga por el material piezoeléctrico y las líneas de campo eléctrico en el plasma, con incidencia directa en el transporte de especies cargadas y al bombardeo superficial selectivo del piezoeléctrico durante el crecimiento de la película. De esta manera, este proyecto se centra en la descripción, desarrollo y compresión de una nueva fenomenología, y en el desarrollo de todo el marco teórico y conceptual que permita entender dicha interacción. Se espera que la activación acústica de piezoeléctricos y su efecto en atmósferas de plasma se convierta en un nuevo procedimiento para inducir la formación de centros de nucleación para la micro- y nano-estructuración de películas delgadas, permitiendo nuevos desarrollos en el campo de la física de superficies. Asimismo, en el campo de la física del plasma, la posibilidad de modular la interacción entre el plasma y una superficie de acuerdo a un patrón definido por ondas electro-acústicas podría abrir procedimientos alternativos para operar dispositivos de microplasmas o pantallas de plasma.


Funcionalización superficial y modelos de difusión de factores de germinación en semillas tratadas con plasmas | PLASMASEED


01-01-2021 / 31-12-2022



Investigador Principal: María del Carmen López Santos / Antonio Prados Montaño (US)
Organismo Financiador: Junta de Andalucía
Código: US-1381045

Equipo de Investigación: Agustín Rodríguez González-Elipe, Francisco Yubero Valencia

PLASMASEED aborda la inclusión de la tecnología de vacío y plasma para la funcionalización superficial de semillas como una estrategia eficaz y limpia para que los cultivos sean menos dependientes de los cambios del entorno. Se pretenden analizar los factores y mecanismos básicos que inciden en la mejora de la germinación tratando las semillas desde una aproximación multidisciplinar que combina conceptos básicos de biofísica, caracterización avanzada y procesado por vacío y plasma. El efecto de campos eléctricos asociados a los plasmas y las características físico-químicas de estos, la influencia de la difusión de otros factores de germinación además del agua (oxígeno, luz, etc.), la difusión de nutrientes como especies nitratos u otras de interés para la germinación, etc., son factores experimentales que se modelizan usando procedimientos de Monte Carlo y mecánica estadística para proponer modelos holísticos de difusión de factores de germinación a través de las membranas de semillas y de la influencia de los tratamientos superficiales con técnicas de plasma para modificar y / o controlar tales procesos.


Plasmas atmosféricos de arco deslizante para la producción sostenible de amoniaco e hidrógeno (ARCPLAS)


01-01-2021 / 31-12-2022



Investigador Principal: Ana María Gómez Ramírez / José Cotrino Bautista
Organismo Financiador: Junta de Andalucía
Código: US-1380977

Equipo de Investigación: Rafael Alvarez Molina, José Javier Brey Sánchez (Universidad Loyola), Jesús Cuevas Maraver (US), Alberto Palmero Acebedo, Juan F. Rodríguez Archilla (US)

El proyecto “Plasmas atmosféricos de arco deslizante para la producción sostenible de amoniaco e hidrógeno”, ARCPLAS en adelante, pretende el desarrollo de procesos de transformación química de gases mediante tecnologías de plasma atmosférico que usan la electricidad como vector energético directo. En concreto se persigue la puesta a punto de un reactor de Plasmas Atmosféricos de Arco Deslizante (PAAD) para inducir dos procesos de gran impacto industrial y medioambiental, como son la síntesis de amoniaco (NH3) y la producción de hidrógeno (H2). El amoniaco es la sustancia base de los fertilizantes usados en agricultura, y su demanda aumenta conforme las necesidades de alimentación mundiales. En cuanto al hidrógeno, de sobra es conocido que el camino hacia una economía basada en dicho combustible es uno de los retos del siglo XXI. ARCPLAS propone, en una primera etapa, desarrollar la tecnología PAAD mediante el diseño, construcción, modelización y puesta a punto de un reactor de arco deslizante. La complejidad de los procesos básicos implicados en este tipo de reactores implicará un estudio fundamental de su respuesta eléctrica y de los fenómenos de transporte de masa y carga, así como una caracterización exhaustiva y diagnosis del plasma en función de parámetros como flujo de gases, interacción entre especies excitadas, tiempo de residencia, características químicas de los gases implicados y otros parámetros básicos de operación. Tanto la caracterización experimental como teórica del reactor, esta última llevada a cabo mediante métodos computacionales, serán fundamentales para su correcto funcionamiento y optimización de los procesos propuestos. En una segunda etapa se abordará el estudio de las reacciones de obtención de H2 y NH3, con el objetivo de maximizar su rendimiento químico, así como el rendimiento energético del reactor. Finalmente, en una última etapa del proyecto, se explorarán posibles modificaciones sobre el modelo de reactor PAAD desarrollado, contemplándose el efecto de la incorporación de materiales piezoeléctricos para inducir fenómenos de emisión secundaria de electrones, la modificación de las características superficiales de los electrodos o la geometría del sistema a fin de propiciar en el futuro una mejora en el rendimiento de los procesos estudiados.


Estructuras adaptativas multiresponsivas para fotónica integrada, piezo/tribotronica y monitorización optofluídica | AdFunc


01-06-2020 / 31-05-2023



Investigador Principal: Angel Barranco Quero / Ana Isabel Borrás Martos
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: PID2019-110430GB-C21 - Proyectos I+D+i "Generación de Conocimiento"

Equipo de Investigación: José Cotrino Bautista, Victor J. Rico Gavira, Francisco Yubero Valencia, Juan Pedro Espinós Manzorro, Agustín R. González-Elipe

AdFUNC es un proyecto muy interdisciplinar que tiene como principal objetivo conseguir un progreso significativo en dos temáticas en la frontera de la Ciencia de Materiales: el desarrollo de sensores con capacidad multirespuesta y de sistemas de energía activados por luz. Los denominadores comunes de AdFUNC son el diseño inteligente de arquitecturas complejas en la nanoescala y el desarrollo de demostradores a escala de laboratorio.

Estamos convencidos de que el proyecto nos abre una ventana de oportunidad para realizar investigaciones que podemos clasificar en cuatro áreas: i) Aplicaciones y dispositivos: Desarrollaremos los recientemente descubiertos efectos tribotrónicos y piezotrónicos para fabricar dispositivos sensores autoalimentados. Con estos materiales, en combinación con varias tecnologías avanzadas de sensado fotónico y espectro-electroquímico, expandiremos la eficiencia, multiactuación y multirespuesta de sistemas adaptativos optofluídicos. Estos sistemas, manteniendo una arquitectura común, presentarán una respuesta diferenciada frente a escenarios reales diversos y complejos, que se simularán en el proyecto (alteraciones medioambientales como vertidos, accidentes, amenazas químicas o de explosivos). También se plantean dispositivos captadores de energía solar en condiciones de baja iluminación, captadores de energía mecánica y dispositivos que sean capaces de acoplar luz y movimiento a la activación de procesos de descomposición electroquímica del agua. Ii) Nanomateriales: Adfunc es un proyecto donde concurren un equipo de especialistas en el desarrollo de nanoestructuras soportadas por distintas tecnologías. Esto nos permitirá, por primera vez, implementar un conjunto de nanoarquitecturas 3D (nanohilos, nanotubos, core@shell) y el diseño de materiales con estructuras nanoporosas controladas (capas esculturales, nanocanales, porosidad asociada en varias escalas, multicapas ópticas porosas, desarrollos pioneros de redes metaloorgánicas (MOFs) en estructuras fotónicas porosas) directamente a la mejora de los componentes activos de los dispositivos del proyecto. Iii) Estrategia. El proyecto nos da la oportunidad de trabajar simultáneamente en rutas sintéticas nuevas, caracterización avanzada de materiales y propiedades, integración de materiales en dispositivos, y esto a la vez que se tiene información de modelado y simulación. Iv) Perspectiva de escalabilidad: En todos los casos se utilizarán métodos y técnicas compatibles con procesos industriales establecidos, como el plasma y el vacío típicos de la industria optoelectrónica y microelectrónica, y procesos de síntesis en disolución. Otro aspecto interesante, es la posibilidad de introducir plásticos y polímeros para fabricar dispositivos, lo que puede permitir revalorizar residuos de la industria del plástico, en un esfuerzo de economía circular en el que investigadores del proyecto están comprometidos.

AdFunc sólo es posible gracias al esfuerzo conjunto de un gran número de investigadores, en su mayoría del ICMS-CSIC y la Universidad Pablo de Olavide, que se completa con un grupo de investigadores de otros centros y colaboradores internacionales con experiencia e interés complementarios. Es precisamente la coordinación de un número tan elevado de especialistas (25 doctores en los dos subproyectos) lo que nos permite plantear el desarrollo de un conjunto de actividades tan completo y ambicioso.  


Recubrimientos innovadores preparados por Magnetron Sputtering para absorción solar selectiva


01-06-2020 / 31-12-2024



Investigador Principal: Juan Carlos Sánchez López / Ramón Escobar Galindo (Abengoa Solar New Tecnologies, S.A.)
Organismo Financiador: Ministerio de Ciencia, Innovación y Universidades
Código: PID2019-104256RB-I00 "Retos Investigación"

Equipo de Investigación: Cristina Rojas Ruiz, Belinda Sigüenza Carballo

El cambio climático ocasionado por las emisiones de gases con efecto invernadero y el agotamiento de los combustibles fósiles a corto-medio plazo hacen necesaria la búsqueda de nuevas fuentes de energía alternativas, limpias y renovables. De entre ellas, la energía solar es una de las mejores opciones por su gran disponibilidad para la generación de calor y electricidad.

El objetivo de este proyecto va encaminado al desarrollo de nuevos recubrimientos absorbedores solares selectivos crecidos en forma de multicapas basados en nitruros metálicos de cromo y aluminio (CrAlN). Las propiedades de resistencia a la oxidación y estabilidad térmica del CrAlN unidas a un diseño nanoestructurado adecuado permitirán mantener unas buenas prestaciones ópticas (alta absorbancia y baja emitancia) y mejorar su durabilidad a alta temperatura. El incremento de la temperatura de trabajo (T>550ºC) conllevará una mejora de la eficiencia y una reducción de costes de las plantas de concentración de solar térmica, haciéndolas más competitivas. Para su preparación se utilizará la técnica de pulverización catódica mediante impulsos de alta intensidad (HiPIMS), una variante reciente de la pulverización catódica convencional que permite mejorar la densidad y compacidad de las capas gracias a un mayor grado de ionización del plasma. Estas propiedades son de interés para mejorar la adhesión al sustrato y ralentizar los procesos de degradación térmica. Además de los nitruros se ensayarían otras configuraciones cambiando el tipo de material absorbedor (oxinitruros y nanocomposites de carburos metálicos).

El proyecto comprenderá todas las etapas, desde la síntesis de los materiales componentes de las estructuras solares selectivas, diseño y simulación de su comportamiento óptico, a su validación en condiciones similares a la aplicación final (a nivel de laboratorio y ensayos de campo). La caracterización estructural, química y de estabilidad térmica y resistencia a la oxidación discurrirá en paralelo con el fin de optimizar los recubrimientos solares selectivos con mejores prestaciones y durabilidad.


Tecnología de plasma para la fabricación de celdas solares de perovskita eficientes y duraderas a prueba de agua


01-06-2020 / 31-05-2023



Investigador Principal: Juan Ramón Sánchez Valencia / Maria del Carmen López Santos
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: PID2019-109603RA-I00 "Retos"

Equipo de Investigación: Juan Pedro Espinós Manzorro, Xabier García Casas, Víctor López Flores, Javier Castillo Seoane

Las celdas solares –dispositivos que transforman directamente la luz solar en electricidad- son de vital interés para el futuro sostenible del planeta. Durante los últimos años y conscientes de este hecho, la comunidad científica ha realizado un gran esfuerzo por mejorar la eficiencia de estos dispositivos. Un ejemplo particular de celda solar que contiene una perovskita de haluro organometálico como absorbedor de luz han centrado la atención de la comunidad científica durante la última década debido, sobre todo, a su alta eficiencia y bajo coste. Esta tecnología de celda solar supone una alternativa prometedora a las celdas actuales (basadas en Si y en calcogenuros), aunque se enfrentan a un reto científico y tecnológico que no ha sido resuelto en 10 años desde su descubrimiento: para que la realización final y comercial de las celdas de perovskita sea posible, necesitan alcanzar una mayor estabilidad, durabilidad y reproducibilidad. El principal problema radica en la alta sensibilidad que presentan estas perovskitas al oxígeno y humedad ambiental, que producen una rápida degradación del comportamiento de la celda en un tiempo extremadamente corto, haciendo inviable su comercialización.

DuraSol persigue abordar este gran reto científico y tecnológico mediante la fabricación de componentes de la celda mediante tecnología de vacío y plasma. Estas metodologías son escalables industrialmente y presentan grandes ventajas con respecto a las metodologías en disolución (las más usadas), entre las que destacan: su alta versatilidad, control de composición y microestructura, bajo coste, que son respetuosas con el medio ambiente ya que no precisan disolventes, no producen emisiones contaminantes y son compatibles con la tecnología actual de semiconductores.

El objetivo principal de DuraSol es la fabricación de celdas solares de perovskita “a prueba de agua” mediante integración de componentes fabricados por metodologías de vacío y plasma en forma de películas delgadas y nanoestructuras, que actúan como sellantes hidrofóbicos. La viabilidad de DuraSol se basa en resultados recientes que demuestran que la fabricación asistida por plasma de distintos componentes de la celda solar puede ser una de las vías más prometedoras para aumentar su estabilidad y durabilidad, que es hoy en día el cuello de botella que impide su comercialización. Cabe señalar que no hay ningún ejemplo en la literatura de este enfoque sintético, y se espera que esta oportunidad demuestre las ventajas y la versatilidad de esta metodología innovadora en un campo de muy alto impacto. La investigación propuesta en DuraSol se enmarca dentro de las áreas prioritarias del programa Horizon 2021-2027 de la Unión Europea y responden a varios de los retos propuestos en la presente convocatoria de “Energía segura, eficiente y limpia” (Reto 3) y de “Cambio climático y utilización de recursos y materias primas” (Reto 5).


Tecnología de plasma para el desarrollo de una nueva generación de conductores de huecos en celdas solares de perovskita. PlasmaCells


01-01-2020 / 31-12-2022



Investigador Principal: Juan Ramón Sánchez Valencia (US)
Organismo Financiador: Junta de Andalucía
Código: US-1263142 "Emergente"

Equipo de Investigación: Angel Barranco Quero, Juan Pedro Espinós Manzorro, Cristina Rojas Ruiz, José Cotrino Bautista

Las celdas solares (CSs) de tercera generación son dispositivos nanotecnológicos que convierten directamente la luz solar en electricidad y suponen el paradigma de la investigación en energías renovables de cuyo aprovechamiento dependerá el futuro energético del planeta. Recientemente, un ejemplo particular de CSs que contienen una perovskita de haluro organometálico como absorbedor de luz han centrado la atención de la comunidad científica debido, ante todo, a su alta eficiencia y bajo coste. Estas características las convierten en una alternativa prometedora a las celdas actuales (de Si y calcogenuros). Sin embargo, para que la realización final y comercial de las celdas de perovskita sea posible es necesario que alcancen una mayor estabilidad, durabilidad y reproducibilidad. Los avances más importantes alcanzados se han debido a la intensa investigación sobre los elementos que integran esta CS: conductor de electrones, perovskita y conductor de huecos. En concreto, este último elemento ha tenido una importancia crucial en su evolución tras la implementación de los conductores de huecos en estado sólido.

PlasmaCells persigue abordar por primera vez la síntesis de una nueva familia de conductores de huecos por técnicas de vacío y plasma. Estas metodologías son escalables industrialmente y presentan grandes ventajas con respecto a las metodologías en disolución (las más usadas), entre las que destacan: su alta versatilidad, control de composición y microestructura, bajo coste, que son respetuosas con el medio ambiente ya que no precisan disolventes, no producen emisiones contaminantes y son compatibles con la tecnología actual de semiconductores.

El objetivo principal de PlasmaCells es la integración de estos nuevos conductores de huecos procesados por plasma en CSs de perovskita. La importancia del proyecto se basa en resultados recientes obtenidos por el Investigador Principal (IP) que demuestran que la aproximación propuesta puede ser una de las vías más prometedoras para el aumento de la estabilidad, durabilidad y reproducibilidad de estas CSs, que actualmente suponen el cuello de botella que impide su industrialización. Cabe destacar que no existe en la bibliografía ningún ejemplo sobre esta aproximación sintética para el desarrollo de conductores de huecos. Se espera que esta oportunidad permita demostrar las ventajas y versatilidad de esta metodología innovadora en un campo de alto impacto, que se enmarca dentro de las áreas prioritarias RIS3 Andalucía y en el PAIDI 2020 de crecimiento sostenible, eficiencia energética y energías renovables.


Descongelación inteligente y sostenible mediante ingeniería de ondas acústicas aplicadas a superficies | SOUNDOFICE


01-11-2020 / 31-10-2024



Investigador Principal: Coordinador ICMS: Ana Isabel Borrás Martos
Organismo Financiador: European Commission Horizon 2020
Código: H2020-FET-OPEN/0717

Equipo de Investigación: Agustín R. González-Elipe, Juan Pedro Espinós, Francisco Yubero, Ángel Barranco, Víctor Rico, María del Carmen López Santos




Icing on surfaces is commonplace in nature and industry and too often causes catastrophic events. SOUNDofICE ultimate goal is to overcome costly and environmentally harmful de-icing methods with a pioneering strategy based on the surface engineering of MHz Acoustic Waves for a smart and sustainable removal of ice. This technology encompasses the autonomous detection and low-energy-consuming removal of accreted ice on any material and geometry. For the first time, both detection and de-icing will share the same operating principle. The visionary research program covers the modeling of surface wave atom excitation of ice aggregates, integration of acoustic transducers on large areas, and the development of surface engineering solutions to stack micron-size interdigitated electrodes together with different layers providing efficient wave propagation, anti-icing capacity, and aging resistance. We will demonstrate that this de-icing strategy surpasses existing methods in performance, multifunctionality, and capacity of integration on industrially relevant substrates as validated with proof of concept devices suited for the aeronautic and wind power industries. SOUNDofICE high-risks will be confronted by a strongly interdisciplinary team from five academic centers covering both the fundamental and applied aspects. Two SMEs with first-hand experience in icing will be in charge of testing this technology and its future transfer to key EU players in aeronautics, renewable energy, and household appliances. An Advisory Board incorporating relevant companies will contribute to effective dissemination and benchmarking. The flexibility of the R&D plan, multidisciplinarity, and assistance of the AdB guarantee the success of this proposal, bringing up a unique opportunity for young academia leaders and SMEs from five different countries to strengthen the EU position on a high fundamental and technological impact field, just on the moment when the climate issues are of maxima importance.

*Participantes
- INMA: Instituto de Nanociencia y Materiales de Aragón, Spain
-UNIZAR: Universidad de Zaragoza, Spain
-TECPAR: Fundacja Partnerstwa Technologicznego Technology Partners;  Poland
- IFW: Leibniz-Institut Fuer Festkoerper- Und Werkstoffforschung Dresden E.V.;  Germany
-TAU: Tampereen Korkeakoulusaatio SR;  Finland
- INTA: Instituto Nacional De Tecnica Aeroespacial Esteban Terradas; Spain
- Villinger: VILLINGER GMBH,  Austria
- EnerOcean: EnerOcean S.L.,  Spain


Diseño de nanomateriales tridimensionales para la solución todo en uno a la recolección de energía ambiental de fuentes múltiples | 3DSCAVENGERS


01-03-2020 / 28-02-2025



Investigador Principal: Ana Isabel Borrás Martos
Organismo Financiador: Unión Europea
Código: H2020-ERC-STG/0655 STARTING GRANT






https://3dscavengers.icms.us-csic.es/

Thermal and solar energy as well as body movement are all sources of energy. They can be exploited by advanced technology, obviating the need for battery recharging. These local ambient sources of energy can be captured and stored. However, their low intensity and intermittent nature reduces the recovery of energy by microscale instruments, highlighting the need for an integrated multisource energy harvester. Existing methods combine different single source scavengers in one instrument or use multifunctional materials to concurrently convert various energy sources into electricity.

The EU-funded 3DScavengers project proposes a compact solution based on the nanoscale architecture of multifunctional three-dimensional materials to fill the gap between the two existing methods. These nanoarchitectures will be able to simultaneous and individual harvesting from light, movement and temperature fluctuations. 3DScavengers ultimate goal is to apply a scalable and environmental friendly one-reactor plasma and vacuum approach for the synthesis of this advanced generation of nanomaterials.

 

 

@dscavengers


Modelado e implementación de la técnica Freeze-Casting: gradientes de porosidad con un equilibrio tribo-mecánico y comportamiento celular electro-estimulado


01-02-2020 / 31-01-2022



Investigador Principal: Yadir Torres Hernández (US) / Juan Carlos Sánchez López
Organismo Financiador: Junta de Andalucía. Universidad de Sevilla
Código: US-1259771

Equipo de Investigación: Ana María Beltrán Custodio, Alberto Olmo Fernández, Paloma Trueba Muñoz, María de los Ángeles Vázquez Gámez

El titanio comercialmente puro (Ti c.p.) y la aleación Ti6Al4V, son los biomateriales metálicos con el mejor pronóstico para la reparación clínica del tejido óseo. Sin embargo, a pesar de sus ventajas, 5-10% de los implantes fallan durante los cinco años post-implantación. Éstos se asocian fundamentalmente al apantallamiento de tensiones (diferencias de rigidez entre el implante-hueso), el empleo de criterios de diseño (fractura y fatiga) no adecuados para biomateriales, a los fenómenos de tribo-corrosión en condiciones de servicio y a los problemas que ocurren en la intercara (micromovimientos y/o presencia de bacterias) que limitan la capacidad de oseintegración. En este proyecto se propone fabricar e implementar un dispositivo sencillo y económico para obtener cilindros con porosidad controlada (gradiente) y alargada mediante la técnica de congelación dirigida. Se desarrollaran modelos de elementos finitos para estimar el crecimiento geométrico de las dendritas de hielo y el comportamiento mecánico de los cilindros porosos (distribución de esfuerzos y deformaciones), usando radiografías en tiempo real del proceso de congelación dirigida, así como los parámetros que caracterizan la microestructura (proporción, tamaño, morfología de la porosidad) y el comportamiento a compresión (rigidez y límite de fluencia). Además, se plantea la generación de patrones de rugosidad superficial mediante el bombardeo de iones, encaminados a mejorar la unión intima entre el implante y el tejido óseo. Por otra parte, se plantean protocolos in-vitro adecuados para evaluar la citotoxicidad, la adhesión, diferenciación y proliferación celular. Finalmente, se desarrollará un sistema de medida de bio-impedancia que permita racionalizar la influencia de la porosidad, el acabado superficial y los estímulos eléctricos en el comportamiento in-situ de osteoblastos. En este contexto, el objetivo principal es fabricar cilindros con una porosidad controlada y su superficie modificada, que permita garantizar un mejor equilibrio biomecánico, tribo-corrosivo y biofuncional (in-growth y oseointegración del tejido óseo y el implante).


Nuevos recubrimientos nanoestructurados para absorción eficiente de la radiación solar en dispositivos de concentración


01-01-2020 / 31-03-2023



Investigador Principal: Juan Carlos Sánchez López
Organismo Financiador: Junta de Andalucia
Código: P18-RT-2641 "Frontera"

Equipo de Investigación: T. Cristina Rojas Ruiz, Belinda Siguenza Carballo

La mejora de los materiales empleados en los dispositivos usados en el campo de las energías renovables permitirá incrementar la eficiencia de los mismos haciéndolos más competitivos y rentables. El presente proyecto pretende desarrollar nuevos recubrimientos absorbedores selectivos de la energía solar aptos para trabajar a temperaturas superiores a las posibles con los materiales actualmente en uso en dispositivos de concentración solar térmica (500ºC en vacío – media concentración; 800ºC al aire – alta concentración). Los sistemas serán preparados en forma de multicapas por la novedosa tecnología de pulverización catódica donde los materiales son evaporados mediante impulsos de alta energía (HiPIMS - High Power Impulse Magnetron Sputtering). Los materiales preparados deberán cumplir los requisitos ópticos y de estabilidad química para soportar las condiciones de alta irradiación solar y temperaturas de trabajo. Este ambicioso proyecto se llevará a cabo mediante la colaboración de dos grupos de investigación pertenecientes al Instituto de Ciencia de Materiales de Sevilla CSIC-ICMS (grupo TEP958) y a la plataforma solar de Almería CIEMAT-PSA (Grupo TEP247). El grupo CSIC-ICMS se encargará del diseño, preparación y caracterización de los recubrimientos. Por su parte CIEMAT-PSA, diseñará y desarrollará los ensayos de campo, validando los recubrimientos en condiciones de trabajo similares a las de la aplicación final en términos de flujo solar concentrado incidente y temperaturas de operación. Dichos ensayos incluirán tanto determinación de parámetros térmicos y ópticos en condiciones nominales de operación, así como ciclado térmico de alta frecuencia (tratamiento térmico y envejecimiento).


Recubrimientos termocrómicos inteligentes para la climatización eficiente y el control ambiental (TOLERANCE)


01-01-2020 / 31-03-2023



Investigador Principal: Angel Barranco Quero / Alberto Palmero Acebedo
Organismo Financiador: Junta de Andalucia
Código: P18-RT-3480 "Frontera"

Equipo de Investigación: Ana María Gómez Ramírez, Juan Ramón Sánchez Valencia, Victor J. Rico Gavira, Rafael Alvarez Molina, Francisco Yubero Valencia, Juan Pedro Espinós Manzorro, Ana Isabel Borrás Martos, Agustín R. González-Elipe

La Agencia Internacional de la Energía considera que el uso sistemático de procedimientos autónomos de control ambiental representa una de las mejores apuestas tecnológicas para reducir el consumo energético asociado a la climatización de edificios (más del 40% del consumo global en países desarrollados, muy superior al porcentaje debido al transporte), reduciendo el impacto ambiental y mejorando además el confort habitacional. TOLERANCE persigue introducir y desarrollar en Andalucía la tecnología de los recubrimientos termocrómicos como elemento inteligente y autónomo de control de la irradiación solar en edificios. El interés de la propuesta se centra en nichos de aplicación como el cerramiento de edificios, el mobiliario urbano, la mejora de sistemas de producción de agua caliente sanitaria o la mejora de invernaderos. Un recubrimiento termocrómico se caracteriza por transmitir todo el espectro solar a bajas temperaturas y reflejar selectivamente parte de éste (el infrarrojo) a altas temperaturas. En esta línea, el proyecto propone diversas acciones de I+D para el desarrollo de capas delgadas con composición VO2, óxido termocrómico caracterizado con una temperatura de transición cercana a la temperatura ambiente, sobre vidrio y plásticos mediante técnicas escalables industrialmente, así como su nanoestructuración, dopado e integración en sistemas multicapas a fin de mejorar sus características y prestaciones multifuncionales.


Desarrollo de catalizadores y soportes para procesos de almacenamiento químico de energía neutros en CO2 basados en líquidos orgánicos portadores de hidrógeno


1-1-2019 / 30-09-2022



Investigador Principal: María Asunción Fernández Camacho
Organismo Financiador: Ministerio de Ciencia, Innovación y Universidades
Código: RTI2018-093871-B-I00 - "Retos Investigación"

Equipo de Investigación: María del Carmen Jiménez de Haro

El agotamiento de los combustibles fósiles (a corto y largo plazo) y el calentamiento global derivado del efecto invernadero son consecuencias del uso extensivo de estos combustibles. Por lo tanto, es muy conveniente utilizar y desarrollar energías renovables y así eliminar nuestra dependencia de los combustibles fósiles. Esto hace que el almacenamiento de energía producida por fuentes renovables (que son intermitentes) sea un objetivo importante de investigación. En proyectos anteriores, hemos trabajado en el estudio de nanomateriales y catalizadores para el almacenamiento de hidrógeno como vector de transporte y almacenamiento de energía (ciclo del H2). En este nuevo proyecto, el grupo de investigación propone avanzar en la Implementación de líquidos orgánicos como portadores de hidrógeno (LOHC) como una forma prometedora de combinar los ciclos del C02 y del H2 que conduzca a un almacenamiento de energía sostenible en un ciclo neutro en carbono. Pequeñas moléculas orgánicas, como el ácido fórmico o el metanol, se pueden usar para almacenar el H2 (y la energía) proveniente de fuentes renovables. Estos combustibles alternativos se pueden quemar o usarse para generar H2 que alimente directamente a una pila de combustible.
En este proyecto se llevarán a cabo investigaciones para la implementación de dos procesos relacionados con las tecnologías LOHC:
i) La descomposición térmica selectiva del ácido fórmico por catálisis heterogénea para la prodUCCión bajo demanda de hidrógeno exento de monóxido de carbono.
ii) La producción de hidrógeno por reformado de alcoholes (Le. biometanol) en procesos fotocatalíticos heterogéneos. La catálisis desempeña un papel clave en la implementación de estos dos procesos. Por lo tanto, los principales objetivos y actividades del proyecto son el diseño racional y la preparación de catalizadores y soportes para estudiar las relaciones composición-estructuradesempeño en los dos procesos mencionados anteriormente. El enfoque innovador es la aplicación de técnicas asistidas por plasma, como la pulverización catódica para el crecimiento de películas delgadas, y los tratamientos con plasmas de oxidación, reducción y grabado, para el desarrollo de recubrimientos catalíticos nanoestructurados y nanopartículas soportadas. Se desarrollarán espumas de carbono poroso y catalizadores basados en Pd que incluyen Pd, Pd-C, Pd-B o Pd-Cu para el estudio de la reacción de descomposición de ácido fórmico. Se investigarán películas fotocatalíticas de Ti02-TiOx con Pt (y/o Au) como co-catalizadores para el foto-reformado de metanol.


Arquitecturas de multicapas nanostructuradas para el desarrollo de dispositivos optofluídicos sensores y procesos de funcionalización superficial avanzada (NANOFLOW)


30-12-2016 / 29-06-2020



Investigador Principal: Angel Barranco Quero / Francisco Yubero Valencia
Organismo Financiador: Ministerio de Economía y Competitividad
Código: MAT2016-79866-R "Retos de la Sociedad"

Equipo de Investigación: Agustín R. González-Elipe, José Cotrino Bautista, Juan Pedro Espinós Manzorro, Fabián Frutos (US), Ana I. Borrás Martos, Alberto Palmero Acebedo, Victor Rico Gavira, Ricardo Molina (IQAC-CSIC), Fernando Lahoz (ULL), Xerman de la Fuente (ICMA-CSIC), Jesús Cuevas (US), M. Fe Laguna (UPM), Antonio Rodero (UCO), M. Carmen García (UCO)

NANOFlow es un projecto multidisciplinar que persigue el desarrollo de nuevos dispositivos optofluídicos mediante la integración de materiales nanostructurados multifuncionales. El proyecto está sólidamente fundamentado en la experiencia de los componentes del grupo de investigación en campos como la síntesis de películas multifuncionales, procesos avanzados de modificación de superficies y en el desarrollo de dispositivos fotónicos multicapa. El objetivo principal de este proyecto de investigación es combinar e integrar los distintos métodos avanzados de síntesis y procesado disponibles en la fabricación de dispositivos optofluídicos singulares que sean capaces de responder a la presencia de líquidos mediante un cambio físico. La combinación de este tipo de procesos de integración junto con el desarrollo de nuevos métodos de de detección fotónica, el uso de microplasmas de gran área como fuentes de luz y de sustratos flexibles que incorporan elementos sensores definen un conjunto muy rico de posibilidades de desarrollo de aplicaciones prácticas que se explorarán en el proyecto. Además, en el proyecto también se llevarán a cabo estudios de simulación de crecimiento de películas delgadas que, en combinación con estudios de diagnosis, permitirán ajustar los procesos de crecimiento para conseguir la funcionalidades requeridas. De esta forma, el proyecto NANOFlow intenta cubrir toda la cadena tecnológica que va desde el desarrollo de nuevos materiales hasta la aplicación final incluyendo estudios de caracterización, rutas sintéticas flexibles, búsqueda de procesos alternativos de bajo costo y alto rendimiento (por ejemplo métodos de fabricación empleando plasmas a presión atmosférica), integración de dispostivos y test de éstos en condiciones reales.

Las actividades de desarrollo planteadas en NANOFlow culminan en el desarrollo de tres tipos de dispositivos innovadores como son: las etiquetas inteligentes con actividad sensora y posibilidad de usarse como sistemas de trazabilidad y anticopia (por ejemplo integrados en el empaquetado de productos alimentarios), un dispositivos optofluídico multisensor versátil y un sistema de limpieza optofluídico fotocatalítico que integra una microplasma emisor de luz, interruptores ópticos de luz UV y visible actuados por líquidos y una superficie fotocatalítica nanoestructurada. Los tres dispositivos funcionan sobre la base de una actuación o respuesta optofluídica y están diseñados para poder usarse de forma directa en sistemas de detección, manipulación y monitorización de líquidos.

Las actividades de investigación en los distintos paquetes de trabajo del proyecto y los dispositivos finales se han propuesto para responder al Reto nº 2 de la convocatoria referida a  “Seguridad y calidad alimentaria”. Además, algunas de las actividades del proyecto, por ejemplo el tercer dispositivo, están también relacionados con el Reto nº 3 “Energía Segura, eficiente y limpia”. Es interesante indicar que las actividades propuestas en NANOFlow son de particular relevancia en el contexto geográfico de Andalucía donde la agricultura, la producción de alimentos y la energía son tres de los más relevantes sectores estratégicos.


Superficies super-hielofóbicas para prevenir la formación de hielo en aeroplanos


01-02-2016 / 31-01-2019



Investigador Principal: Agustín R. González-Elipe
Organismo Financiador: Union Europea
Código: H2020-TRANSPORT/0149






La acumulación de hielo representa un grave problema para los aviones, ya que la presencia incluso de una capa apenas visible puede limitar seriamente la funcionalidad de las alas, las hélices, los parabrisas, las antenas, las rejillas de ventilación, las tomas de aire y las cubiertas. El Proyecto PHOBIC2ICE tiene como objetivo desarrollar tecnologías y herramientas de simulación predictiva para evitar o mitigar este fenómeno.
El proyecto PHOBIC2ICE, mediante la aplicación de un enfoque innovador de simulación y modelado, permitirá el diseño y fabricación de superficies hielofóbicas con funcionalidades mejoradas. Se desarrollarán varios tipos de recubrimientos poliméricos, metálicos e híbridos usando diferentes métodos de deposición. Se prepararán superficies tratadas con láser y anodizadas. En consecuencia, el proyecto se centra en la recopilación de conocimientos fundamentales sobre los fenómenos asociados con los problemas de repulsión de hielo. Este conocimiento dará una mejor comprensión del proceso de acreción de hielo en diferentes superficies modificadas y recubiertas. La infraestructura de investigación certificada (túnel de viento de hielo) y las pruebas de vuelo previstas ayudarán a desarrollar soluciones integrales para abordar la cuestión de la formación de hielo y elevarán el nivel de innovación del Proyecto.
La solución propuesta será respetuosa con el medio ambiente, contribuirá a la reducción del consumo de energía y ayudará a eliminar la necesidad de procedimientos frecuentes de deshielo sobre suelo. Esto contribuirá a la reducción del coste, la contaminación y el retraso de vuelo. 

http://cordis.europa.eu/project/rcn/199478_en.html


Un proceso completo integrado de vacío y plasma para la síntesis de celdas solares de perovskita planares y en 1D


01-01-2016 / 31-12-2017



Investigador Principal: Angel Barranco Quero
Organismo Financiador: Union Europea
Código: H2020-MSCA-IF-2014, Project ID: 661480

Equipo de Investigación: Juan Ramón Sánchez Valencia

Las celdas solares (CS) –dispositivos que transforman luz en electricidad- han sido objeto de numerosos estudios en las últimas décadas ya que representan una prometedora vía para aprovechar la energía solar. Recientemente, las CS basadas en perovskita están recibiendo una gran atención debido a su bajo coste y alta eficiencia. Son muy prometedoras como alternativa a las actuales, pero aún necesitan avanzar para alcanzar más alta eficiencia, durabilidad y reproducibilidad, a la vez que requieren métodos de síntesis compatibles con la producción actual de dispositivos microelectrónicos a escala de oblea de silicio. Estas recientes CS son fabricadas usualmente por métodos húmedos que presentan desventajas como contaminaciones o reacciones químicas en las intercaras que pueden llevar a un deterioro del funcionamiento de la CS.

PlasmaPerovSol tiene como objetivo principal la fabricación de una celda solar de perovskita completa mediante un proceso integrado de vacío y plasma llevado a cabo bajo el concepto de un solo reactor. Los diferentes componentes de la CS se depositarán secuencialmente en un reactor de vacío evitando la exposición de los materiales e intercaras al aire o disolventes. La tecnología de deposición asistida por plasma desarrollada por el grupo receptor permite la fabricación de películas altamente conformales sobre una amplia variedad de templates.Esta aproximación se propone para fabricar multicapas conformales sobre materiales unidimensionales, con el que se mejorarán numerosos aspectos de las CS. Los procesos de vacío y plasma presentan como ventajas una alta reproducibilidad, pureza y control estequiométrico en la deposición. La síntesis propuesta es compatible con la producción a escala industrial y permite la fabricación de CS en sustratos procesables y flexibles. Al mismo tiempo, las bajas temperaturas utilizadas la hacen compatible con la tecnología actual de dispositivos microelectrónicos, y mediante el uso de máscaras permiten su integración en dispositivos preformados

http://cordis.europa.eu/project/rcn/196104_es.html

 


Desarrollo de catalizadores soportados sobre estructuras porosas para aplicaciones de generación y combustión catalítica de hidrógeno en el contexto de energías renovables


01-01-2016 / 31-12-2018



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Ministerio de Economía y Competitividad
Código: CTQ2015-65918-R

Equipo de Investigación: Asunción Fernández, Mª Carmen Jiménez de Haro, Vanda Godinho, Gisela Arzac, Dirk Hufschmidt, Rocio García

El agotamiento de combustibles fósiles a corto y medio plazo y los cambios climáticos producidos por el efecto invernadero son algunas de las principales consecuencias del uso extendido de estos combustibles. En este escenario el hidrógeno como vector de transporte y almacenamiento de energía es un candidato muy atractivo en el contexto de un mayor uso de las energías renovables y limpias. En consecuencia se plantean actualmente retos importantes para el desarrollo de tecnologías adecuadas,  tanto en la producción de hidrógeno libre de CO2, como en su transporte y almacenamiento seguro, y en su combustión eficiente para producir calor ó electricidad en una pila de combustible. Sobre la base de los proyectos previos del grupo en el estudio de hidruros complejos para almacenamiento de hidrógeno y en el desarrollo de catalizadores y procesos integrados  de generación y uso del hidrógeno en aplicaciones portátiles; se abordarán en este proyecto nuevas investigaciones  para desarrollar catalizadores novedosos soportados sobre estructuras porosas: membranas y espumas de materiales poliméricos, metálicos y cerámicos de alto interés actual. Los catalizadores se desarrollarán y estudiarán en reacciones seleccionadas de generación y combustión de acuerdo a las siguientes líneas de actuación:

1) Desarrollo de materiales novedosos con alto valor añadido del conjunto soporte-catalizador. Por un lado los soportes porosos basados en membranas de PTFE, espumas metálicas de Ni y espumas cerámicas de SiC. El objetivo es desarrollar los nuevos catalizadores sobre soportes de interés  como membranas separadoras, electrolitos, electrodos ó combustores de hidrógeno. Los nuevos catalizadores persiguen la reducción del uso de metales nobles (i.e. bimetálicos Pt-Cu, Ni-Fe) y el desarrollo de nuevos materiales metal-metaloide (carburos, boruros, etc.). Se usarán métodos químicos de impregnación, y muy especialmente la tecnología de deposición de películas delgadas,  pulverizacón catódica, que hemos aplicado recientemente con éxito a la fabricación de catalizadores de Co. La metodología abre un campo de investigación de gran interés al permitirnos el control de la microestructura y/o la composición (i.e. Co, Co-B, Co-C) de los catalizadores a demanda.

2) La caracterización microestructural y química de los nuevos materiales y catalizadores desarrollados en el proyecto. Se trata típicamente de materiales con una microestructura y nanoestructura controlada en donde las modernas técnicas nanoscopicas van a jugar un papel fundamental en la fabricación a medida de estos.

3) Estudio de actividad en tres ensayos catalíticos: i) la generación hidrolítica de hidrógeno, ii) la descomposición fotocatalítica del agua y iii) la combustión catalítica del hidrógeno. Todas ellas reacciones de alto interés en el contexto del uso del hidrógeno como vector de transporte y almacenamiento de energías renovables.

--Sobre la base de los resultados obtenidos en estas líneas de actuación, el proyecto se ha diseñado para alcanzar un conocimiento fundamental y un diseño racional en la nanoescala de catalizadores soportados en sustratos porosos. Las relaciones composición-estructura-propiedades se investigarán usando los ensayos catalíticos y fotocatalíticos acoplados a la microscopía electrónica de alta resolución analítica y otras técnicas espectroscópicas.


Recubrimientos para aplicaciones en energía y alta temperatura


01-01-2016 / 31-12-2019



Investigador Principal: Juan Carlos Sánchez López
Organismo Financiador: Ministerio de Economía y Competitividad
Código: MAT2015-65539-P

Equipo de Investigación: Iñigo Braceras Izaguirre (INASMET), Teresa Cristina Rojas Ruiz, Maria Belinda Sigüenza Carballo

La protección de las superficies frente a la temperatura, los fenómenos de oxidación o el desgaste ha logrado un progreso substancial mediante el desarrollo de nuevos materiales y recubrimientos con propiedades mejoradas tales como dureza extrema, baja fricción y tasas de desgaste, elevada resistencia ante la temperatura y la oxidación. Estas mejoras suponen un enorme ahorro de energía y reducción de costes debido a la vida media de los componentes mecánicos sin necesidad de sustitución, así como, a una reducción del impacto medioambiental. Este campo de investigación tiene una profunda repercusión en una gran variedad de sectores industriales (energía, herramientas de mecanizado, automoción, aeronáutico, metalurgia, etc.). El reto para la mayoría de estos procesos de funcionalización superficial residen en un control estricto de la micro y nanoestructura de la superficie y de las intercaras que hagan posible la aparición de nuevas propiedades y aplicaciones que la nanotecnología ofrece.

En este proyecto, se prepararán recubrimientos nanoestructurados para la protección de componentes sometidos a altas temperaturas y ambientes agresivos buscando un comportamiento mejorado. Este objetivo será abordado para tres diferentes aplicaciones que contribuirían a procesos energéticos más eficientes, energías renovables y soluciones para disminuir el impacto medioambiental. Basándonos en el sistema Cr-Al-N, se depositarán diferentes recubrimientos mediante la técnica de pulverización catódica reactiva cambiando la composición química (contenido en metal, incorporación de dopantes tales como Y o Si); microestructura; distribución de fases; arquitectura (multicapa/nanocomposite) o estructuras más complejas (tándem, multicapa en gradiente) sobre los sustratos apropiados dependiendo de la aplicación prevista: a) resistencia a la oxidación a alta temperatura (hasta 1000ºC) para herramientas; b) absorbedores solares selectivos estables térmicamente a medias (300-500ºC) y alta temperatura (>600ºC); resistencia a la corrosión para componentes en turbinas de vapor supercríticos (650ºC/100% vapor).

La investigación sobre los mecanismos de oxidación, transformaciones de fases, modificaciones estructurales, etc. serán objeto de un estudio detallado sobre los sustratos definidos para lograr un conocimiento fundamental sobre los procesos de degradación y los efectos protectores. El establecimiento de correlaciones entre las propiedades iniciales y el comportamiento funcional permitirá una mejor comprensión de los mecanismos de protección y por ende, una optimización de tales sistemas en forma de recubrimientos nanoestructurados para las aplicaciones previstas.

 

Palabras clave: Recubrimientos, alta temperatura, resistencia oxidación, corrosión, nanoestructurado, energía, absorbedor solar, multicapas


Válvulas de espín orgánicas e híbridas orgánica-inorgánicas en nanofibras soportadas, producidas por técnicas avanzadas de deposición en vacío y asistidas por plasma


01-10-2015 / 30-09-2017



Investigador Principal: Víctor López-Flores
Organismo Financiador: Junta de Andalucia
Código: TAPOST-234

Equipo de Investigación: Supervisor: Ana Borrás Martos. Componentes: Angel Barranco Quero, Francisco Aparicio, Juan Ramón Sánchez Valencia

La transición a la electrónica orgánica requiere de nuevos elementos en la escala nanométrica compuestos por materiales orgánicos, lo que proporciona dispositivos flexibles, transparentes y baratos. Entre los dispositivos electrónicos, las válvulas de espín han destacado por su rápida transición desde la fase experimental a los productos de uso común, pero aún no se ha fabricado una válvula de espín orgánica que sea fiable. El objetivo científico de este proyecto es llenar ese vacío. Mediante el uso de métodos nanotecnológicos avanzados y escalables industrialmente, pretendemos producir una válvula de espín híbrida orgánica-inorgánica, y puramente orgánica en la forma de una nanofibra soportada de 200 nm de grosor y varias micras de longitud, con la multicapa de la válvula de espín depositada concéntricamente. Las técnicas de fabricación principales seran la deposición física en fase vapor de materiales orgánicos (O-PVD), la deposición química en fase vapor asistida por plasma (PE-CVD), y la deposición en vacío asistida por plasma remoto (RPAVD). Las medidas de magnetoresistencia se efectuarán por microscopía de fuerza atómica con sonda conductora (CP-AFM), que dará la medida definitiva de la calidad de la muestra producida.

El proyecto se desarrollará en el gripo Nanotecnología en Superficies (NanoOnSurf) del Instituto de Ciencia de Materiales de Sevilla, localizado en el centro de investigación multidisciplinar CicCartuja (Sevilla, España). Las técnicas de síntesis y cartacterización más avanzadas, desarrolladas dentro del grupo de investigación serán la clave para el éxito de este proyecto.

Este proyecto está directamente relacionado con el Programa de Trabajo Horizonte 2020, capítulo 5.i (2014-2015), acción ICT3 – 2014: “Tecnologías avanzadas en electrónica delgada, orgánica y de gran área”, y por tanto se espera un gran impacto del mismo en el futuro de la industria electrónica europea.


Aplicación de técnicas avanzadas de microscopía electrónica para la caracterización de recubrimientos nano-estructurados para aplicaciones en energías limpias


01-03-2015 / 28-02-2017



Investigador Principal: Ana María Beltrán Custodio
Organismo Financiador: Junta de Andalucía
Código: TAHUB-050. Programa Talent HUB


Este proyecto se centra en la generación y almacenamiento de hidrógeno con el objetivo de producir hidrógeno para energías limpias. Esto sucede durante una reacción exotérmica en la que es necesaria la presencia de un catalizador para que se lleve a cabo en condiciones de seguridad. Los catalizados basados en metales nobles son buenos candidatos para este objetivo (cobalto, cobre…). Aquí, los sistemas completos catalizador-soporte son estudiados. Estos sistemas son crecidos mediante técnicas de pulverización catódica (“magnetron sputtering”). La estructura y la composición son estudiadas a escala nanométrica mediante técnicas avanzadas de microscopía electrónica de transmisión-barrido (STEM), como la microscopía electrónica de alta resolución (HRTEM), imágenes adquiridas en modo campo oscuro con detector de alto ángulo (HAADF), energía dispersiva de rayos X, espectroscopia de pérdida de energía de electrones (EELS), para análisis químico. Además, el uso de la técnica de caracterización tridimensional, tomografía electrónica, aporta un completo conocimiento del sistema analizado. La combinación de técnicas de análisis estructural y de composición, en modo TEM y STEM, nos permite obtener una completa nano-caracterización del sistema. Estos análisis STEM son una herramienta esencial para determinar la relación entre la microestructura, las condiciones de crecimiento y el comportamiento final y las propiedades del sistema, que nos ayudará a mejorarlos y, por tanto, contribuir a la producción de energía limpia.

Este proyecto tiene cuatro objetivos estratégicos.

1. Nano-materiales para aplicaciones en energía limpia. Materiales para la producción, uso y almacenamiento de hidrógeno.
2. Desarrollo de la técnica de magnetron sputtering para la fabricación de nano‑estructuras (capas delgadas, recubrimientos y micro-estructuras multicapas).
3. Potenciación de las facilidades LANE (Laboratorio de microscopía del centro ICMSE-CSIC).
4. Uso de técnicas avanzadas de caracterización estructural y de análisis para el estudio a nano-escala de nuevos nano-materiales. 


Desarrollo de procesos de combustión catalítica de hidrógeno y estudio de su integración en dispositivos para aplicaciones portátiles


16-05-2014 / 15-05-2016



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Junta de Andalucía
Código: P12-TEp-862

Equipo de Investigación: Julián Martínez, Gisela Arzac, Dirk Hufschmidt, Joaquín Ramírez, M.Carmen Vera, Vanda Godinho, Lionel Cervera, T.Cristina Rojas, Olga Montes, Mariana Paladini, Jaime Caballero-Hernández

El hidrógeno como vector de transporte y almacenamiento de energía es un candidato muy atractivo en el contexto de un mayor uso de las energías renovables y limpias. La producción y el uso de la energía basada en la tecnología del hidrógeno es de especial relevancia en pequeña escala para aplicaciones portátiles (y potencialmente escalable para aplicaciones estacionarias). En el presente proyecto se abordará el estudio del proceso de combustión catalítica o controlada de hidrógeno en los distintos aspectos que puedan conducir a una configuración final integrada con un sistema de generación de H2 en aplicaciones portátiles. Para ello se aprovecharán las sinergias integrando investigadores de dos grupos del PAI: i) Del grupo TEP217, especialistas en almacenamiento y generación de hidrógeno en sistemas basados en hidruros metálicos, hidruros complejos y composites de hidruros reactivos; así como en el uso de catalizadores y aditivos para controlar y mejorar las cinéticas de estos procesos. ii) Del grupo FQM342, especialistas en la obtención de cerámicos porosos de alto interés como soportes de catalizadores en entornos agresivos de combustión. Además la colaboración se completa con la participación de la empresa Abengoa Hidrógeno S.A. que participa en calidad de subcontratada como especialistas en sistemas de producción y almacenamiento de hidrógeno.
En particular se trabajará en este proyecto en las siguientes líneas de actuación:
1.- Desarrollo de catalizadores y soportes para la combustión controlada. Típicamente cerámicas porosas biomórficas de carburo de silicio y catalizadores clásicos tipo metal noble y nuevos catalizadores de bajo coste a desarrollar en el proyecto.
2.- Desarrollo de los reactores necesarios para el estudio de la combustión controlada. Típicamente para flujos de hidrógeno de unos pocos ml/min y para la escala de un generador de H2 ya disponible de 0.5 a 1.5 L/min.
3.- Acoplamiento al sistema de combustión controlada de los sistemas portátiles de generación de hidrógeno que hemos desarrollado en proyectos anteriores.
4.- Aplicación de la tecnología de pulverización catódica de una manera exploratoria en este proyecto para depositar los catalizadores de combustión catalítica en sustratos porosos.
5.- Caracterización microestructural y química de los soportes y catalizadores en la nanoescala para seguir los procedimientos de síntesis y evolución en operación.
 


Plasmas de Descarga de Barrera Dieléctrica para el Desarrollo de Procesos Industriales a Presión Atmosférica (Dbd-Tech)


30-01-2014 / 29-01-2017



Investigador Principal: José Cotrino Bautista
Organismo Financiador: Junta de Andalucía
Código: P12-FQM-2265 (Proyecto de Excelencia)

Equipo de Investigación: Francisco José García García, Jorge Gil Rostra, Richard M. Lambert, Manuel Macías Montero, Alberto Palmero Acebedo, Victor Rico Gavira

La presente propuesta de proyecto de investigación persigue en primera instancia abordar una serie de aspectos básicos no resueltos relacionados con los mecanismos de la descarga barrera, las condiciones óptimas que deben cumplir los electrodos, la definición de un diseño óptimo de los mismos y el establecimiento de las mejores condiciones para la descarga.

En una segunda instancia y desde una perspectiva aplicada, se pretende la fabricación de dos tipos de reactores de descarga barrera mejorados para dos aplicaciones tecnológicas de gran impacto industrial. Primeramente para la funcionalización superficial de materiales avanzados persiguiendo, entre otros, el control lateral de la funcionalización según patrones litográficos. En segundo término, para el desarrollo de procesos de “plasma-catálisis” tendentes a aumentar la selectividad y disminuir el consumo energético de una serie de reacciones químicas de alto valor añadido e impacto industrial. Se prevé que, para ambos tipos de aplicaciones, los estudios básicos planteados permitan avanzar de manera clara en la optimización de los procesos finales con perspectivas de uso industrial.


Control ambiental y de procesos con dispositivos responsivos con capas nanoestructuradas fabricadas por tecnologías innovadoras de vacio y plasmas


01-01-2014 / 31-12-2017



Investigador Principal: Agustín R. González-Elipe
Organismo Financiador: Ministerio de Economía y Competitividad
Código: MAT2013-40852-R

Equipo de Investigación: José Cotrino Bautista, Ricardo Molina Mansilla, Victor Rico Gavira, Francisco Yubero Valencia, Juan Pedro Espinós Manzorro, Alberto Palmero Acebedo, Angel Barranco Quero, Fernando Lahoz Zamarro

Este proyecto persigue el desarrollo de una nueva generación de sistemas responsivos y sensores de baja dimensión que integren capas delgadas nanoestructuradas con propiedades ópticas y eléctricas controladas preparadas mediante técnicas innovadoras de vacío y plasma. Los principios básicos de la deposición física en fase vapor (PVD) en configuración oblicua (OAD) se extenderán a técnicas de plasma y de pulverización catódica para producir capas con porosidad controlada que interactúen  eficientemente con el medio. Se propone también la combinación de estas técnicas con otras tecnologías novedosas de plasma, como  la deposición por plasma a presión atmosférica o mediante evaporación-polimerización, para conseguir un control estricto sobre la nanoestructura y las propiedades finales de sistemaas complejos. Mediante estas tecnologías se prepararán capas finas nanoestructuradas de metales y óxidos, multicapas apiladas y nanoestructuras tipo "composites" e híbridas que, a continuación, se caracterizarán mediante microcopías electrónicas avanzadas y de proximidad, entre otras técnicas. Para encontrar nuevas rutas de procesado de capas porosas con morfologías y propiedades "a medida" y posibilitar su escalado a nivel industrial, se propone estudiar los mecanismos fundamentales que gobiernan el crecimiento de las películas a fin de modificarlos convenientemente. Conjuntos  ordenados y homogéneos de estas estructuras se emplearán como sensores de gases y líquidos a temperatura ambiente, dispositivos microfluídicos responsivos y etiquetas inteligentes. Para estas y otras aplicaciones, las capas finas porosas soportadas se funcionalizarán convenientemente con nanopartículas metálicas, cadenas moleculares ancladas o capas de  materiales poliméricos. Asímismo, se contempla su apilamiento en forma de estructuras fotónicas verticales.  Para la implementación de estas estructuras en forma de micro-dispositivos  que actúen como sensores avanzados, se desarrollarán microreactores y sistemas responsivos mediante estrategias novedosas de integración, basadas en la deposición mediante evaporación de capas eliminables de NaCl. Estos sistemas incluirán también transductores fotónicos, eléctricos y/o electroquímicos que permitan el desarrollo de dispositivos finales capaces de detectar i) oxígeno y cloro en disolución, ii) glucosa y materia orgánica en el agua, iii) vapores y gases  en aire, o iv) etiquetas inteligentes que cambien como respuesta al medio.  Se prevén aplicaciones específicas para el control del medio ambiente en aire y aguas, emplazamientos industriales e invernaderos, procesos agroindustriales  tales como la fermentación, así como para el seguimiento y la trazabilidad de diferentes tipos de mercancías y alimentos. Se espera que la combinación de nuevos descubrimientos científicos en el campo de la tecnología de capas delgadas y el de nuevos principios de integración a las escalas micro y nano abran nuevas áreas de investigación con alto impacto en diversos campos y tecnologías facilitadoras tales como la fotónica, la nanotecnología o los materiales avanzados, así como en tecnología de plasma y microfluídica.     


Nuevas nanoestructuras 1d-híbridas multifuncionales para el desarrollo de nanosistemas autoalimentados


1-01-2014 / 31-12-2016



Investigador Principal: Ana Isabel Borrás Martos
Organismo Financiador: Ministerio de Economía y Competitividad
Código: MAT2013-42900-P

Equipo de Investigación: José Cotrino Bautista, Ricardo Molina Mansilla, Juan Pedro Espinós Manzorro, Ana Isabel Borrás Martos, Angel Barranco Quero

HYBR(1)D es un proyecto de carácter multidisciplinar en el que se persigue el desarrollo de nuevos materiales nanoestructurados multifuncionales que encuentren aplicación final en campos como las energías renovables, fotónica y la miniaturización de dispositivos. En el proyecto se plantea como principal objetivo el desarrollo de métodos de fabricación de nuevos materiales unidimensionales nanoestructurados como nanocables orgánicos e inorgánicos y sistemas unidimensionales heteroestructurados e híbridos. Haciendo especial hincapié en sistemas compuestos del tipo coaxial "core@shell/multi-shell" que integren componentes orgánicas, metales y óxidos. Estos materiales serán fabricados mediante una innovativa metodología que permiten su formación sobre sustratos procesables de distinta naturaleza involucrando tecnologías escalables industrialmente. Además se propone de forma exploratoria la fabricación de membranas "compuestas" que permitan el uso de estas nanoestructuras embebidas de forma autosoportada. El segundo objetivo de este proyecto es probar la funcionalidad de estas nuevas nanoestructuras en distintas aplicaciones atendiendo al concepto de “nanosistema autoalimentado”: como sistemas de generación de energía (celdas solares y piezoelectricidad) y nanosensores. Cabe resaltar que aunque los materiales a fabricar son muy diversos, desde nanotubos de semiconductores inorgánicos (TiO2 y ZnO) a nanohilos orgánicos ("small-molecule single crystal nanowires) híbridos y heteroestruturados, los métodos de fabricación que se pretenden utilizar se basan en técnicas de vacío muy similares y facilmente acoplables. Así, las distintas nanoestructuras y heteroestructuras se fabricarán mediante cuatro técnicas principales y combinaciones de las mismas: deposición física desde fase vapor aplicada a moléculas orgánicas, deposición química desde fase vapor asistida por plasma de moléculas orgánicas y óxidos semiconductores, sputtering-dc de metales y "etching" por plasma de oxígeno. El IP y el grupo Nanotechnology on Surfaces del ICMS tienen un amplio background en la aplicación de estas técnicas para el desarrollo de sistemas del tipo láminas delgadas y recubrimientos funcionales, experiencia que se ha extendido en los últimos años al estudio de nanoestructuras 1D soportadas. El proyecto aborda toda la cadena de valor que lleva desde la síntesis de nuevos materiales a sus aplicaciones, incluyendo su caracterización avanzada e integración en dispositivos y prototipos a escala de laboratorio.


Nuevos materiales para envasado, etiquetado inteligente, control de fraudes y monitorización visual del estado de los productos


02-12-2013 / 31-12-2015



Investigador Principal: Angel Barranco Quero
Organismo Financiador: Ministerio de Economía y Competitividad
Código: RECUPERA2020 - 1.4.2

Equipo de Investigación: Ana Isabel Borrás, Francisco Yubero, José Cotrino, Juan Pedro Espinós, Juan Ramón Sánchez Valencia, Francisco Javier Aparicio Rebollo

En esta actividad se pretende desarrollar una serie de nuevos materiales y procesos basados en marcado por láser para el desarrollo de un nuevo sistema de marcaje y etiquetado “inteligente” capaz de lograr una mejora en los procesos de control y de la trazabilidad de productos agropecuarios.


Purificación del aire en invernaderos y centros de tratamiento de alimentos


2-12-2013 / 31-12-2015



Investigador Principal: José Cotrino Bautista
Organismo Financiador: Ministerio de Economía y Competitividad
Código: RECUPERA2020 - 2.2.3

Equipo de Investigación: Ana María Gómez Ramírez, Antonio Méndez Montoro de Damas

Este proyecto está relacionada con una tecnología para generar un plasma frío a presión atmosférica con aire que fluye a través de un reactor. El objetivo específico de esta actividad es el desarrollo de un sistema prototipo de purificación de aire para invernaderos, centros de procesamiento de alimentos, recintos para el ganado u otros tipos similares en mercados o recintos donde la concentración de gases nocivos para la salud de los trabajadores puede ser muy significativa por el uso de insecticidas, fungicidas, desinfectantes y otros compuestos. El sistema desarrollado debe ser capaz de purificar el aire en instalaciones cerradas y donde un gran número de productos químicos, compuestos orgánicos volátiles, principalmente, se acumulan en el aire del establecimiento. El diseño de la tecnología del reactor de plasma frío sigue las características de descarga de barrera dieléctrica con dieléctrico en forma de lecho empaquetado utilizando materiales dieléctricos de carácter ferroeléctrico con elevada constante dieléctrica.


Sensores micro-fluídicos integrados para el control de la fermentación


2-12-2013 / 31-12-2015



Investigador Principal: Agustín R. González-Elipe
Organismo Financiador: Ministerio de Economía y Competitividad
Código: RECUPERA2020 - 1.4.1

Equipo de Investigación: Juan Pedro Espinós Manzorro, José Cotrnio Bautista, Francisco Yubero Valencia, Alberto Palmero Acebedo, Angel Barranco Quero, Ana I. Borrás Martos, Victor J. Rico Gavira, Rafael Alvarez Molina, Pedro Angel Salazar Carballo

El objetivo de este proyecto es el desarrollo de nuevos sistemas micro/nano fluídicos integrados y robustos que permitan la incorporación fiable de tests de control, sensorización y/o análisis rápido de productos agroalimentarios, fundamentalmente líquido o productos solubles. La tecnología a desarrollar se intenta aplicar tanto para el control de productos finales como durante las etapas de elaboración de los mismos. En concreto, un nicho de aplicación que directamente que se abordará dentro del proyecto es el control de procesos de fermentación, con el desarrollo de nuevos transductores fluídicos integrados que permitan la detección cuantitativa de glucosa y/o otros azúcares mediante desarrollos electroquímicos y fotónicos en dispositivos microfluídicos y similares.


Dispositivos luminiscentes basados en láminas delgadas con tierras raras depositadas mediante tecnología de plasma (LUMEN)


16-05-2013 / 15-05-2016



Investigador Principal: Angel Barranco Quero
Organismo Financiador: Junta de Andalucía
Código: P11-TEP-8067 (Proyecto de Excelencia Motriz)

Equipo de Investigación: Agustín R. González-Elipe, Juan Pedro Espinós, Richard Lambert, Juan Carlos González-González, Francisco J. García García, Victor J. Rico Gavira, , Jorge Gil Rostra, Lola González García, F. Javier Ferrer (CNA), Fabián Frutos Rayego

El presente proyecto persigue el desarrollo de una serie de dispositivos luminiscentes basados en láminas delgadas con tierras raras depositadas mediante tecnologías de plasma. Las láminas delgadas luminiscentes se fabricarán mediante un nuevo procedimiento desarrollado por el grupo investigador que combina procesos clásicos como “magnetrón sputtering” o deposición por plasma y la evaporación de compuestos metalorgánicos de baja o nula tensión de vapor a temperatura ambiente pero fácilmente sublimables en la cámara de reacción. Esta metodología ofrece la oportunidad de integrar uno o varios elementos de tierras raras dentro de la capa formada, controlando perfectamente su concentración en la misma. Dada la versatilidad del proceso, se plantea fabricar capas delgadas luminiscentes de interés para tres campos de aplicación: procesos de “up conversión”, detectores de ion-luminiscencia y sistemas de señalización. Los materiales a desarrollar deben permitir superar algunas de las limitaciones existentes con los materiales actualmente existentes, proporcionando nuevas funcionalidades y mejoras sustanciales en sus prestaciones en relación con aplicaciones como detectores en procesos de fusión nuclear, cambiadores de longitud de onda en sistemas para comunicaciones ópticas y señalización en automoción.  Dadas las características del nuevo método propuesto, el proceso de síntesis de las capas luminiscente es compatible con otros procesos en línea proponiéndose la integración de las capas luminiscentes en dispositivos fotónicos simples formadas por estructuras multicapa tipo reflectores de Bragg o similares.  El proyecto aborda todo la cadena de valor que lleva de la síntesis de los materiales a sus aplicaciones, incluyendo su caracterización avanzada, el análisis de sus propiedades ópticas y de luminiscencia, su integración en dispositivos y el análisis de su resistencia medioambiental.


Desarrollo de nuevos materiales y procesos para la generación y uso del hidrógeno principalmente en aplicaciones portátiles


01-01-2013 / 31-12-2015



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Ministerio de Economía y Competitividad
Código: CTQ2012-32519

Equipo de Investigación: Gisela Arzac, Jaime Caballero, Lionel Cervera, Vanda Fortio, Carlos Negrete, Dirk Hufschmidt, Cristina Rojas Ruiz, Roland Schierholz

El hidrógeno como vector de transporte y almacenamiento de energía es un candidato muy atractivo en el contexto de un mayor uso de las energías renovables y limpias. En el presente proyecto se abordará el estudio de los distintos procesos que conducen a la configuración final integrada de sistemas de generación y uso del hidrógeno principalmente en aplicaciones portátiles (y potencialmente escalables para aplicaciones estacionarias). En particular se trabajará en este proyecto en las siguientes líneas de actuación:
a) Investigación en nuevos compuestos ligeros para su uso en procesos de generación de hidrógeno en pequeña escala por vía química (hidrólisis). Típicamente reacciones de hidrólisis de borohidruros (i.e. NaBH4) y compuestos tipo borano de amoníaco, hidrazinas ó borano hidrazina. Este area incluye el desarrollo de catalizadores en la nanoescala utilizando métodos de vía húmeda para su síntesis: Nanoestructuras metal-metaloide (tipo Co-B, Co-B-P y similares) y catalizadores bimetálicos (que incluyan ó no metaloide) de bajo coste potenciando efectos sinérgicos (tipo CoRu, NiPt ó Co-Ru-B). Incluye también el desarrollo de reactores portátiles para estos procesos y el desarrollo de nuevos sustratos y monolitos, estudios de adherencia del catalizador y durabilidad.
b) Investigación en nuevos sistemas anfitrión-huésped (host-guest) que contengan hidrógeno para el almacenamiento reversible (carga/descarga). Principalmente soportes (anfitrión) porosos del tipo “nanoscaffolds” (basados en C ó BN) infiltrados con borohidruros (huésped) (i.e. borohidruro de titanio) típicamente utilizados para el almacenamiento reversible de hidrógeno. Estos nuevos materiales deben presentar cinéticas de carga y descarga mejoradas.
c) Estudios de acoplamiento de un sistema generador de hidrógeno de bajo coste a una celda de combustible. Típicamente un reactor continúo para la hidrólisis del NaBH4 con catalizador Co-B que suministra H2 en condiciones de flujo constante para alimentar directamente una pila de combustible tipo PEM de 60 W.
d) Estudios fundamentales para el desarrollo de catalizadores y soportes para la combustión controlada de hidrógeno. Es una línea nueva en el grupo de investigación que se basa en preparar por vía húmeda catalizadores nanoparticulados de metal noble sobre soportes comerciales de cerámicas porosas (tipo SiC). Incluye el diseño de un reactor para el estudio en escala laboratorio de la producción de calor por combustión controlada de hidrógeno.
e) Desarrollo de la tecnología de pulverización catódica (“magnetrón sputtering”) para la preparación de catalizadores y nano-estructuras sobre diversos sustratos de aplicación en los procesos desarrollados en los apartados anteriores. El grupo tiene una amplia experiencia en esta tecnología que se aplicaría de manera novedosa en este proyecto permitiendo una gran versatilidad en cuanto a la nanoestructura, composición y aditivos para mejorar la actividad, durabilidad y selectividad de los catalizadores.
f) Caracterización microestructural y química de los nuevos materiales y catalizadores desarrollados en el proyecto. Se trata típicamente de materiales con una nanoestructura controlada en donde las modernas técnicas nanoscopicas van a jugar un papel fundamental en la fabricación a medida de estos materiales.
 


Arquitecturas SOFC innovadoras basadas en operación "Triodo"


01-09-2012 / 29-02-2016



Investigador Principal: Agustín R. González-Elipe
Organismo Financiador: Unión Europea
Código: FCH-JU-2011-1

Equipo de Investigación: Francisco Yubero Valencia, Juan Pedro Espinós Manzorro, Angel Barranco Quero, Richard Lambert, Victor J. Rico, Ana Borrás Martos, José Cotrino, Jorge Gil, Pedro Castillero, Fran J. García, Alberto Palmero

El desarrollo de celdas de combustible de óxido sólido (SOFCs) que operen con hidrocarburos como combustibles (gas natural, biocompustibles, LPG) es esencial para la comercialización a plazos cortos y medios. El desarrollo de HC SOFCs directas se enfrenta todavía a numerosos retos y problemas que surgen del hecho que los materiales del anodo operan bajo condiciones muy severas. Estas limitan el rendimiento con reacciones de reformado u oxidación, producen una desactivación rápida debido a la contaminación con carbón y generan inestabilidad asociada a la presencia de compuestos de azufre. Aunque la investigación en estos temas es intensa, no se han producido avances tecnológicos significativos respecto a mejorar la robustez del proceso, el incremento de su tiempo de vida y a la disminución de su costo.

T-CELL propone una aproximación electroquímica novedosa con el fin de abordar estos problemas mediante un esfuerzo integrado para definir, explorar, caracterizar, desarrollar y ejecutar una aproximación a la tecnología SOFC radicalmente nueva basada en una aproximación tipo “triodo”. Para ello se desarrollará una aproximación integrada basada en el desarrollo de materiales y en la aplicación de un diseño de celda innovador que permite el control efectivo de la actividad electrocatalítica bajo vapor o condiciones de reformado en seco.
La novedad del trabajo propuesto reside en el esfuerzo pionero para desarrollar nuevos materiales a base de Ni que actúen como ánodo y que presenten tolerancia al envenenamiento, así como en el desarrollo del concepto de triodo aplicado a celdas SOFC para incorporar una nueva variable en la operación de celdas de combustible.
Para demostrar la posibilidad de apilamiento en las celdas triodo, se desarrollará un apilamiento SOFC tipo triodo formado por cuatro unidades repetidas. Este sistema se evaluará con metano y vapor en presencia de una pequeña concentración de compuestos de azufre.

http://cordis.europa.eu/project/id/298300/es


Capas nanoestructuradas tribológicas para funcionamiento en vacío o atmósfera variable


01-01-2012 / 31-12-2014



Investigador Principal: Juan Carlos Sánchez López
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: MAT2011-29074-C02-01

Equipo de Investigación: Cristina Rojas Ruiz, Carlos López Cartes (US), Francisco Javier Pérez Trujillo (UCM)

Desarrollo de recubrimientos nanoestructurados protectores para su uso en condiciones extremas (NANOPROTEXT)


01-01-2012 / 31-12-2014



Investigador Principal: Juan Carlos Sánchez López
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: MAT2011-29074-C02-01

Equipo de Investigación: T. Cristina Rojas Ruiz; Francisco Javier Pérez Trujillo;Maria del Pilar Hierro de Bengoa;Germán Alcalá Penades; Maria Sonia Mato Díaz; Marta Brizuela; Pablo Corengia; José Luis Viviente; Alberto García;Daniel González

En muchas operaciones industriales, los componentes de las maquinas o piezas que están en contacto se hallan sometidos a condiciones extremas de carga, fricción, temperatura o atmósfera variable. La investigación dirige sus esfuerzos hacia al desarrollo de nuevos recubrimientos multicomponentes capaces de aumentar su eficiencia protegiendo su superficie contra el desgaste y la oxidación, que ocasionan fallos ulteriores de funcionamiento. Mediante el control del tamaño y distribución de las fases componentes, la composición química y su microestructura en el rango nanométrico es posible obtener propiedades multifuncionales tales como baja fricción, dureza y estabilidad térmica.
En este proyecto se propone el desarrollo de tres tipos de recubrimientos nanoestructurados mediante el proceso de magnetron sputtering para aplicaciones protectoras en condiciones extremas o singulares de funcionamiento (presión, temperatura, atmósferas oxidantes, vacío, etc). Los sistemas elegidos comprenden cristales de materiales duros (nitruros o carburos) combinados con una segunda fase o elemento que mejore su comportamiento. De este modo se ensayarán recubrimientos nanocomposite formados por nanocristales de WC dispersos en una segunda fase amorfa de tipo calcogenuro (WS2 or WSe2) para su uso como lubricante sólido en aplicaciones espaciales o bajo atmósferas inertes. En el segundo caso, Y ó Zr serán usados como elementos dopantes dentro de recubrimientos de CrAlN con objeto de incrementar la resistencia a la oxidación a baja y alta temperatura, y el comportamiento tribológico, muy válido en numerosos sectores industriales tales como (herramientas de mecanizado, metalúrgico, aeronaútico, automoción, etc.). Finalmente, se desarrollaran recubrimientos nanocomposite duros y transparentes basados en la familia del Al-Si-N para protección de sistemas ópticos.
En todos los casos, el proyecto comprende su síntesis, caracterización estructural y química, así como su validación práctica en ensayos tribológicos y de oxidación que simulan las condiciones finales de operación. En el caso concreto de las capas duras y transparentes también se evaluarán sus propiedades ópticas. El estudio de la relación existente entre la microestructura y las propiedades medidas será un objetivo esencial puesto que permitirá una mayor comprensión de los mecanismos de actuación, y por ende, la optimización de tales sistemas nanoestructurados para su mejor aprovechamiento tecnológico.
 


Laboratorio avanzado para el análisis de nanomateriales funcionales


01-10-2011 / 30-03-2015



Investigador Principal: María Asunción Fernández Camacho
Organismo Financiador: Unión Europea
Código: REGPOT-CT-2011-285895

Equipo de Investigación: T. Cristina Rojas, M.Carmen Jiménez, Gisela Arzac, Olga Montes, Inmaculada Rosa, Rafael Alvarez, Vanda Godinho, Juan Carlos Sánchez-López, Hernán Míguez, Agustín R. González-Elipe, Manuel Ocaña, M. Jesús Sayagués, Lionel Cervera, Roland Schierholz, Salah Rouillon, Lucia Castillo, Rocío García, Carlos García-Negrete, Jaime Caballero

El proyecto AL-NANOFUNC ha sido diseñado para poner en marcha en el Instituto de Ciencia de los Materiales de Sevilla (ICMS, CSIC-Univ.Sevilla, España) un laboratorio avanzado para el Nano-análisis de nuevos materiales funcionales. Las técnicas de Nanoscopía avanzada, basadas en equipos de microscopía electrónica de última generación, se dedicarán a la investigación de vanguardia en temas específicos de gran interés: i) Nanomateriales para aplicaciones energéticas sostenibles; ii) películas delgadas multifuncionales y recubrimientos nanoestructurados; iii) materiales nano-estructurados para fotónica y sensores. Para situar a los laboratorios del ICMS en una posición de liderazgo que sea competiti-va en un escenario mundial, el proyecto AL-NANOFUNC contempla la puesta al día del poten-cial investigador actual en varias direcciones: i) Mejorar las capacidades de equipamiento en relación a la microscopía electrónica analítica de alta resolución; ii) mejorar el impacto de la investigación básica a través de la contratación de investigadores especializados y el intercambio transnacional con los centros de referencia en Europa, iii) desarrollar y mejorar el potencial de innovación de la investigación del ICMS abriendo las nuevas instalaciones a empresas y centros relacionados; iv ) organizar talleres, conferencias y actividades de difusión para mejorar la visibilidad de la investigación. En el proyecto se propone también una estrecha colaboración con centros de referencia y empresas de Lieja (Bélgica), Graz (Austria), Jülich (Alemania), Oxford (Inglaterra), Cambridge (Inglaterra), Dübendorf (Suiza) y Rabat (Marruecos), así como con laboratorios de Universidades Andaluzas. Cinco empresas en Andalucía colaborarán también en estrecha sinergia para promover las líneas estratégicas de interés a largo plazo de la región en los productos de piedra natural y artificial y los sectores de energía solar y energías renovables.


Recubrimientos nanoestructurados para operar en vacío


01-10-2011 / 31-12-2011



Investigador Principal: Juan Carlos Sánchez López
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: MAT2010-21597-C02-01

Equipo de Investigación: T. Cristina Rojas Ruiz, Santiago Domínguez Meister

En este proyecto se desarrollarán recubrimientos nanoestructurados por la técnica de magnetron sputtering para lubricación de componentes mecánicos en aplicaciones aeroespa-ciales. Estos materiales deben proporcionar protección frente al desgaste y baja fricción cuando se usen en condiciones atmosféricas o vacío. Los sistemas elegidos para lograr este compromiso están formados por nanocristales de WC dispersados en una fase amorfa de dicalcogenuro (WS2 or WSe2). Estos lubricantes se esperan que pueden mejorar la resistencia al desgaste, mecánica y a la oxidación en comparación con los recubrimientos convencionales (MoS2 or DLC) usados para estos fines.


Desarrollo de recubrimientos y andamios bioactivos de material cerámico nanoestructurado para la regeneración ósea (BIOCEREG)


06-07-2011 / 05-06-2016



Investigador Principal: María Aránzazu Díaz Cuenca
Organismo Financiador: Junta de Andalucía
Código: CTS-661

Equipo de Investigación: M. Lourdes Ramiro Gutiérrez, Sara Borrego González

Este Proyecto pretende contribuir al avance en el desarrollo de nuevos biomateriales con bioactividad mejorada para su aplicación en la reparación y regeneración ósea. Se propone la preparación de nuevos recubrimientos y andamios cerámicos mediante técnicas de procesado láser a partir de materiales cerámicos particulados, nanoestructurados de composición bioactiva en el sistema SiO2-CaO-P2O5 sintetizados en el ICMS por la Dra. Díaz (IP de esta solicitud). La hipótesis de partida es que las características nanoestructurales y texturales del material cerámico particulado en combinación con la fuente láser tiene un gran potencial para resultar en deposiciones con microestructura y nanoestructura controlada. Se plantea procesar dos tipos de pieza prototipo: i) piezas de sustrato metálico (de titanio) con recubrimiento cerámico de composición bioactiva y ii) piezas monolito (andamio) solo cerámica bioactiva con geometría controlada. Hay que distinguir por tanto la persecución de dos hitos. Un primer Hito es la obtención de materiales prototipo (recubrimientos y andamios) con unos requerimientos de micro y nanoestructura, superficie, propiedades mecánicas, homogeneidad y reproducibilidad mínimas. Y un segundo Hito consistente en la verificación de sus propiedades biológicas in vitro e in vivo. El éxito en ambos hitos es lo que finalmente denominaremos biomaterial prototipo. La obtención de los recubrimientos tendría una translación muy directa para implementarse en distintas partes de los componentes de implantes ortopédicos. En este sentido el equipo de investigación integra a biólogos de regeneración esquelética y clínicos de cirugía ortopédica y traumatología que van a estudiar la bioactividad y biocompatibilidad de estos recubrimientos sobre sustratos de titanio suministrados por Synthes, empresa líder en fabricación y comercialización de implantes para ortopedia, que participa en esta propuesta como EPO. Por otra parte y desde el punto de vista del procesado de materiales, la aplicación del procesado láser a los materiales cerámicos nanoestructurados SiO2-CaO-P2O5 es totalmente novedoso y creemos que puede optimizarse para obtener recubrimientos y también andamios tridimensionales, conformados con macroporosidad interconectada pero a su vez con microestructura fina y nanoestructura, que culminen en la obtención de piezas prototipo con alta reproducibilidad y de calidad e innovación tecnológica elevada. El Proyecto se encuadra en áreas de investigación fuertemente innovadoras y pujantes como son la nanotecnología y la medicina regenerativa ambas con un carácter multidisciplinar intrínseco donde la frontera entre las distintas disciplinas científicas tradicionales aparece difuminada. El Proyecto aúna esfuerzos de investigadores con formación básica en las disciplinas de química (ICMS), física e ingeniería (Empresa Subcontratada AIMEN), biología (UMA-CIBER-BBN) y medicina clínica y traslacional (HCS). Creemos que la integración de estos tres pilares i) síntesis, procesado y caracterización de materiales, ii) biología de la regeneración e ingeniería tisular y iii) práctica clínica ofrece una propuesta con capacidad para aportar resultados de impacto trasferibles a la industria y que puede por tanto ayudar al desarrollo de productos para aplicaciones en la reparación y rege-neración esquelética en Andalucía.


Sol y Visión par la energía térmica actual. SOLVENTA


4-05-2011 / 31-12-2014



Investigador Principal: Agustín R. González-Elipe
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: Proyecto INNPACTO - IPT-2011-1425-920000

Equipo de Investigación: Francisco Yubero Valencia, Juan Pedro Espinós Manzorro, Angel Barranco Quero, Victor J. Rico, Ana Borrás Martos, José Cotrino, Jorge Gil, Pedro Castillero, Fran J. García

Este proyecto persigue el desarrollo de una serie de equipos y dispositivos para la monitorización de las condiciones de funcionamiento de plantas termosolares de concentración con espejos cilíndrico-parabólicos. La participación del ICMSE se centra en la aplicación tecnologías de plasma y el desarrollo de sistemas en lámina delgada capaces de diagnosticar las condiciones de funcionamiento de dichas instalaciones.


Control de procesos en plasmas para la síntesis de materiales nanoestructurados en forma de láminas delgadas (PLASMATER)


15-03-2011 / 14-03-2014



Investigador Principal: Alberto Palmero Acebedo
Organismo Financiador: Junta de Andalucía
Código: P09-FQM-6900

Equipo de Investigación: José Cotrino Bautista, Ana Borrás Martos, Francisco Yubero Valencia, Rafael Alvarez Molina, Juan Carlos González González, Carmen López Santos

En el proyecto PLASMATER abordamos el desarrollo de nuevos procesos basados en plasmas para controlar la nanoestructura, porosidad y morfología superficial de películas del-gadas, con el objetivo de mejorar sus funcionalidades para aplicaciones finales. En las técnicas de deposición de películas delgadas asistida por plasma, las cantidades que definen la deposi-ción, tales como la potencia electromagnética empleada, presión de los gases, etc., definen las propiedades del plasma, que a su vez, y a través de procesos no-lineales y fuertemente acoplados entre sí, produce el crecimiento de la película delgada en un porta-substrato. La complejidad de todos estos procesos ha dado lugar a que existan multitud de relaciones de carácter empírico entre cantidades controlables experimentales y las nanoestructuras crecidas, sin que haya una explicación clara sobre los mecanismos que controlan dicho crecimiento, y la conexión entre ambas. Este conocimiento es esencial para proponer modificaciones en las condiciones de la deposición que permitiesen un mayor control y versatilidad a la hora de sintetizar películas delgadas nanoestructuradas. En PLASMATER nos proponemos desarrollar herramientas para controlar procesos en plasmas y obtener capas nanoestructuradas y sistemas 1D de TiO2 y ZnO soportados en subs-tratos, para mejorar propiedades funcionales tales como foto-actividad o propiedades de mojado, entre otras. Se explorarán tres aspectos relacionados entre sí: i) diagnosis completa de la fase gaseosa (plasma y vaina) y caracterización de la nanoestructura de los materiales depositados, ii) estudio de las funcionalidades de dichos materiales, y iii) el desarrollo de códigos numéricos predictivos, a partir de los cuales se desarrollen nuevos protocolos que permitan un mayor control sobre la nanoestructura del material y, por lo tanto, sobre las funcionalidades. El uso de modelos predictivos tiene una gran relevancia debido a que, hasta nuestro conocimiento, i) será la primera vez en la literatura que se dé una visión completa del proceso de deposición y nanoestructuración de estas películas delgadas basada en fenómenos fundamentales, a partir del valor de las cantidades experimentales de control (potencia electromagnética empleada, presión de los gases, etc.), y ii) se utilizará el modelo para proponer modificaciones en el proceso de deposición que ayuden a controlar los procesos de nanoestructuración de la película y proveer de más flexibilidad y versatilidad a los materiales depositados con vista a mejorar sus funcionalidades. Para desarrollar el proyecto PLASMATER nos proponemos seguir una estrategia mixta simulación/diagnosis experimental del proceso de deposición para desarrollar interactivamente los modelos de crecimiento en múltiples condiciones. Se considerará el estudio de las diferentes escalas espaciales en el problema, desde el propio plasma (escala típica de decenas de centímetros), la vaina del plasma (por debajo de 1 milímetro), y la superficie del material (decenas de nanometros), y se utilizarán herramientas de diagnostico avanzado del plasma y de la película delgada que ayudarán al desarrollo del proyecto. Por último, la investigación también se centrará en encontrar las condiciones experimentales que permitan obtener la mejores propiedades de las capas con vista a optimizar sus aplicaciones tecnológicas e industriales.


Desarrollo de recubrimientos composite de carbono para aplicaciones biomédicas


15-03-2011 / 15-03-2014



Investigador Principal: Juan Carlos Sánchez López
Organismo Financiador: Junta de Andalucía
Código: P10-TEP 06782

Equipo de Investigación: T. Cristina Rojas, Carlos López Cartes, David Abad, Vanda Godinho, Santiago Domínguez, Inmaculada Rosa

El proyecto comprende el desarrollo de recubrimientos basados en carbono desde su síntesis a medida, caracterización, evaluación en tests de desgaste y estudios de biocompatibilidad para su uso en implantes artificiales. El control del tipo de enlace químico del carbono (sp2/sp3) y la composición química, incluyendo metales como (Ag, Ti) u otros elementos (B, N, O), permitirá modular las propiedades mecánicas y tribológicas (dureza, fricción y resistencia al desgaste) con objeto de incrementar su comportamiento final. Para ello se propone el empleo de la técnica de pulverización catódica (del inglés magnetron sputtering) para depositar estos recubrimientos avanzados sobre los materiales usados en los implantes (acero, aleaciones de Ti o polímeros) bajo diferentes condiciones de síntesis. Seguidamente, éstos composites de carbono serán evaluados de forma comparativa en ensayos de fricción y desgaste que simulen las condiciones que estos materiales se encontrarán en la aplicación final. De esta manera será posible establecer una correlación entre el comportamiento observado y las características químicas y estructurales de las capas preparadas bajo diferentes condiciones de síntesis. Finalmente, la biocompatibilidad será estudiada en ensayos de adhesión celular, citotoxicidad y actividad antibacteriana. Este completo conjunto de análisis aportará una excelente perspectiva de las posibilidades de transferencia tecnológica de estos materiales avanzados a la biomedicina.


Láminas delgadas porosas funcionales y nanoestructuras 1D soportadas de óxidos para el desarrollo de microfluídica en lámina delgada, válvulas fotónicas y micro plasmas (POROUSFILMS)


01-01-2011 / 31-12-2013



Investigador Principal: Francisco Yubero Valencia
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: MAT2010-18447

Equipo de Investigación: Agustín R. González-Elipe, Juan Pedro Espinós Manzorro, Alberto Palmero Acebedo, Rafael Alvarez Molina, Juan Carlos González González, Victor J. Rico Gavira, Jorge Gil Rostra, Ana Isabel Borrás Martos, Lola González García, José Cotrino Bautista

En este proyecto se prepararán láminas delgadas de TiO2, ZnO, SiO2 y SnO2 dopado, así como nanostructruras de fibras soportadas de estos óxidos mediante deposition por plasma y por evaporación a ángulo rasante (GLAD). Se controlará la nano- y micro-estructura de las capas y fibras mediante la selección de las condiciones adecuadas de deposición usando GLAD y, en el caso de la deposición mediante plasma, tras ajustar y modelizar el plasma y sus principales parámetros de operación, así como los fenómenos ligados a la vaina del plasma y su influencia en el desarrollo de la nanoestructura de las capas y fibras. El primer objetivo del proyecto es conseguir controlar la porosidad y otras propiedades críticas (ópticas, conductividad eléctrica, comportameinto frente al mojado, etc.) de los materiales sintetizados para propiciar el desarrollo de nuevos métodos de manejo de fluidos (líquidos y gases) a escalas micro y, posiblemente, nanométricas de manera de inventar y desarrollar aplicaciones en los campos de microfuídica y microplasmas. Un objetivo adicional es el procesado de estas estructuras tanto en una aproximación 2D (procesado litográfico) como 3D mediante el uso de técnicas basadas en láser, el apilamiento en multicpas de diferentes estrucuras de capas finas porosas y/o la deposición selectiva de zonas hidrofóbicas de otros materiales tales como polímeros, siliconas, etc. A partir de estas estructuras se desarrollarán dispositivos microfluídicos basados en láminas delgadas porosas de TiO2 y ZnO activadas con luz (válvulas fotónicas). Estos materiales se vuelven superhidrofílicos cuando se iluminan con luz de <390 nm que, usada para iluminar ciertas áreas pequeñas del material (canales, circuitos micrométricos, etc.) usando lámparas adecuadas o un láser, permitirá activar selectivamente esas zonas. El desarrollo de microfiltración controlada por luz es otra nueva aplicación en este campo que debe permitir la difusión/filtración preferente de líquidos polares a través de las zonas iluminadas (válvula abierta). Conseguir una rápida reversión de este proceso (válvula cerrada) is otro reto que se abordará dentro del proyecto. Un objetivo final de carácter exploratorio es el modelado, diseño y desarrollo de mi-croplasmas basados en las estrucutras porosas en forma de capa delgada desarrolladas durante las etapas iniciales del trabajo. Estos prototipos de microplasmas estarán formados por electrodos de capas porosas de SnO2 dopadas permeables a gases y capas aislantes porosas de SiO2 que actuarán como barreras de separación. La evaluación de las caracterísitcas del plasma en estos dispositivos prototipo será una acción addicional que se abordará en el proyecto.


Nuevas técnicas de procesado en cerámica y vidrio respetuosas con el medio ambiente (CERAMGLASS)


1-01-2011 / 31-12-2014



Investigador Principal: Xermán F. de la Fuente Leis
Organismo Financiador: Ministerio de Economía y Competitividad
Código: LIFE11 ENV/ES/560

Equipo de Investigación: ICMS: Agustín R. González-Elipe, Victor J. Rico, Angel Barranco Quero, Juan Pedro Espinós Manzorro, Jorge Gil, Francisco Yubero Valencia

El objetivo general del proyecto CERAMGLASS es disminuir el impacto al medio ambiente durante los tratamientos térmicos en la industria cerámica mediante la aplicación de una tecnología innovadora de horno láser a cerámica plana y vridrio. El proyecto persigue construir una planta piloto basada en la combinación innovadora de un horno continuo y un láser que barra la superficie. El propósito es probar que esta combinación permite una reducción significativa en el consumo energético y la escalabilidad industrial del proceso.
En primer lugar, el proyecto persigue demostrar que es posible producir placas cerámicas robustas de sólo 4 mm de espesor. Esto significaría una reducción del 50% en el espesor, con la consiguiente reducción en el consumo de materias primas. El proyecto persigue también adaptar las composiciones decorativas incorporando el uso de materiales menos agresivos al uso del procesado láser. En concreto, se tratará de adaptar los procesos de decorado “screen printing” a productos de tercer fuego con lustre y efectos metálicos, así como el de tintas decorativas al vidrio plano. La sustitución de productos iniciales tóxicos permitirá una disminución en la generación de CO2 y otras emisiones gaseosas, residuos tóxicos y la reducción de los requerimientos energéticos del proceso.
 


Síntesis mediante plasma CVD de nuevos materiales orgánicos nanoestructurados integrado en dispositivos planares para aplicaciones como sensores fotónicos y de marcaje de seguridad NANOPLASMA


01-01-2011 / 31-12-2013



Investigador Principal: Angel Barranco Quero
Organismo Financiador: Ministerio de Ciencia e Innovación. Programa  FEDER Unión Europea
Código: MAT2010-21228

Equipo de Investigación: Ana Borrás Martos, Agustín R. González-Elipe, Carmen Ruiz, M. Carmen López-Santos

En NANOPLASMA se propone el desarrollo de nuevas técnicas basadas en plasmas para la síntesis y procesado de nuevos materiales funcionales orgánicos. La tecnología de plasma para síntesis de materiales actualmente en uso, como el CVD activado por plasma (PECVD) o los procesos de polimerización por plasma, implica siempre la fragmentación completa de un precursor volátil. En contraste NANOPLASMA persigue la síntesis de una nueva familia de materiales luminiscentes en forma de película delgada o nanocables 1D soportados, mediante el control químico y del proceso de fragmentación en la zona remota de una descarga de plasma. La investigación se centrará en la síntesis de matrices orgánicas con microestructura nanométrica controlada que incorporan moléculas orgánicas luminiscentes (por ejemplo perilenos, rodaminas, ftalocianinas y porfirinas) y nanocables orgánicos 1D a partir del mismo tipo de moléculas. El proyecto también contempla el desarrollo de metodologías basadas en procesos de etching por plasma y ablación láser, para la fabricación de patrones litográficos 2D a partir de las láminas delgadas y las nanoestructuras soportadas. La investigación se contempla con estudios básicos encaminados al desarrollo de procesos de “patterning químico” basados en procesos de funcionalización superficial mediante plasmas y de derivatización química de monocapas autoensambladas. Tanto la metodología sintética mediante plasmas remotos como los procesos de microstructuración son totalmente compatibles con la tecnología optoelectrónica actual y la tecnología microelectrónica. Ambos procesos, por tanto, pueden llevarse a cabo a escala de oblea de silicio (wafer scale) y escalarse a procesos de fabricación industrial efectivos. Estos materiales y procesos se emplearán en la fabricación de dos tipos de dispositivos a escala de prototipo como son: los sensores de gases fotónicos y las microestructuras luminiscentes para aplicaciones de marcado inteligente. Los sensores de gases consistirán en una lámina o estructura luminiscente integrada en un cristal fotónico 1D diseñados de acuerdo a las propiedades ópticas y la longitud de onda de la emisión luminiscente de la capa sensora correspondiente. Los dispositivos de marcado inteligente consistirán en patrones litográficos complejos construidos a partir de láminas o multicapas luminiscentes con funcionalidades específicas e, incluso, respuesta ambiental o sensora no desarrollada por ninguna otra tecnología hasta la fecha.


Sistemas para la Detección de Explosivos en Infraestructuras Públicas


1-09-2010 / 31-10-2011



Investigador Principal: Angel Barranco Quero
Organismo Financiador: Ministerio de Industria (Contrato: ARQUIMEA)
Código: Centro para el Desarrollo Tecnológico Industrial (Programa CENIT)

Equipo de Investigación: Francisco Javier Aparicio, Agustín R. González-Elipe, Ana Isabel Borrás Martos, Juan Pedro Espinós

El objetivo de este proyecto es el desarrollo de láminas delgadas con propiedades ópticas adecuadas como elementos activos en sensores ópticos capaces de responder a la presencia de gases y/o productos volátiles procedentes de la descomposición parcial de explosivos.


Desarrollo de membranas de regeneración ósea guiada modificadas a escala nanométrica (OSTEOMEM)


03-02-2010 / 02-02-2013



Investigador Principal: Agustín R. González-Elipe
Organismo Financiador: Junta de Andalucía
Código: P09-CTS-5189 (Proyecto de Excelencia)

Equipo de Investigación: José Cotrino Bautista, Rafael Alvarez Molina, Carmen López Santos, Jorge Gil Rostra, Antonia Terriza Fernández

OSTEOMEM persigue el desarrollo de membranas de regeneración ósea reabsorbibles y biodegradables de base polimérica para su uso en cirugía oral y maxilofacial para el tratamiento de defectos óseos. Durante la curación de estos, las membranas deben preservar la aparición de tejidos blandos en los mismos propiciando que la regeneración del hueso ocupe el defecto, dejando tras la reabsorción de la membrana una estructura de tejidos análoga a la que existía antes de la intervención quirúrgica. Este efecto se basa fundamentalmente en un mecanismo de barrera con membranas que se degradan en el interior del cuerpo en un periodo de cuatro a seis meses, evitando la segunda cirugía que generalmente se requiere para retirar membranas no biodegradables. Se espera que las membranas desarrolladas en el proyecto permitan alcanzar los resultados clínicos de las membranas de regeneración animal evitando los problemas asociados a su origen.


Nanopartículas funcionalizadas para aplicaciones de hipertermia y evaluación de su ecotoxicidad


03-02-2010 / 02-02-2013



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Junta de Andalucía
Código: P09-FQM-4554

Equipo de Investigación: J. Blasco, M. Hampel, Carlos López, L.M. Lubián, I. Moreno, Miguel Angel Muñoz, David Philippon, T. Cristina Rojas, Inmaculada Rosa, Carlos García-Negrete

En este Proyecto de Excelencia se parte de la experiencia previa del grupo TEP-217 en el desarrollo y caracterización de nanopartículas funcionalizadas potencialmente biocompatibles y se pretende avanzar en cuatro direcciones. a) Continuar con el desarrollo de nanopartículas basadas principalmente en Au, Ag y óxidos magnéticos con distintas funcionalizaciones y microestructura. b) Profundizar en la fisico-química de su interacción con campos electromagnéticos (en un amplio rango de frecuencias desde kHz a GHz) para producir calentamientos localizados. Actualmente se han propuesto distintos mecanismos (corrientes inducidas, histéresis, relajación de momentos magnéticos y movimiento browniano) sin que existan todavía suficientes datos para comprender e interpretar los resultados experimentales. c) Establecer una colaboración multidisciplinar con el grupo RNM-306, especialista en ensayos de ecotoxicidad, que permita mejorar el conocimiento del impacto ambiental de las nanopartículas (principalmente de oro y plata) en los ecosistemas marinos, que son el sumidero final de una buena parte de los nanomateriales producidos en la actualidad. d) Realizar estudios preliminares de la toxicidad de las nanopartículas en función del campo electromagnético aplicado. En cualquier proyecto dedicado a la nanotecnología resulta extremadamente valioso introducir estudios que nos permitan determinar el impacto toxicológico y ambiental de los nuevos materiales que se están desarrollando en la actualidad.

Un objetivo fundamental de este proyecto es la formación de personal investigador a través de la realización de una Tesis Doctoral en el Instituto de Ciencia de Materiales de Sevilla.


Materiales mesoporosos (HA-SBA-15) funcionalizados con una proteína rhBMP-2 con afinidad por colágeno y sus estructuras híbridas con colágeno para ingeniería del tejido óseo


01-01-2010 / 31-12- 2012



Investigador Principal: M. Aránzazu Díaz Cuenca
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: BIO2009-13903-C02-02

Equipo de Investigación: M. Lourdes Ramiro Gutiérrez

Los materiales soporte denominados biomateriales, matrices, armazones, andamiajes tisulares o scaffold son uno de los elementos básicos para la fabricación de nuevos tejidos artificiales. El biomaterial sirve de soporte para las interacciones celulares y para la formación de matriz extracelular (ECM). Entre los distintos tipos de materiales que se emplean naturales o sintéticos, las cerámicas bioactivas con base de sílice en el sistema ternario SiO2-CaO-P2O5 han mostrado excelente propiedades para su aplicación en cirugía ortopédica reparadora y regeneradora. Por otra parte el desarrollo de nuevas rutas de síntesis que combinan la química sol-gel y el autoensamblado de moléculas (polímeros) directoras o formadoras de estructura ofrece grandes posibilidades para la síntesis de de nuevos materiales bioactivos organizados a escala nanométrica con alta superficie y reactividades mejoradas. Trabajo previo de la IP de esta solicitud ha resultado en la síntesis de un nuevo biomaterial nanocomposite (HA-SBA-15) biocompatible constituido por nanopartículas de hidroxiapatito de calcio en asociación con la matriz de sílice mesoestructurada. Además de la biocompatibilidad, la alta superficie y la distribución de poros con un tamaño homogéneo hacen que este material sea un candidato muy interesante para su utilización como matriz para la adsorción de moléculas terapéuticas, medicamentos o factores de crecimiento que requieran su liberación de forma controlada. Las proteínas morfogenéticas de hueso (BMPs) han sido utilizadas ampliamente debido a sus propiedades osteoinductoras. Las proteínas recombinantes BMP-2 y BMP-7 han sido aprobadas por la FDA para su uso en cirugía ortopédica, sin embargo, el uso de estos factores de crecimiento no está muy extendido debido al alto costo de estos tratamientos y al miedo a posibles efectos secundarios como consecuencia de su utilización en altas concentraciones sin un sistema de liberación adecuado. Por otra parte resultados recientes del equipo coordinador de esta solicitud (subproyecto 2) ha producido y patentado una proteína recombinante BMP (rh-BMP-2) con un dominio de unión al colágeno tipo I (CBD). Esta proteína de fusión ha mostrado ventajas respecto a la proteína nativa BMP-2 y su uso combinado con colágeno puede representar una alternativa terapéutica mejor y más segura en la reparación del tejido óseo. En este subproyecto se propone el estudio de nuevas rutas de síntesis para producir un material nano-organizado (HA-SBA-15) con variaciones en los parámetros texturales y las nanopartículas de HA con el objetivo de optimizar las propiedades de adsorción y posterior liberación de la proteína rhBMP-2 con afinidad por colágeno. Un objetivo paralelo será determinar las variables y condiciones experimentales adecuadas para incorporar la proteína rhBMP-2-CBD al material nano-organizado. El estudio analizará la cantidad de biomolécula, la cinética de desorción y su integridad. Una segunda tarea de esta propuesta es la consolidación del material particulado nano-organizado en piezas tridimensionales híbridas de material cerámico-colágeno biocompatibles, macroporosas y con una estabilidad mecánica mínima que permita su utilización en los experimentos in vivo que se proponen llevar a cabo como parte de las tareas del Subproyecto 2. Se ensayaran métodos para obtener piezas tridimensionales que conserven sus características nanoestructuradas. Se abordará la integración del material sin funcionalizar y funcionalizado con rhBMP-2-CBD.


Materiales poliméricos y nanocomposites híbridos en forma de lámina delgada para aplicaciones fotónicas y fotovoltaicas (NANOPHOTON)


01-01-2010 / 02-02-2013



Investigador Principal: Angel Barranco Quero
Organismo Financiador: Junta de Andalucía
Código: P09-TEP-5283 (Proyecto de Excelencia)

Equipo de Investigación: Ana Borrás, Fabián Frutos, Lola González-García, Said Hamad, S. Lago, Alberto Palmero, Carmen Ruiz-Herrero, Juan R. Sánchez-Valencia, Johan Toudert

El proyecto NANOPHOTON persigue el desarrollo de una nueva familia de materiales, estructuras y prototipos de dispositivos con aplicación en campos tales como el aprovecha-miento de energía solar, el análisis medioambiental y la tecnología espacial. El punto de parti-da del proyecto es la investigación en nuevos materiales ópticamente activos en forma de película delgada nanométrica de carácter polimérico e híbrido. Estas láminas delgadas activas se procesarán e integrarán usando diferentes técnicas para formar estructuras ópticas de uso como sensores fotónicos ambientales, filtros fotónicos insensibles al ángulo de incidencia para comunicaciones en satélites y celdas fotovoltaicas. Un aspecto muy interesante del proyecto es su completa compatibilidad con los métodos sintéticos de uso común en tecnología microelectrónica y optoelectrónica siendo fácilmente transferibles a la industria. NANOPHOTON integra desde estudios fundamentales de simulación molecular a procesos de fabricación de estructuras nanométricas con actividad fotónica pasando por la fabricación de estructuras y prototipos para llegar a test de validación de prototipos en condiciones reales.


Papel de los aditivos en los sistemas composites de hidruros metálicos reactivos para almacenamiento de hidrógeno


01/01/2010 - 31/12/2012



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Ministerio de Educación y Ciencia
Código: CTQ2009-13440

Equipo de Investigación: Carlos López, Cristina Rojas Ruiz, Gisela Arzac, Dirk Hufschmidt, Raimondo Ceccini, Emilie Deprez

Dada la problemática actual por el agotamiento a corto-medio plazo de los combusti-bles fósiles y los cambios climáticos causados por el efecto invernadero, se hace necesaria la reconsideración de una política energética global. El hidrógeno como vector de transporte y almacenamiento de energía es un candidato muy atractivo por tratarse de una alternativa viable y limpia. En el presente proyecto se propone el estudio de los llamados sistemas composites de hidruros reactivos (RHC) para almacenamiento de hidrógeno. Estos sistemas se basan en acoplar un hidruro metálico sencillo (i.e. MgH2) con un hidruro complejo (típicamente un compuesto borohidruro, i.e LiBH4) para dar una reacción reversible que produce o consume hidrógeno. El sistema puede así usarse como material para almacenamiento de hidrógeno de acuerdo a la siguiente reacción: MgH2+2LiBH4 ↔ MgB2+LiH+4H2 (11.4 wt% capacidad de almacenamiento de hidrógeno). La reacción mejora el balance de calor, en comparación con el MgH2 puro, al reducir la liberación de calor durante el proceso de carga. Para mejorar los aspectos cinéticos (reducción de las temperaturas y tiempos de operación) se ha propuesto el uso de catalizadores y/o aditivos. El principal objetivo del proyecto es comprender el papel de estos aditivos para mejorar las cinéticas de sorción de hidrógeno. En particular se han seleccionado como aditivos para este estudio los productos comerciales Ti-Isopropoxide (TiO4C12H28), TiO2 y VCl3 . También se prepararan en nuestro laboratorio otros catalizadores como Co3B, Ni3B o RuCo que igualmente se ensayarán. Los sistemas se prepararán y activarán por molienda de alta energía de los dos mate-riales hidruros molidos juntos con ó sin aditivos (5-10 mol%). Los estudios cinéticos se llevarán a cabo a través de medidas de sorción gravimétrica y volumétrica de hidrógeno (desorción o absorción vs. tiempo a T constante) y de la calorimetría de barrido diferencial (DSC). Se llevará también a cabo un estudio exhaustivo de caracterización microestructural y química de los sistemas en las diferentes etapas (tras la molienda, desorbidos y re-absorbidos) con las si-guientes técnicas: Difracción de rayos X (XRD), microscopía electrónica de transmisión (TEM) acoplada al análisis EDX (energía dispersiva de rayos X) y EELS (espectroscopía de pérdida de energía de electrones), espectroscopía de fotoemisión (XPS) y espectroscopía de absorción de rayos X (XAS). El estudio comparativo de las muestras con y sin aditivos y la correlación entre los estudios cinéticos y el análisis microestructural y químico, deben clarificar el mecanismo de la mejora cinética producida por los aditivos. Estos mecanismos están a día de hoy lejos de ser comprendidos. Sobre la base del conocimiento adquirido se espera mejorar de manera significativa estos sistemas en relación a sus aplicaciones para almacenamiento de hidrógeno.


Estudio de Materiales modificados superficialmente mediante Reflexafs SURCOXAFS


01-01-2009 / 31-12-2011



Investigador Principal: Adela Muñoz Páez
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: MAT2008-06652

Equipo de Investigación: Stuart Ansell, Regla Ayala Espinar, Sofía Díaz Moreno, Lola González García, José Manuel Martínez Fernández, Víctor López Flores

La espectroscopia de Absorción de Rayos X en modo reflexión, ReflEXAFS, es una técnica novedosa que proporciona la información característica del EXAFS, estructura del entorno local del elemento absorbente, junto con la obtenida por medidas de reflectometría, tales como rugosidad, espesor de capa o densidad. Todo ello focalizado en la zona próxima a la superficie, proporcionando además la posibilidad de controlar el espesor analizado en función del ángulo de incidencia del haz, en el rango de 20 a 200 Ǻ. Asimismo, y a diferencia de otras espectroscopias superficiales como XPS, permite acceder a capas “enterradas”. Por ello es muy útil para el estudio de materiales con propiedades singulares en su superficie, tales como los modificados superficialmente y los obtenidos por deposición de capas finas. Habiendo desarrollando los protocolos de medida en proyectos previos, se propone la aplicación de la técnica a sistemas reales de dos tipos: aceros modificados superficialmente mediante nitruración y materiales formados por capas finas mixtas con propiedades ópticas y magnéticas singulares. Aparte del interés intrínseco de la técnica y de los sistemas objeto de estudio, este proyecto tiene relevancia en el marco del desarrollo de la espectroscopia XAS en relación con la línea española del ESRF, SPLINE, y de la nueva fuente española de radiación sincrotrón ALBA.


Funcionalización superficial de materiales para aplicaciones de alto valor añadido (FUNCOAT)


15-12-2008 / 15-12-2013



Investigador Principal: Agustín R. González-Elipe
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: CSD2008- 00023 (Consolider)

Equipo de Investigación: Fernández Camacho, A., Espinós, J.P., Yubero, F., Cotrino, J., Sánchez López, J.C., Barranco, A., Palmero, A., Rojas, C.

FUNCOAT es un proyecto integrado dentro de la convocatoria CONSOLIDER-INGENIO 2010 que persigue explotar las sinergias existentes entre la comunidad científica española en materiales, teniendo como objetivo general el desarrollo de nuevos métodos y la optimización de procedimientos de funcionalización superficial de materiales para la mejora de sus propiedades. El proyecto integra a 14 centros de investigación diferentes, que cubren desde aspectos básicos y teóricos hasta diversas aplicaciones finales. Esta integración de esfuerzos es crítica para lograr avances sustanciales en este campo, más allá que la mera acumulación de resultados. Los grupos de investigación pertenecen a diversas Universidades, CSIC (organismo que actúa como gestor del proyecto) y centros tecnológicos, y presentan relaciones científicas que, en algunos casos, se remontan hasta hace 15 años. Objetivos científico-técnicos parciales son: la comprensión de los fenómenos fundamentales que rigen la modificación de superficies y crecimiento de capas, el control micro y nanoestructural de superficies y capas delgadas, la optimización de los procesos de crecimiento de las capas, la obtención de superficies modificadas con características multifuncionales con aplicaciones en diversos campos (protección mecánica, óptica, magnetismo, biomateriales, energía, etc) y, finalmente, el desarrollo de nuevos dispositivos y aplicaciones de los materiales funcionales en sectores tecnológicos clave. Otros objetivos horizontales, relacionados con los anteriores, son la formación de investigadores en técnicas y métodos de funcionalización y el desarrollo de una transferencia tecnológica eficaz a los sectores productivos. Sectores estratégicos clave en los que las actividades de FUNCOAT inciden con mayor impacto son la metalurgia, vidrio, plásticos, sensores, salud y energía. El proyecto se estructura en torno a los ejes de actividad siguientes que deben permitir la mejor coordinación de los esfuerzos y la integración de las distintas actividades de los grupos. A) Fenómenos básicos de superficies, intercaras y láminas delgadas, B) Nuevos procesos para el control de la micro- y nano- estructura superficiales, C) Recubrimientos mecánicos y metalúrgicos para protección superficial, D) Funcionalización química de superficies y aplicaciones biomédicas, E) Recubrimientos para aplicaciones ópticas y control eficiente de captación energía solar, F) Nuevos fenómenos magnéticos en superficies e interfases.


Desarrollo y diseminación de nuevas técnicas de caracterización nanomecánica y standars


01-09-2008 / 31-08-2011



Investigador Principal: Asunción Fernández Camacho
Organismo Financiador: Unión Europea
Código: NMP3-CA-2008-218659

Equipo de Investigación: Godinho, V., Philippon, D.

El proyecto se dedica al desarrollo, mejora, y standarización de las técnicas de caracterización, los métodos y los equipos en los ensayos nano-mecánicos. Las actividades a nivel Europeo, coordinadas por un centro virtual, mejorarán la metrología de nanoindentación actual y permitirán un conocimiento más profundo de la relación estructura-propiedades en la nano-escala. Estos métodos son una herramienta única para caracterizar el comportamiento mecánico en la nanoescala de nanocomposites, nanocapas e interfases. Este trabajo también producirá una base sólida para definer y preparer nuevos standards que soporten la metodología de caracterización de los nanomateriales. Las etapas incluyen el desarrollo de los métodos clásicos de nanoindentación dinámica y su aplicación a campos nuevos como el rayado y las medidas de desgaste y la aplicación de nano-indentadores modificados. También se trabajará en la determinación uniforme de los parámetros instrumentals y en la definición de standards par alas nuevas aplicaciones. El centro virtual diseminará la información sobre la base de una nueva "base de datos para la caracterización Nano-mecánica". Esto se conseguirá a través de los trabajos de "round robin" entre los socios é incluirá igualmente datos de de otras fuentes de investigación y la búsqueda bibliográfica.


Plasmas de nitrógeno para funcionalizacion superficial de materiales (PLASNITRO)


01-02-2008 / 31-01- 2011



Investigador Principal: José Cotrino Bautista
Organismo Financiador: Junta de Andalucía
Código: P07-FQM-03298 (Proyecto de Excelencia)

Equipo de Investigación: Agustín R. González-Elipe, Francisco Yubero Valencia

En el proyecto PlasNitro se aborda la caracterización de plasmas de nitrógeno en di-versas aplicaciones tecnológicas relacionadas con técnicas de deposición y funcionalización de materiales, reformado y procesos de esterilización que involucran a la Tecnología de Plasma. Se pondrán a punto diferentes procedimientos para medir propiedades de los plasmas, usados en dopado, deposición, funcionalización y modificación de materiales, que contienen nitrógeno usando técnicas de diagnosis basadas en la detección de especies de nitrógeno. El nitrógeno es hoy día un componente usual, sólo o en mezclas con otros gases, en muchos procesos usados en tecnología de plasma. Su caracterización experimental y/o teórica permitirá obtener propiedades fundamentales del plasma (densidad electrónica, temperatura electrónica, temperatura del gas, especies reactivas, etc.) y conocer la contribución a las reacciones homogéneas (en fase plasma) y heterogéneas (interacción plasma-superficie) de los componentes procedentes del nitrógeno. En el proyecto se elaborarán códigos numéricos para obtener la función de distribución electrónica en el plasma. Para este fin será necesaria previamente la evaluación de la distribución vibracional del nitrógeno. Este paso implica tener en cuenta múltiples procesos vibracionales-vibracionales, vibracionales-traslacionales y vibracionales-rotacionales. A partir de la función de distribución electrónica se podrán construir modelos de fluido del plasma en los que intervienen las especies más importantes. Los cálculos teóricos se complementarán con medidas experimentales usando sonda electrostática de Langmuir, que permitirán medir la función de distribución electrónica, así como densidad y temperatura de los electrones. Mediante un analizador de gases residuales se controlará la presión parcial de nitrógeno en cada aplicación y los componentes neutros del plasma. Los modelos cinéticos del plasma de nitrógeno permitirá en muchos casos la interpretación de medidas en el plasma alejado del equilibrio termodinámico y las técnicas de escalado dinámico y simulación Monte Carlo permitirán el control de la nano/microestructura de los materiales depositados/modificados. Se tendrán, de esta forma, técnicas que permitirán controlar y mejorar los procedimientos de trabajo y las propiedades deseadas en los materiales.


Recubrimientos nanoestructurados multifuncionales para aplicaciones mecánicas y tribológicas (NANOMETRIB)


01-10-2007 / 30-09-2011



Investigador Principal: Juan Carlos Sánchez López
Organismo Financiador: Ministerio de Ciencia e Innovación
Código: MAT2007-66881-C02-01

Equipo de Investigación: Asunción Fernández Camacho, Cristina Fernández, Miguel Angel Muñoz-Márquez, Said El Mrabet, Vanda Godinho, M. David Abad

En el campo de las aplicaciones mecánicas y tribológicas, las investigaciones se dirigen al desarrollo de nuevos sistemas que consigan aumentar la eficiencia de operaciones industriales, equipos o herramientas mediante el incremento de la dureza, la reducción de la fricción y la velocidad del desgaste de los materiales en contacto o la resistencia a la oxidación. Estas mejoras suponen un ingente ahorro económico y energético al alargar la vida media de los materiales sin necesidad de su reparación o cambio, como también, una reducción del empleo de emulsiones lubricantes con aceites o grasas. Este proyecto se propone el desarrollo de nuevos recubrimientos nanoestructurados multifuncionales por la técnica de PVD-Magnetron Sputtering para aplicaciones mecánicas y tribológicas en los que se alcance un equilibrado compromiso entre todas las propiedades mencionadas de fricción, dureza, estabilidad térmica. La combinación de múltiples funciones en un mismo material dota de un extraordinario valor añadido al sistema. Para lograr este objetivo general se van a preparar recubrimientos caracterizados donde el tamaño y distribución de las fases componentes, la composición química y su microestructura estén confinados en el rango nanométrico. Los sistemas elegidos comprenden cristales de materiales duros (nitruros, carburos o boruros de metales de transición: Cr, Ti, W) que pueden estar rodeados de una segunda fase que actúe como lubricante a base de C o dicalcogenuros de W) y dopados con ciertos metales para incrementar su resistencia térmica (V ó Nb). En todos los casos, el proyecto comprende su síntesis, caracterización estructural y química, así como su validación práctica en ensayos mecánicos y tribológicos. El estudio de la relación existente entre la microestructura y las propiedades medidas será un objetivo esencial puesto que permitirá una mayor comprensión de los mecanismos de actuación, y por ende, la optimización de tales sistemas nanoestructurados para su mejor aprovechamiento tecnológico.




2025


Materiales Nanoestructurados y Microestructura

On the characteristics of helium filled nano-pores in amorphous silicon thin films

Lacroix, B; Fernández, A; Pyper, NC; Thom, AJW; Whelan, CT
Applied Surface Science, 683 (2025) 161772

A joint theory-experimental study is presented of irregularly shaped nano-pores in amorphous silicon. STEM- ELLS spectra were measured for each pore. The observed helium 1 s 2- 1 s 2 p( 1 P ) excitation energies were found to be shifted from that of a free atom. The relation between the helium density in the pore and these energy shifts is explored and shown to be completely consistent with earlier studies of helium in its bulk condensed phases as well as encapsulated as bubbles in solid silicon. The density, pressure and depth of the pores, all key properties for applications, were determined. An alternative and novel method for determining the depth of the pores more accurately is presented.


Febrero, 2025 | DOI: 10.1016/j.apsusc.2024.161772



2024


Tribología y Protección de Superficies

Microstructural and mechanical properties of TiN/CrN and TiSiN/CrN multilayer coatings deposited in an industrial-scale HiPIMS system: Effect of the Si incorporation

Sala, N; De Figueiredo, MR; Franz, R; Kainz, C; Sánchez-López, JC; Rojas, TC; De los Reyes, DF; Colominas, C; Abad, MD
Surface & Coatings, Technology, 494 (2024) 131461

Surface engineering through the deposition of advanced coatings, particularly multilayer coatings has gained significant interest for enhancing the performance of coated parts. The incorporation of Si into TiN coatings has shown promise for improving hardness, oxidation resistance, and thermal stability, while high-power impulse magnetron sputtering (HiPIMS) has emerged as a technique to deposit coatings with exceptional properties. However, TiN/CrN and TiSiN/CrN coatings deposited by HiPIMS remain relatively unexplored. In this study, different TiN/CrN and TiSiN/CrN multilayer coatings with different bilayer periods from 5 to 85 nm were deposited using an industrial-scale HiPIMS reactor, and their microstructure and mechanical properties were investigated using advanced characterization techniques. Results revealed successful deposition of smooth and compact coatings with controlled bilayer periods. X-ray diffraction analysis showed separate crystalline phases for coatings with high bilayer periods, while those with smaller bilayer periods exhibited peak-overlapping and superlattice overtones, especially for the TiN/CrN coatings. Epitaxial grain growth was confirmed by highresolution transmission electron microscopy (HRTEM). HRTEM and electron energy-loss spectroscopy measurements confirmed Si incorporation into the TiN crystal lattice of TiSiN/CrN coatings reducing the crystallinity, especially for coatings with smaller bilayer periods. Nanoindentation tests revealed that coatings with a bilayer period of 15-20 nm displayed the highest hardness values regardless of the composition. The mechanical properties of the TiSiN/CrN coatings showed no improvement over those of the TiN/CrN coatings, attributed to the Si induced amorphization of the Ti(Si)N phase and the absence of SiNx phase segregation within the TiN nanocrystals in these coatings. These findings provide valuable insights into the microstructure and mechanical properties of TiN/CrN and TiSiN/CrN multilayer coatings deposited by HiPIMS in an industrial scale reactor, paving the way for their application in various industrial sectors.


Octubre, 2024 | DOI: 10.1016/j.surfcoat.2024.131461

Nanotecnología en Superficies y Plasma

Nucleation and growth of plasma sputtered silver nanoparticles under acoustic wave activation

Reichel, H; García-Valenzuela, A; Espino-Román, JA; Gil-Rostra, J; Regodón, GF; Rico-Gavira, V; Borrás, A; Gómez-Ramírez, A; Palmero, A; González-Elipe, AR; Oliva-Ramírez, M
Applied Surface Science, 669 (2024) 160566

Early results on the plasma deposition of dielectric thin films on acoustic wave (AW) activated substrates revealed a densification pattern arisen from the focusing of plasma ions and their impact on specific areas of the piezoelectric substrate. Herein, we extend this methodology to tailor the plasma deposition of metals onto AW-activated LiNbO3 piezoelectric substrates. Our investigation reveals the tracking of the initial stages of nanoparticle (NP) formation and growth during the submonolayer deposition of silver. We elucidate the specific role of AW activation in reducing particle size, enhancing particle circularity, and retarding NP agglomeration and account for the physical phenomena making these processes differ from those occurring on non-activated substrates. We provide a comparative analysis of the results obtained under two representative plasma conditions: diode DC sputtering and magnetron sputtering. In the latter case, the AW activation gives rise to a 2D pattern of domains with different amounts of silver and a distinct size and circularity for the silver NPs. This difference was attributed to the specific characteristics of the plasma sheath formed onto the substrate in each case. The possibilities of tuning the plasmon resonance absorption of silver NPs by AW activation of the sputtering deposition process are discussed.


Octubre, 2024 | DOI: 10.1016/j.apsusc.2024.160566

Nanotecnología en Superficies y Plasma

Hard X-ray Photoelectron Spectroscopy Probing Fe Segregation during the Oxygen Evolution Reaction

Longo, F; Loreda-Jurado, PJ; Gil-Rostra, J; Gonzalez-Elipe, AR; Yubero, F; Thoma, SLJ; Neels, A; Borgschulte, A
ACS Applied Materials & Interfaces, 16 (2024) 59516-59527

NiFe electrocatalysts are among the most active phases for water splitting with regard to the alkaline oxygen evolution reaction (OER). The interplay between Ni and Fe, both at the surface and in the subsurface of the catalyst, is crucial to understanding such outstanding properties and remains a subject of debate. Various phenomena, ranging from the formation of oxides/(oxy)hydroxides to the associated segregation of certain species, occur during the electrochemical reactions and add another dimension of complexity that hinders the rational design of electrodes for water splitting. In this work, we have developed the procedure for the quantification of chemical depth profiling by XPS/HAXPES measurements and applied it to two NiFe electrodes with different porosities. The main outcome of this study is related to the surface reconstruction of the electrodes during the OER, followed at two different depths by means of X-ray photoelectron spectroscopy. We find that Fe initially segregates at the surface when exposed to ambient conditions, resulting in the formation of an inactive FeOx phase. In addition, the porosity of the catalyst plays a significant role in the segregation process and thus in the performance of the electrode. In particular, the higher porosity of the nanostructured sample is responsible for a more pronounced diffusion of Fe from the subsurface to the surface with a more effective suppression of the activity of the Ni1–xFexOOH phase. These results highlight the importance of the fact that the chemical state of the surface of a multielement system is a snapshot in time, dependent on both external parameters, such as the applied potential and the adjacent electrolyte, and the underlying bulk properties accessible with HAXPES.


Octubre, 2024 | DOI: 10.1021/acsami.4c11902

Nanotecnología en Superficies y Plasma

Tailoring of Self-Healable Polydimethylsiloxane Films for Mechanical Energy Harvesting

Ghosh, K; Morgan, A; García-Casas, X; Kar-Narayan, S
ACS Applied Energy Materials, 7 (2024) 8185-8195

Triboelectric nanogenerators (TENGs) have emerged as potential energy sources, as they are capable of harvesting energy from low-frequency mechanical actions such as biological movements, moving parts of machines, mild wind, rain droplets, and others. However, periodic mechanical motion can have a detrimental effect on the triboelectric materials that constitute a TENG device. This study introduces a self-healable triboelectric layer consisting of an Ecoflex-coated self-healable polydimethylsiloxane (SH-PDMS) polymer that can autonomously repair mechanical injury at room temperature and regain its functionality. Different compositions of bis(3-aminopropyl)-terminated PDMS and 1,3,5-triformylbenzene were used to synthesize SH-PDMS films to determine the optimum healing time. The SH-PDMS films contain reversible imine bonds that break when the material is damaged and are subsequently restored by an autonomous healing process. However, the inherent stickiness of the SH-PDMS surface itself renders the material unsuitable for application in TENGs despite its attractive self-healing capability. We show that spin-coating a thin layer (approximate to 32 mu m) of Ecoflex on top of the SH-PDMS eliminates the stickiness issue while retaining the functionality of a triboelectric material. TENGs based on Ecoflex/SH-PDMS and nylon 6 films show excellent output and fatigue performance. Even after incisions were introduced at several locations in the Ecoflex/SH-PDMS film, the TENG spontaneously attained its original output performance after a period of 24 h of healing. This study presents a viable approach to enhancing the longevity of TENGs to harvest energy from continuous mechanical actions, paving the way for durable, self-healable mechanical energy harvesters.


Septiembre, 2024 | DOI: 10.1021/acsaem.4c01275

Nanotecnología en Superficies y Plasma

Efficient tuning of the selectivity of Cu-based interface for electrocatalytic CO2 reduction by ligand modification

Yan, Y; Li, TX; Oliva-Ramirez, M; Zhao, YG; Wang, S; Chen, X; Wang, D; Schaaf, P; Wang, XY, Guo, GS
Materials Today Energy, 44 (2024) 101620

The development of efficient strategies to tune the CO2RR selectivity of Cu-based catalytic interfaces, especially on specific domains, such as Cu (200) facets with high activity toward competitive hydrogenation evolution reaction (HER), remains a challenging task. In this work, Cu-based catalytic layers with thiocyanate (-SCN), cyanide (-CN), or ethylenediamine (-NH2R) coordination linkages are prepared on Cu nanocolumns arrays (Cu NCAs) with predominant (200) exposed facets. The coordination of these ligands induces more Cu+ species and inhibits the adsorption of H & lowast; on the Cu (200) facet, leading to enhanced CO2RR performance and substantially suppressing the competitive HER. The faradaic efficiency (FE) of Cu-SCN, Cu-CN, and Cu-NH2R NWAs for producing HCOOH, C2H4, and C1 mixture products (HCOOH and CO) reach to 66.5%, 21.1%, and 57.1%, respectively. In situ spectroscopic studies reveal Cu-SCN, Cu-CN, and Cu-NH2R exhibit more reasonable adsorption energy toward & lowast;OCHO, *CO, and *COOH intermediates, promoting the HCOOH, C2H4, and C1 mixture generation, respectively. This study might provide a new perspective for the development of high-performance Cu-based CO2RR catalytic electrodes based on the combination of various commercial free-standing Cu substrates and organic/inorganic ligands. (c) 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.


Agosto, 2024 | DOI: 10.1016/j.mtener.2024.101620

Reactividad de Sólidos - Tribología y Protección de Superficies

BN nanosheets reinforced zirconia composites: An in-depth microstructural and mechanical study

Muñoz-Ferreiro, C; Reveron, H; Rojas, TC; Reyes, DF; Cottrino, S; Moreno, P; Prada-Rodrigo, J; Morales-Rodriguez, A; Chevalier, J; Gallardo-López, A; Poyacto, R
Journal of the European Ceramic Society, 44(10) (2024) 5846-5860

This paper deals with the effect of hydroxylated boron nitride nanosheets (BNNS) incorporation on the microstructural and mechanical features of zirconia ceramics. Few-layered BNNS were synthesized via a simple hydroxide-assisted planetary ball milling exfoliation technique. 3 mol% yttria tetragonal zirconia polycrystal (3Y-TZP) with 2.5 vol% BNNS powders were prepared by an environmentally friendly process in water, and spark-plasma sintered at three temperatures to explore the in-situ reduction of the functionalized BNNS. An exhaustive study by (S)TEM techniques was performed to elucidate the influence of the sintering temperature on the matrix and the 3Y-TZP/BNNS interfaces, revealing that BNNS were homogeneously distributed throughout the matrix with an abrupt transition at 3Y-TZP/BNNS interfaces. BNNS effectively hindered slow crack growth, thus increasing the composite's crack growth resistance by about 30 %. A 1 MPa·m1/2 rising R-curve was also induced by crack bridging.


Agosto, 2024 | DOI: 10.1016/j.jeurceramsoc.2024.02.002

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Conformal TiO2 Aerogel-Like Films by Plasma Deposition: from Omniphobic Antireflective Coatings to Perovskite Solar Cell Photoelectrodesh

Obrero, JM; Contreras-Bernal, L; Rebollo, FJA; Rojas, TC; Ferrer, FJ; Orozco, N; Saghi, Z; Czemak, T; Pedrosa, JM; López-Santos, C; Ostrikov, KK; Borras, A; Sánchez-Valencia, JR; Barranco, A
ACS Applied Materials & Interfaces, 16 (2024) 39746-397600

The ability to control the porosity of thin oxide films is a key factor determining their properties. Despite the abundance of dry processes for synthesizing oxide porous layers, a high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultraporous titanium dioxide thin films at room or mild temperatures (T <= 120 degrees C) by a sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85% that are comparable to those of advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures, presenting a distribution of anatase clusters embedded in the sponge-like open porous structure. Surprisingly, the porous structure remains after annealing the films at 450 degrees C in air, which increases the fraction of embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive, becoming superhydrophilic when subjected to ultraviolet light irradiation. The supported, percolated, and nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel-like film thickness, which reaches efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and applicable to ultrahigh porous conformal oxides of different compositions, with potential applications in photonics, optoelectronics, energy storage, and controlled wetting.


Julio, 2024 | DOI: 10.1021/acsami.4c00555

Materiales Nanoestructurados y Microestructura

DC magnetron sputter deposition in pure helium gas: formation of porous films or gas/solid nanocomposite coatings

Ibrahim, S; Fernández, A; Brault, P; Sauldubois, A; Desgardin, P; Caillard, A; Hufschmidt, D; De Haro Jiménez, MC, Sauvage, T; Barthe, MF, Thomann, AL
Vacuum, 224 (2024) 113184

Magnetron sputtering of two materials (Aluminum and Silicon) was performed in He gas and led to the formation of very different porous thin films: a fiberform nanostructure or a gas/solid nanocomposite. The composition of the thin films obtained was analyzed by means of ion beam techniques: Rutherford backscattering and proton elastic backscattering spectroscopies to measure the amount of Al(Si) deposited atoms and that of He atoms inserted inside the films. Microstructural and crystalline properties were analyzed by scanning electron microscopy and X-ray diffraction. Transmission electron microscopy coupled with electron energy loss spectroscopy were used to investigate the presence of empty or He filled pores or even bubbles. Correlating the Al(Si) film properties with the deposition conditions evaluated by SRIM (sputtering process at the target) and by a homemade collision code (species transport to the substrate) gave a better insight into the reason for the formation of such different films. The role of both He ions backscattered at the target and surface mobility during the growth is discussed. Comparison with low kinetic energy He + implantation experiments indicates that similar mechanisms, such as He insertion, diffusion inside the lattice, release or accumulation into pores and bubbles, are certainly taking place.


Junio, 2024 | DOI: 10.1016/j.vacuum.2024.113184

Nanotecnología en Superficies y Plasma

Synergistic Integration of Nanogenerators and Solar Cells: Advanced Hybrid Structures and Applications

Hajra, S; Ali, A; Panda, S; Song, HW; Rajaitha, PM; Dubal, D; Borras, A; In-Na, P; Vittayakorn, N; Vivekananthan, V; Kim, HJ; Divya, S; Oh, TH
Advanced Energy Materials, (2024) 2400025

The rapid growth of global energy consumption and the increasing demand for sustainable and renewable energy sources have urged vast research into harnessing energy from various sources. Among them, the most promising approaches are nanogenerators (NGs) and solar cells (SCs), which independently offer innovative solutions for energy harvesting. This review paper presents a comprehensive analysis of the integration of NGs and SCs, exploring advanced hybrid structures and their diverse applications. First, an overview of the principles and working mechanisms of NGs and SCs is provided for seamless hybrid integrations. Then, various design strategies are discussed, such as piezoelectric and triboelectric NGs with different types of SCs. Finally, a wide range of applications are explored that benefit from the synergistic integration of NGs and SCs, including self-powered electronics, wearable devices, environmental monitoring, and wireless sensor networks. The potential for these hybrid systems is highlighted to address real-world energy needs and contribute to developing sustainable and self-sufficient technologies. In conclusion, this review provides valuable insights into the state-of-the-art developments in NGs and SCs integration, shedding light on advanced hybrid structures and their diverse applications.


Junio, 2024 | DOI: 10.1002/aenm.202400025

Materiales Nanoestructurados y Microestructura

Synergistic Effect of He for the Fabrication of Ne and Ar Gas-Charged Silicon Thin Films as Solid Targets for Spectroscopic Studies

Fernández, A; Godinho, V; Ávila, J; Jiménez de Haro, MC; Hufschmidt, D; López-Viejobueno, J; Almanza-Vergara, GE; Ferrer, FJ; Colaux, JL; Lucas, S; Asensio, MC
Nanomaterials, 14(8) (2024) 727

Sputtering of silicon in a He magnetron discharge (MS) has been reported as a bottom-up procedure to obtain He-charged silicon films (i.e., He nanobubbles encapsulated in a silicon matrix). The incorporation of heavier noble gases is demonstrated in this work with a synergistic effect, producing increased Ne and Ar incorporations when using He–Ne and He–Ar gas mixtures in the MS process. Microstructural and chemical characterizations are reported using ion beam analysis (IBA) and scanning and transmission electron microscopies (SEM and TEM). In addition to gas incorporation, He promotes the formation of larger nanobubbles. In the case of Ne, high-resolution X-ray photoelectron and absorption spectroscopies (XPS and XAS) are reported, with remarkable dependence of the Ne 1s photoemission and the Ne K-edge absorption on the nanobubble’s size and composition. The gas (He, Ne and Ar)-charged thin films are proposed as “solid” targets for the characterization of spectroscopic properties of noble gases in a confined state without the need for cryogenics or high-pressure anvils devices. Also, their use as targets for nuclear reaction studies is foreseen.


Abril, 2024 | DOI: 10.3390/nano14080727

Materiales Nanoestructurados y Microestructura

Long-lasting low fluorinated stainless steel hierarchical surfaces for omniphobic, anti-fouling and anti-icing applications

Montes, L; Rico, V; Nuñez-Galvez, F; Arenas, MA; del Campo, AC; Lopez-Flores, V; Espinós, JP; Borrás, A; González-Elipe, AR; López-Santos, C
Surfaces and Interfaces, 46 (2024) 104167

Stainless steel (SS) alloys are prevalent in many industries, household appliances or other commodities, where a strict control of surface properties is required to tailor their interaction with the environment. In this work we report a new procedure of stainless steel surface processing that provides a multifunctional response including superhydrophobicity, omniphobicity, self-cleaning, anti-fouling and effective anti-icing capacity, while still preserving a corrosion resistance similar to that of this material in compact form. The method consists of a first nanostructuration step followed by a low fluorination. The nanostructured surfaces presented a dual scale roughness of hierarchical character. The liquid free approach developed in this work to get this singular surface nanostructuration entails a first laser treatment of stainless steel flat substrates, followed by the deposition of a nanostructured thin layer of this material by electron beam evaporation in an oblique angle configuration. The resulting hierarchical surfaces were subjected to fluorination by: (i) the plasma-assisted deposition of a thin Teflon-like coating or (ii) the grafting of fluorinated molecules. The self-cleanable, anti-adherent and ice repellent character of the resulting low fluorinated surfaces outperformed the behaviour of classical slippery surfaces obtained by the infusion of high amounts of fluorinated liquids. These hierarchical SS surfaces withstood mild abrasion tests and the effect of water jets. Moreover, the corrosion behaviour of the fluorinated surfaces determined through their potentiodynamic analysis revealed a similar corrosion resistance than the flat SS substrates. Outstandingly, after these corrosion tests, the fluorinated samples obtained by grafting preserved their surface functionalities without significant degradation. The high mechanical and chemical stability of these low fluorinated samples support their usage for a large variety of applications.


Marzo, 2024 | DOI: 10.1016/j.surfin.2024.104167

Nanotecnología en Superficies y Plasma

Growth dynamics of nanocolumnar thin films deposited by magnetron sputtering at oblique angles

Alvarez, R; Garcia-Valenzuela, A; Regodon, G; Ferrer, FJ; Rico, V; Garcia-Martin, JM; Gonzalez-Elipe, AR; Palmero, A
Nanotechnology, 35 (2024) 095705

The morphology of numerous nanocolumnar thin films deposited by the magnetron sputtering technique at oblique geometries and at relatively low temperatures has been analyzed for materials as different as Au, Pt, Ti, Cr, TiO2, Al, HfN, Mo, V, WO3 and W. Despite similar deposition conditions, two characteristic nanostructures have been identified depending on the material: a first one defined by highly tilted and symmetric nanocolumnar structures with a relatively high film density, and a second one characterized by rather vertical and asymmetric nanocolumns, with a much lower film density. With the help of a model, the two characteristic nanostructures have been linked to different growth dynamics and, specifically, to different surface relaxation mechanisms upon the incorporation of gaseous species with kinetic energies above the surface binding energy. Moreover, in the case of Ti, a smooth structural transition between the two types of growths has been found when varying the value of the power used to maintain the plasma discharge. Based on these results, the existence of different surface relaxation mechanisms is proposed, which quantitatively explains numerous experimental results under the same conceptual framework.


Febrero, 2024 | DOI: 10.1088/1361-6528/ad113d

Tribología y Protección de Superficies

Synthesis and Characterization of Multilayered CrAlN/Al2O3 Tandem Coating Using HiPIMS for Solar Selective Applications at High Temperature

Sánchez-Pérez, M; Rojas, TR; Reyes, DF; Ferrer, FJ; Farchado, M; Morales, A; Escobar-Galindo, R; Sánchez-López, JC
ACS Applied Energy Materials, 7 (2024) 438-449

The effect of applying a negative bias during deposition of a previously designed multilayer solar selective absorber coating was studied on two types of substrates (316L stainless steel and Inconel 625). The solar selective coating is composed of different chromium aluminum nitride layers deposited using a combination of radiofrequency (RF), direct current (DC), and high-power impulse magnetron sputtering (HiPIMS) technologies. The chemical composition is varied to generate an infrared reflective/absorber layer (with low Al addition and N vacancies) and two CrAlN intermediate layers with medium and high aluminum content (Al/Cr = 0.6 and 1.2). A top aluminum oxide layer (Al2O3) is deposited as an antireflective layer. In this work, a simultaneous DC-pulsed bias (−100 V, 250 kHz) was applied to the substrates in order to increase the film density. The optical performance, thermal stability, and oxidation resistance was evaluated and compared with the performance obtained with similar unbiased coating and a commercial Pyromark paint reference at 600, 700, and 800 °C. The coating remained stable after 200 h of annealing at 600 °C, with solar absorptance (α) values of 93% and 92% for samples deposited on stainless steel and Inconel, respectively, and a thermal emittance ε25°C of 18%. The introduction of additional ion bombardment during film growth through bias assistance resulted in increased durability, thermal stability, and working temperature limits compared with unbiased coatings. The solar-to-mechanical energy conversion efficiency at 800 °C was found to be up to 2 times higher than Pyromark at C = 100 and comparable at C = 1000.


Febrero, 2024 | DOI: 10.1021/acsaem.3c02310

Nanotecnología en Superficies y Plasma

Harnessing a Vibroacoustic Mode for Enabling Smart Functions on Surface Acoustic Wave Devices - Application to Icing Monitoring and Deicing

Karimzadeh, A; Weissker, U; del Moral, J; Winkler, A; Borrás, A; González-Elipe, AR; Jacob, S
Advanced Materials Technologies, (2024) 2301749

Microacoustic wave devices are essential components in the radio frequency (RF) electronics and microelectromechanical systems (MEMS) industry with increasing impact in various sensing and actuation applications. Reliable and smart operation of acoustic wave devices at low costs will cause a crucial advancement. Herein, this study presents the enablement of temperature and mechanical sensing capabilities in a Rayleigh-mode standing surface acoustic wave (sSAW) chip device by harnessing an acoustic shear-thickness dominant wave (SD) using the same set of electrodes. Most importantly, this mode is excited by switching the polarity of the sSAW transducer electrodes by simple electronics, allowing for direct and inexpensive compatibility with an existing setup. The method in the emergent topic of surface de-icing is validated by continuously monitoring temperature and liquid–solid water phase changes using the SD mode, and on-demand Rayleigh-wave deicing with a negligible energy cost. The flexibility for adapting the system to different scenarios, and loads and the potential for scalability opens the path to impact in lab-on-a-chip, internet of things (IoT) technology, and sectors requiring autonomous acoustic wave actuators.


Febrero, 2024 | DOI: 10.1002/admt.202301749

Materiales para Bioingeniería y Regeneración Tisular

New Nano-Crystalline Hydroxyapatite-Polycarboxy/Sulfo Betaine Hybrid Materials: Synthesis and Characterization

Díaz-Cuenca, A; Sezanova, K; Gergulova, R; Rabadjieva, D; Ruseva, K
Molecules, 29(5) (2024) 930

Hybrid materials based on calcium phosphates and synthetic polymers can potentially be used for caries protection due to their similarity to hard tissues in terms of composition, structure and a number of properties. This study is focused on the biomimetic synthesis of hybrid materials consisting of hydroxiapatite and the zwitterionic polymers polysulfobetaine (PSB) and polycarboxybetaine (PCB) using controlled media conditions with a constant pH of 8.0–8.2 and Ca/P = 1.67. The results show that pH control is a dominant factor in the crystal phase formation, so nano-crystalline hydroxyapatite with a Ca/P ratio of 1.63–1.71 was observed as the mineral phase in all the materials prepared. The final polymer content measured for the synthesized hybrid materials was 48–52%. The polymer type affects the final microstructure, and the mineral particle size is thinner and smaller in the synthesis performed using PCB than using PSB. The final intermolecular interaction of the nano-crystallized hydroxyapatite was demonstrated to be stronger with PCB than with PSB as shown by our IR and Raman spectroscopy analyses. The higher remineralization potential of the PCB-containing synthesized material was demonstrated by in vitro testing using artificial saliva.


Febrero, 2024 | DOI: 10.3390/molecules29050930

Nanotecnología en Superficies y Plasma

Towards efficient strain engineering of 2D materials: A four-points bending approach for compressive strain

Li, H; Carrascoso, F; Borrás, A; Moreno, GP; Aparicio, FJ; Barranco, A; Gómez, AC
Nano Research, 17 (2024) 5317-5325

Strain engineering, as a powerful strategy to tune the optical and electrical properties of two-dimensional (2D) materials by deforming their crystal lattice, has attracted significant interest in recent years. 2D materials can sustain ultra-high strains, even up to 10%, due to the lack of dangling bonds on their surface, making them ideal brittle solids. This remarkable mechanical resilience, together with a strong strain-tunable band structure, endows 2D materials with a broad optical and electrical response upon strain. However, strain engineering based on 2D materials is restricted by their nanoscale and strain quantification troubles. In this study, we have modified a homebuilt three-points bending apparatus to transform it into a four-points bending apparatus that allows for the application of both compressive and tensile strains on 2D materials. This approach allows for the efficient and reproducible construction of a strain system and minimizes the buckling effect caused by the van der Waals interaction by adamantane encapsulation strategy. Our results demonstrate the feasibility of introducing compressive strain on 2D materials and the potential for tuning their optical and physical properties through this approach.


Enero, 2024 | DOI: 10.1007/s12274-023-6402-7

Nanotecnología en Superficies y Plasma

Green hydrogen production using doped Fe2O3 foams

Damizia, M; Lloreda-Jurado, PJ; De Filippis, P; de Caprariis, B; Chicardi, E; Sepúlveda, R
International Journal of Hydrogen Energy, 51 (2024) 834-845

 

Hydrogen is the ideal energy vector to reduce our fossil-fuels dependency and diminish the climate change consequence. However, current production is still methane based. It is possible to produce hydrogen using bioethanol from the alcoholic fermentation of organic waste by chemical looping processes, but unfortunately current redox systems generate hydrogen with significant traces of CO. In the case of proton exchange membrane fuel cells (PEMFC), hydrogen must be highly purified to produce electricity. Here, high porosity inter-connected Fe2O3 foams doped with 2 wt% Al2O3 were manufactured by the freeze-casting method, obtaining around 5.1 mmol H2$g?1 sample of highly pure hydrogen (<10 ppm of CO) consuming only 3.42 mmol of ethanol on each redox cycles, with no deactivation. This result shows the possibility of using an abundant and inexpensive raw material as the iron oxide to scale-up the direct pure H2 production and facilitates its use in the automotive sector.


Enero, 2024 | DOI: 10.1016/j.ijhydene.2023.09.008



2023


Nanotecnología en Superficies y Plasma

Spherosilicate-modified epoxy coatings with enhanced icephobic properties for wind turbines applications

Kozera, R; Zietkowska, K; Przybyszewski, B; Boczkowska, A; Sztorch, B; Paku, D; Przekop, RE; Trzcinski, J; Borras, A
Colloids and Surfaces A-Physicochemical and Engineering Aspects, 679 (2023) 132475

Industries around the world use active methods, which include thermal, mechanical and chemical approaches, to reduce icing on aerodynamic surfaces such as wind turbines and aircraft. However, they are often inefficient, costly, and pollute the environment. For years, new coatings with anti-icing properties (so-called icephobic coatings) have been developed to either replace or work in tandem with active systems. In this study, coatings were designed based on an epoxy gelcoat commonly used for wind turbines through chemical modification with spherosilicate derivatives. Di- and tri-functional spherosilicates have both groups that increase the degree of hydro-/icephobicity of composites , groups capable of interacting with epoxy resin and amine hardener. The icephobicity of the surface was determined using ice adhesion. The lowest value of this parameter reached a value of 186 kPa, a 30 % reduction compared to the unmodified coating. In addition, the hydrophobicity of the surface was determined (the highest water contact angle was equal to 103 degrees). A correlation was observed, proven in many works, that as the surface roughness increases, the anti-icing properties deteriorate. For individual modifications, it was also shown that hydrophobicity has a positive effect on ice adhesion. The work also examined the surface zeta potential and determined the durability of the properties after 100 icing/deicing cycles.


Diciembre, 2023 | DOI: 10.1016/j.colsurfa.2023.132475

Nanotecnología en Superficies y Plasma

H2 Production from NH3 in a BaTiO3 Moderated Ferroelectric Packed-Bed Plasma Reactor

Ruiz-Martín, M; Marin-Meana, S; Megías-Sánchez, A; Oliva-Ramírez, M; Cotrino, J; González-Elipe, AR; Gómez-Ramírez, A
Plasma Chemistry and Plasma Processing, 43 (2023) 2093-2110

Plasma decomposition reactions are used for various gas phase chemical processes including the decomposition of ammonia. In this work we show that pure ammonia can be effectively decomposed at atmospheric pressure and ambient temperature using a packed-bed plasma reactor moderated with BaTiO3 ferroelectric pellets without catalyst. The decomposition rate and energy efficiency of this ferroelectric barrier discharge reactor have been monitored as a function of applied voltage (up to a maximum value of 2.5 kV) and flow rate. For each operating condition reaction efficiencies have been correlated with the parameters defining the electrical response of the reactor. It is found that plasma current and volume inside the reactor and hence the energy efficiency of the process and the decomposition rate vary with the applied voltage and the flow of ammonia (a maximum decomposition rate of 14% and an energy efficiency of 150 LH2/kWh has been determined under optimized operation conditions). The role of back reactions (i.e. N2 + 3H2 → 2NH3) in decreasing reactor performance is another key effect affecting the overall efficiency for the ammonia decomposition. The possibilities of ferroelectric barrier discharge reactors to induce the decomposition of ammonia and the importance of keeping the operating temperature below the Curie temperature of the ferroelectric material are highlighted.


Noviembre, 2023 | DOI: 10.1007/s11090-023-10427-7

Fotocatálisis Heterogénea: Aplicaciones - Nanotecnología en Superficies y Plasma

Mechanistic aspects of the reduction of rutile titanium dioxide and its Re-oxidation. Development and destruction of crystallographic shear structures

Bickley, RI; Garside, GR; González-Carreño, T; González-Elipe, AR; Navío, JA
Journal of Solid State Chemistry, 326 (2023) 124174

A model is presented giving the mean dimensions of acicular octadecahedral microcrystallites of a rutile titanium dioxide powder. Reduction at 823 K, in conjunction with ESR, electrical conductivity and controlled re-oxidation has enabled the model to be applied to reduced microcrystallites. At 300 K they contain <0.1% of paramagnetic [Ti3+↑ VO: Ti3+] reduced edge sites and >99.9% of reduced spin-paired [Ti3+↑↓ Ti3+ VO:] sites. These sites are situated on the external crystal faces and on polygonal bulk crystallographic shear (CS) structures inclined to the microcrystal four-fold symmetry axis. CS structures are quantum-sized [Ti4O7VO:] environments which broaden the paramagnetic signals at 78 K. Temperature programmed reduction in H2(g) reveals atomic hydrogen as a precursor to CS structure formation via a lattice template formed on microcrystallite faces. Shear structures are oxidised on their polygonal perimeters at differing rates on the respective microcrystallite faces by anionic vacancy transfer from sub-surface regions.


Octubre, 2023 | DOI: 10.1016/j.jssc.2023.124174

Materiales para Bioingeniería y Regeneración Tisular

Sol–Gel Technologies to Obtain Advanced Bioceramics for Dental Therapeutics

X. Song; J.J. Segura-Egea; A.Díaz-Cuenca
Molecules, 28 (2023) 6967

The aim of this work is to review the application of bioceramic materials in the context of current regenerative dentistry therapies, focusing on the latest advances in the synthesis of advanced materials using the sol–gel methodology. Chemical synthesis, processing and therapeutic possibilities are discussed in a structured way, according to the three main types of ceramic materials used in regenerative dentistry: bioactive glasses and glass ceramics, calcium phosphates and calcium silicates. The morphology and chemical composition of these bioceramics play a crucial role in their biological properties and effectiveness in dental therapeutics. The goal is to understand their chemical, surface, mechanical and biological properties better and develop strategies to control their pore structure, shape, size and compositions. Over the past decades, bioceramic materials have provided excellent results in a wide variety of clinical applications related to hard tissue repair and regeneration. Characteristics, such as their similarity to the chemical composition of the mineral phase of bones and teeth, as well as the possibilities offered by the advances in nanotechnology, are driving the development of new biomimetic materials that are required in regenerative dentistry. The sol–gel technique is a method for producing synthetic bioceramics with high purity and homogeneity at the molecular scale and to control the surfaces, interfaces and porosity at the nanometric scale. The intrinsic nanoporosity of materials produced by the sol–gel technique correlates with the high specific surface area, reactivity and bioactivity of advanced bioceramics.


Octubre, 2023 | DOI: 10.3390/molecules28196967

Materiales Nanoestructurados y Microestructura - Materiales Ópticos Multifuncionales

Understanding the Problem of Hydrogen Storage Using a Demonstration: Coupling a Hydrogen Generator Based on the Hydrolysis of Sodium Borohydride to a Fuel-Cell Kit

Arzac, GM; Calvo, ME; Fernández, A
Journal of Chemical Education. 100 (2023) 4554-4558

In the context of a green global energy paradigm, hydrogen (H-2) is a very promising energy carrier. In fuel cells, hydrogen can be used to generate electricity to drive an electric motor, producing water as its only byproduct. However, to implement hydrogen as an energy vector, developing methods for its production, storage, distribution, and use is essential. Sodium borohydride is a potential hydrogen source capable of releasing H-2 through catalytic hydrolysis. Herein, we present a demonstration that couples a hydrogen generator based on the hydrolysis of sodium borohydride to a commercial fuel-cell kit. The commercial fuel-cell kit operates using the hydrogen generated by an electrolyzer and includes a small fan to prove the successful generation of electricity. The performance of the fuel cell coupled with the borohydride-based reactor is compared to the performance achieved using the hydrogen produced by the electrolyzer. The borohydride-based reactor is designed to power the fan for 300 s and demonstrates efficient and safe hydrogen storage within a small volume of sodium borohydride. This study showcases the hydrogen cycle, the hydrogen storage problem, and the potential of sodium borohydride as a hydrogen storage material in a simple and useful way, contributing to science education and dissemination in the field of energy sustainability.


Octubre, 2023 | DOI: 10.1021/acs.jchemed.3c00590

Nanotecnología en Superficies y Plasma

Plasma assisted dry reforming of methane: Syngas and hydrocarbons formation mechanisms

Navascues, P; Cotrino, J; Gonzalez-Elipe, AR; Gomez-Ramirez, A
Fuel Processing Technology, 248 (2023) 107827

Plasma reactions of CO2 + CH4 mixtures have been proposed as a suitable process for the dry reforming of methane. Without specific catalysts, most studies report the formation of CO and H2 as main reaction products and arise the question whether CHx radicals coming from CH4 may interact with intermediate species formed by electron impact dissociation of CO2, a critical step for the formation of high added value oxygenated compounds. We have addressed this question studying the CO2 + CH4 plasma reaction in a ferroelectric-moderated packed -bed reactor varying the reactants ratio. Analysis of the reaction products by mass spectrometry and the plasma reaction intermediates by optical emission spectroscopy suggest that few direct cross-link interactions exist between intermediate plasma species issued from CH4 or CO2. This preliminary evidence is corroborated by experiments using 13CO2 instead 12CO2 as reactant. The isotope labeling procedure has proved that plasma re-action mechanisms of CO2 and CH4 molecules proceed almost independently, with the formation of small amounts of water and the removal of carbon deposits resulting CH4 plasma decomposition as sole evidences of cross reactions. These results highlight the need of using catalysts to promote specific surface reactions for a better control of the selectivity of the process.


Septiembre, 2023 | DOI: 10.1016/j.fuproc.2023.107827

Nanotecnología en Superficies y Plasma

Exalted dual-scale surface roughening in laser ablated aluminum capped with a transparent thin film: Wetting and anti-icing behavior

Ghemras, I; Montes, L; Lopez-Santos, C; Gonzalez-Elipe, AR; Rico, V
Applied Surface Science, 630 (2023) 157357

Near infrared laser ablation of metals, specifically aluminum, has been systematically applied to generate surface roughness. Very high laser fluences may even lead to a so called "explosive" ablation regime where roughness becomes dramatically enhanced. In the present work we have developed an alternative methodology that, uti-lizing milder laser irradiation conditions (i.e. laser fluences from 0.37 to 0.72 J/cm2), renders aluminum surfaces with a dual-scale roughness character and Sp parameter values twice or even trice the value found in reference samples. This has been possible for aluminum substrates coated with a highly transparent aluminum oxynitride capping layer. The resulting surfaces, consisting of very rough partially oxidized aluminum with negligible amounts of nitrogen species, resulted highly hydrophobic and depicted long icing delay times as required for anti-icing applications. A correlation has been found between the wetting and anti-icing behaviors, the use of a capping layer and the laser irradiation conditions. To account for this exalted roughening phenomenon, we propose that the transparent capping layer confines the laser energy within the aluminum shallow zones, delays the formation of the plasma plume and produces an enhancement in the aluminum ablation, even at relatively low laser fluences.


Septiembre, 2023 | DOI: 10.1016/j.apsusc.2023.157357

Nanotecnología en Superficies y Plasma

Germination and First Stages of Growth in Drought, Salinity, and Cold Stress Conditions of Plasma-Treated Barley Seeds

Perea-Brenes, A; Garcia, JL; Cantos, M; Cotrino, J; Gonzalez-Elipe, AR; Gomez-Ramirez, A; López-Santos, C
ACS Agricultural Science & Technology, 3 (2023) 760-770

Numerous works have demonstrated that cold plasma treatments constitute an effective procedure to accelerate seed germination under nonstress conditions. Evidence also exists about a positive effect of plasmas for germination under environmental stress conditions. For barley seeds, this work studies the influence of cold plasma treatments on the germination rate and initial stages of plant growth in common stress environments, such as drought, salinity, and low-temperature conditions. As a general result, it has been found that the germination rate was higher for plasma-treated than for untreated seeds. Plasma also induced favorable changes in plant and radicle dimensions, which depended on the environment. The obtained results demonstrate that plasma affects the biochemical metabolic chains of seeds and plants, resulting in changes in the concentration of biochemical growing factors, a faster germination, and an initially more robust plant growth, even under stress conditions. These changes in phenotype are accompanied by differences in the concentration of biomarkers such as photosynthetic pigments (chlorophylls a and b and carotenoids), reactive oxygen species, and, particularly, the amino acid proline in the leaves of young plants, with changes that depend on environmental conditions and the application of a plasma treatment. This supports the idea that, rather than an increase in seed water imbibition capacity, there are clear beneficial effects on seedling of plasma treatments.


Septiembre, 2023 | DOI: 10.1021/acsagscitech.3c00121

Nanotecnología en Superficies y Plasma

Paper-based ZnO self-powered sensors and nanogenerators by plasma technology

Garcia-Casas, X; Aparicio, FJ; Budagosky, J; Ghaffarinejad, A; Orozco-Corrales, N; Ostrikov, K; Sánchez-Valencia, JR; Barranco, A; Borras, A
Nano Energy, 114 (2023) 108686

Nanogenerators and self-powered nanosensors have shown the potential to power low-consumption electronics and human-machine interfaces, but their practical implementation requires reliable, environmentally friendly and scalable processes for manufacturing and processing. Furthermore, the emerging flexible and wearable electronics technology demands direct fabrication onto innovative substrates such as paper and plastics typically incompatible with high process temperatures. This article presents a plasma synthesis approach for the fabri-cation of piezoelectric nanogenerators (PENGs) and self-powered sensors on paper substrates. Polycrystalline ZnO nanocolumnar thin films are deposited by plasma-enhanced chemical vapour deposition on common paper supports using a microwave electron cyclotron resonance reactor working at room temperature yielding high growth rates and low structural and interfacial stresses. Applying Kinetic Monte Carlo simulation, we elucidate the basic shadowing mechanism behind the characteristic microstructure and porosity of the ZnO thin films, relating them to an enhanced piezoelectric response to periodic and random inputs. The piezoelectric devices are assembled by embedding the ZnO films in polymethylmethacrylate (PMMA) and using Au thin layers as elec-trodes in two different configurations, namely laterally and vertically contacted devices. We present the response of the laterally connected devices as a force sensor for low-frequency events with different answers to the applied force depending on the impedance circuit, i.e. load values range, a behaviour that is theoretically analyzed. The characterization of the vertical devices in cantilever-like mode reaches instantaneous power densities of 80 nW/ cm2 with a mean power output of 20 nW/cm2. Besides, we analyze their actual-scenario performance by acti-vation with a fan and handwriting. Overall, this work demonstrates the advantages of implementing plasma deposition for piezoelectric films to develop robust, flexible, stretchable, and enhanced-performance nano-generators and self-powered piezoelectric sensors compatible with inexpensive and recyclable supports.


Septiembre, 2023 | DOI: 10.1016/j.nanoen.2023.108686

Materiales Nanoestructurados y Microestructura

Preparation, characterization and activation of Pd catalysts supported on CNx foam for the liquid phase decomposition of formic acid

Arzac, GM; Rojas, TC; Real, C; Fernández, A
International Journal of Hydrogen Energy, 48 (2023) 31899-31613

In this work, we have prepared a series of Pd catalysts on a CNx support for the liquid phase decomposition of formic acid. The structured CNx support was obtained through thermal pyrolysis of melamine foam and the pyrolysis conditions were optimized to achieve high surface area. The resulting support contains high amount of nitrogen with a contribution of pyridinic component. Several Pd catalysts were prepared and under optimized condi-tions, we were able to obtain small (2.7 +/- 0.9) nm Pd particles by using the oxidized support in powdery form. The activity of the optimized catalyst was studied under different con-ditions in the fresh and the used form. The fresh catalyst did not show significant activity. However, we found that the catalyst activated after use. Activation was understood in terms of the variation of surface Pd oxidation states under the effect of formic acid/sodium formate solutions. We found that the best activity is achieved under an optimal proportion of Pd0/PdII surface states according to previous reports. Under the best conditions, the activity of the best catalyst (8.6Pd/CN0.3) was as high as 9245 h-1, attributable to the small particle size, the Pd0/PdII ratio, the amount of pyridinic nitrogen, and the testing conditions, which included the preadsorption of sodium formate


Septiembre, 2023 | DOI: 10.1016/j.ijhydene.2023.04.244

Nanotecnología en Superficies y Plasma - Materiales Ópticos Multifuncionales

Effect of the effective refractive index on the radiative decay rate in nanoparticle thin films

Romero, M; Sánchez-Valencia, JR; Lozano, G; Míguez, H
Nanoscale, 15 (2023) 15279-15287

In this work, we theoretically and experimentally study the influence of the optical environment on the radiative decay rate of rare-earth transitions in luminescent nanoparticles forming a thin film. We use electric dipole sources in finite-difference time-domain simulations to analyze the effect of modifying the effective refractive index of transparent layers made of phosphor nanocrystals doped with rare earth cations, and propose a correction to previously reported analytical models for calculating the radiative decay rate. Our predictions are tested against an experimental realization of such luminescent films, in which we manage to vary the effective refractive index in a gradual and controllable manner. Our model accurately accounts for the measurements attained, allows us to discriminate the radiative and non-radiative contributions to the time-resolved photoluminescence, and provides a way to rationally tune the spontaneous decay rate and hence the photoluminescence quantum yield in an ensemble of luminescent nanoparticles.


Septiembre, 2023 | DOI: 10.1039/d3nr03348a

Nanotecnología en Superficies y Plasma - Materiales Nanoestructurados y Microestructura

Plasmas and acoustic waves to pattern the nanostructure and chemistry of thin films

Rico, V; Regodon, GF; Garcia-Valenzuela, A; Alcaide, AM; Oliva-Ramirez, M; Rojas, TC; Alvarez, R; Palomares, FJ; Palmero, A; Gonzalez-Elipe, AR
Acta Materialia, 255 (2023) 119058

In this work, piezoelectric AWs and plasmas have been brought together during the growth of a thin film as a novel methodology of plasma-assisted thin film structuration. The ensuing effects have been investigated on a model system where SiO2 and SiOx (x<2) thin films have been deposited by magnetron sputtering at oblique angles (MS-OAD) on an electro-acoustically excited LiNbO3 piezoelectric substrate under resonant conditions. The microstructure of the resulting films was 2D patterned and depicted submillimeter size intermingled zones with different optical characteristics, compositions (SiO2 and SiOx) and porosity, from highly porous to dense and compact regions. The 2D nanostructural pattern mimics the AW distribution and has been accounted for by means of a specific simulation model. It is concluded that the morphological and chemical film pattern replicates the distribution of polarization potential on the surface of the AW activated substrate immersed in the plasma. Moreover, we show that the main mechanism responsible for the appearance of domains with different morphology and chemical composition is the focused impingement of Ar+plasma ions on certain regions of the substrate. The general character of this patterning process, the underlying physics and its possibilities to tailor the composition and microstructure of dielectric thin film materials are discussed.


Agosto, 2023 | DOI: 10.1016/j.actamat.2023.119058

Tribología y Protección de Superficies

Ti6Al4V coatings on titanium samples by sputtering techniques: Microstructural and mechanical characterization

Sanchez-Lopez, JC; Rodriguez-Albelo, M; Sanchez-Perez, M; Godinho, V; Lopez-Santos, C; Torres, Y
Journal of Alloys and Compounds, 952 (2023) 170018

Although titanium is widely used as biomaterial, the control of the interface properties between its surface and the surrounding physiological environment (like bone, other tissues or biofluids) results crucial to achieve a successful osseointegration and good biomechanical and functional performance. In this work, commercially pure titanium (Grade IV) discs obtained by conventional powder metallurgy were coated with 1-3 mu m of Ti6Al4V (Grade V) alloy using DC-pulsed or high-power impulse magnetron sputtering (HiPIMS) technique with the aim of improving their biomedical performance. SEM, confocal microscopy, X-ray dif-fraction, nanoindentation and wetting measurements are used to evaluate the bio-interface role of the titanium-coated implants. Conformal Ti6Al4V coatings with controlled nano-roughness can be deposited with enhanced mechanical (H = 5-8 GPa; E = 140-160 GPa) and hydrophobic properties thanks to a dense columnar structure. The increased Ti-O bonding at the interface helps to prevent the corrosion due to the formation of a surface passivation layer. Particularly in the case of the HiPIMS process, the surface mod-ification of titanium implants (chemistry, morphology and structure) appears as an effective strategy for satisfying the biomedical requirements and functionality, with enhanced mechanical properties and na-nostructuration for prevention of bacteria colonization.


Agosto, 2023 | DOI: 10.1016/j.jallcom.2023.170018

Nanotecnología en Superficies y Plasma

Dielectric multilayers for broadband optical rotation enhancement

Pellegrini, G; Mogni, E; Gil-Rostra, J; Yubero, F; Fossati, S; Dostálek, J; Vázquez, RM; Osellame, R; Celebrano, M; Finazzi, M; Biagioni, P
Nuovo Cimento C-Colloquia and Communications in Physics, 46 (2023) 111

We design a simple dielectric multilayer capable of sustaining broadband superchiral surface waves. We show that the platform can produce large optical chirality enhancements in a wavelength range of hundreds of nanometers. We finally demonstrate that these properties result in the enhancement of the optical rotation signal well above two orders of magnitude, thus extending surface-enhanced chiral spectroscopies beyond the traditionally addressed circular dichroism signals.


Julio, 2023 | DOI: 10.1393/ncc/i2023-23111-1

Nanotecnología en Superficies y Plasma

Setting a comprehensive strategy to face the runback icing phenomena

Mora, J et al.
Surface & Coatings Technology, 465 (2023) 129585

The development of anti-icing robust surfaces is a hot topic nowadays and particularly crucial in the aeronautics or wind energy sectors as ice accretion can compromise safety and power generation efficiency. However, the current performance of most anti-icing strategies has been proven insufficient for such demanding applications, particularly in large unprotected zones, which located downstream from thermally protected areas, may undergo secondary icing. Herein, a new testing methodology is proposed to evaluate accretion mechanisms and secondary icing phenomena through, respectively, direct impact and running-wet processes and systematically applied to anti-icing materials including commercial solutions and the latest trends in the state-of-the-art. Five categories of materials (hard, elastomeric, polymeric matrix, SLIPS and superhydrophobic) with up to fifteen formulations have been tested. This Round-Robin approach provides a deeper understanding of anti-icing mechanisms revealing the strengths and weaknesses of each material. The conclusion is that there is no single passive solution for anti-ice protection. Thus, to effectively protect a given real component, different tailored materials fitted for each particular zone of the system are required. For this selection, shape analysis of such a component and the impact characteristics of water droplets under real conditions are needed as schematically illustrated for aeronautic turbines.


Julio, 2023 | DOI: 10.1016/j.surfcoat.2023.129585

Nanotecnología en Superficies y Plasma

Structure and Void Connectivity in Nanocolumnar Thin Films Grown by Magnetron Sputtering at Oblique Angles

Alvarez, R; Regodon, G; Acosta-Rivera, H; Rico, V; Alcala, G; Gonzalez-Elipe, AR; Palmero, A
Coatings, 13 (2023) 991

The morphology and void connectivity of thin films grown by a magnetron sputtering deposition technique at oblique geometries were studied in this paper. A well-tested thin film growth model was employed to assess the features of these layers along with experimental data taken from the literature. A strong variation in the film morphology and pore topology was found as a function of the growth conditions, which have been linked to the different collisional transport of sputtered species in the plasma gas. Four different characteristic film morphologies were identified, such as (i) highly dense and compact, (ii) compact with large, tilted mesopores, (iii) nanocolumns separated by large mesopores, and (iv) vertically aligned sponge-like coalescent nanostructures. Attending to the topology and connectivity of the voids in the film, the nanocolumnar morphology was shown to present a high pore volume and area connected with the outside by means of mesopores, with a diameter above 2 nm, while the sponge-like nanostructure presented a high pore volume and area, as well as a dense network connectivity by means of micropores, with a diameter below 2 nm. The obtained results describe the different features of the porous network in these films and explain the different performances as gas or liquid sensors in electrochromic applications or for infiltration with nanoparticles or large molecules.


Junio, 2023 | DOI: 10.3390/coatings13060991

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Low temperature nucleation of thermochromic VO2 crystal domains in nanocolumnar porous thin films

Alcaide, AM; Regodon, G; Ferrer, FJ; Rico, V; Alvarez, R; Rojas, TC; Gonzalez-Elipe, AR; Palmero, A
Nanotechnology, 34 (2023) 255702

The low temperature formation of monoclinic VO2 crystal domains in nanocolumnar vanadium/oxygen thin films prepared by magnetron sputtering at oblique angles is analyzed. The synthesis procedure involved the deposition of amorphous nanocolumnar VO1.9 thin films at room temperature and its subsequent annealing at temperatures between 250 °C and 330 °C in an oxygen atmosphere. The thermochromic transition of these films was found at a temperature of 47 °C when the annealing temperature was 270 °C and 58 °C when the annealing temperature was 280 °C and 290 °C, presenting a clear drop of the optical transmittance in the infrared region of the spectrum. The significant downshift in the temperature window to obtain VO2 in comparison with compact films and other strategies in literature is explained by the particular morphology of the nanocolumnar structures, which contains numerous defects along with open and embedded porosity.


Junio, 2023 | DOI: 10.1088/1361-6528/acc664

Materiales Nanoestructurados y Microestructura

Microstructural characterization and thermal stability of He charged amorphous silicon films prepared by magnetron sputtering in helium

Fernández, A; Sauvage, T; Diallo, B; Hufschmidt, D; de Haro, MCJ; Montes, O; Martínez-Blanes, JM; Caballero, J; Godinho, V; Ferrer, FJ; Ibrahim, S; Brault, P; Thomann, AL
Materials Chemistry and Physics, 301 (2023) 127674

Sputtering of silicon in a Helium magnetron discharge has been reported as a bottom-up procedure to obtain amorphous Si films containing high amounts of gas-filled nanopores. Here we compare the microstructure and composition of Si-He nanocomposite films deposited by magnetron sputtering (MS) with 4He in DC or RF and 3He in RF operation modes. Electron microscopy (SEM and TEM), X-ray diffraction (XRD) and ion beam analysis (IBA) have been used to analyze the films and to investigate the in-situ and ex-situ thermal evolution. Depending on deposition conditions different in depth compositions, nanopore size and shape distributions, porosity and He content could be obtained. The presence of impurities (i.e. oxygen) has shown to promote He diffusivity reducing He accumulation. The start temperature of He-release varied in the range 473-723 K without films crystallization. Films grown in RF mode reached contents of 32 and 29 at% of 4He and 3He and were respectively stable up to 573 and 723 K both in vacuum and under inert gas flow. In-situ p-EBS (proton Elastic Back Scattering) allowed monitoring the He release accompanied by blistering/delamination effects visualized by SEM. These results show the potentiality of annealing to hold nano-porous structures after liberation of trapped gas.


Junio, 2023 | DOI: 10.1016/j.matchemphys.2023.127674

Tribología y Protección de Superficies

Tribological Response of delta-Bi2O3 Coatings Deposited by RF Magnetron Sputtering

Rodil, SE; Depablos-Rivera, O; Sanchez-Lopez, JC
Lubricants, 11 (2023) 207

Bismuth oxide (Bi2O3) coatings and composite coatings containing this oxide have been studied due to their potential applications in gas sensing, optoelectronics, photocatalysis, and even tribology. Two parametric models based on chemical features have been proposed with the aim of predicting the lubricity response of oxides. However, such models predict contradictory values of the coefficient of friction (COF) for Bi2O3. In this study, we deposited Bi2O3 coatings, via magnetron sputtering, on AISI D2 steel substrates to evaluate the tribological responses of the coatings and determine which parametric model describes them better. Experimentally, only coatings presenting the cubic defective fluorite-like delta-Bi2O3 phase could be evaluated. We performed pin-on-disk tests at room temperature and progressively increasing temperatures up to 300 degrees C using alumina and steel counter-bodies. Low wear and COFs (0.05 to 0.15) indicated that the delta-phase behaves as a lubricious solid, favoring the validity of one of the models. An alternative explanation is proposed for the low COF of the defective fluorite-like structure since it is well known that it contains 25% of anionic vacancies that can be ordered to form low shear-strength planes, similar to the Magneli phases. Two challenges for future potential applications were observed: one was the low adhesion strength to the substrate, and the other was the thermal stability of this phase.


Mayo, 2023 | DOI: 10.3390/lubricants11050207

Nanotecnología en Superficies y Plasma

Strontium/zinc phytate-based self-assembled monolayers on titanium surfaces enhance osteogenesis and antibacterial performance in vitro

Asensio, G; Hernández-Arriaga, AM; Martin-del-Campo, M; Prieto, MA; González-Elipe, AR; Rojo, L; Vázquez-Lasa, B
Applied Surface Science, 620 (2023) 156818

The accumulation of bacteria over implant surfaces is still the first cause of failure, and the development of antimicrobial surfaces constitutes a first line in implant research. Besides, the durability and mechanical performance of implants, in special in the dental area, are mainly determined by their osseointegration capacity into the maxillofacial bone and the appearance of infections. Consequently, implant osseointegration and infection prophylaxis remain as big challenges to attain so a huge investigation is being developed on the production of bioactive surfaces to achieve improvements in these aspects. In this work we propose the functionalization of titanium surfaces (Ti Cp) with self-assembled monolayers (SAMs) of bioactive organophosphate compounds: phytic acid (Ti-PA) and its metallic phytate de- rivatives bearing Sr2+ and/or Zn2+ (Ti-SrPhy, Ti-ZnPhy and Ti-SrPhy/ZnPhy) which exhibited tunable in vitro osteogenic, antimicrobial and antioxidant properties in a previous work. Thus, phytate compounds are chemically anchored onto Ti discs through a simple procedure consisting of a condensation reaction promoted by heat treatment. EDS and XPS spectroscopies confirm the obtaining of the modified surfaces and the topographic properties and wettability analysed by SEM, AFM, profilometry and contact angle measurements, respectively, are explored. Additionally, phytate-SAMs do not release any cytotoxic compound after 14 days and stimulate in vitro adhesion and proliferation of human osteoblast cells after 14 days of culture. The osteogenic ability of the modified surfaces evaluated by the quantification of ALP activity and matrix mineralization degree shows a significant improvement with respect to unmodified surfaces. Furthermore, the antimicrobial activity of phytate-SAMs against Streptococcus mutans cultures is evaluated. The count of viable cells and the quantification of produced biofilm are significantly reduced by all phytate-SAMs groups (p < 0.001). Cell membrane integrity studies by LIVE/DEAD staining and SEM imaging confirm a decreased viability of adhered bacteria when phytate-based surfaces are tested, due to a disruption in the function and permeability of the cell membrane. Therefore, phytate-SAMs exhibit suitable in vitro features suggesting their promising potential as bioactive coatings of dental implants.


Mayo, 2023 | DOI: 10.1016/j.apsusc.2023.156818

Nanotecnología en Superficies y Plasma

Surface Acoustic Waves Equip Materials with Active De-Icing Functionality: Unraveled Glaze Ice De-Icing Mechanisms and Application to Centimeter-Scale Transparent Surfaces

Jacob, S; Pandey, S; Del Moral, J; Karimzadeh, A; Gil-Rostra, J; Gonzalez-Elipe, AR; Borras, A; Winkler, A
Advanced Materials Technologies

Enabling active de-icing functionality on low heat conductive and transparent materials is a requirement for several seminal industries in critical economic sectors. However, developing efficient and environmentally friendly de-icing methods still fails because of compatibility problems with large-scale devices and real-world conditions. In this paper, de-icing several square centimeters covered with thick layers of glaze ice is approached through nanoscale activation by surface acoustic waves (SAWs). De-icing functionality is demonstrated with a self-supported piezoelectric material (LiNbO3) and a piezoelectric film (ZnO) deposited on fused silica, the latter system proving the compatibility of the method with materials of practical relevance. Its applicability to large and transparent substrates is demonstrated by placing the interdigitated electrodes (IDTs) required for activation close to the substrate's edges, leaving most of the surface unaltered. The de-icing mechanism of glaze ice by SAW activation is revealed by simulating the SAW propagation on ice-covered surfaces and by experimental analysis of the ice melting process. This involves a combination of ice mechanical stress activation and heating through the initially formed water/ice front. Possible Joule effects due to ohmic losses in the IDTs have been discarded, monitoring local temperature variations during SAW activation at and out of resonance conditions.


Mayo, 2023 | DOI: 10.1002/admt.202300263

Nanotecnología en Superficies y Plasma

Optical monitoring of detergent pollutants in greywater

Lahoz, F; de Armas-Rillo, S; Hernandez-Rodriguez, C; Gil-Rostra, J; Yubero, F
Optics Express, 31 (2023) 15227-15238

Large amount of wastewater is produced by washing machines and dishwashers, which are used in a daily basis. This domestic wastewater generated in households or office buildings (also called greywater) is drained directly to the drainpipes without differentiation from that with fecal contamination from toilets. Detergents are arguably the pollutants most frequently found in greywater from home appliances. Their concentrations vary in the successive stages in a wash cycle, which could be taken into account in a rational design of home appliances wastewater management. Analytical chemistry procedures are commonly used to determine the pollutant content in wastewater. They require collecting samples and their transport to properly equipped laboratories, which hampers real time wastewater management. In this paper, optofluidic devices based on planar Fabry-Perot microresonators operating in transmission mode in the visible and near infrared spectral ranges have been studied to determine the concentration of five brands of soap dissolved in water. It is found that the spectral positions of the optical resonances redshift when the soap concentration increases in the corresponding solutions. Experimental calibration curves of the optofluidic device were used to determine the soap concentration of wastewater from the successive stages of a washing machine wash cycle either loaded with garments or unloaded. Interestingly, the analysis of the optical sensor indicated that the greywater from the last water discharge of the wash cycle could be reused for gardening or agriculture. The integration of this kind of microfluidic devices into the home appliances design could lead to reduce our hydric environmental impact.


Mayo, 2023 | DOI: 10.1364/OE.466194

Nanotecnología en Superficies y Plasma

Advanced Cellulose-Nanocarbon Composite Films for High-Performance Triboelectric and Piezoelectric Nanogenerators

Gonzalez, J; Ghaffarinejad, A; Ivanov, M; Ferreira, P; Vilarinho, PM; Borras, A; Amorin, H; Wicklein, B
Nanomaterials, 13 (2023) 1206

Natural polymers such as cellulose have interesting tribo- and piezoelectric properties for paper-based energy harvesters, but their low performance in providing sufficient output power is still an impediment to a wider deployment for IoT and other low-power applications. In this study, different types of celluloses were combined with nanosized carbon fillers to investigate their effect on the enhancement of the electrical properties in the final nanogenerator devices. Cellulose pulp (CP), microcrystalline cellulose (MCC) and cellulose nanofibers (CNFs) were blended with carbon black (CB), carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs). The microstructure of the nanocomposite films was characterized by scanning electron and probe microscopies, and the electrical properties were measured macroscopically and at the local scale by piezoresponse force microscopy. The highest generated output voltage in triboelectric mode was obtained from MCC films with CNTs and CB, while the highest piezoelectric voltage was produced in CNF-CNT films. The obtained electrical responses were discussed in relation to the material properties. Analysis of the microscopic response shows that pulp has a higher local piezoelectric d(33) coefficient (145 pC/N) than CNF (14 pC/N), while the macroscopic response is greatly influenced by the excitation mode and the effective orientation of the crystals relative to the mechanical stress. The increased electricity produced from cellulose nanocomposites may lead to more efficient and biodegradable nanogenerators.


Abril, 2023 | DOI: 10.3390/nano13071206 http://hdl.handle.net/10261/308043

Nanotecnología en Superficies y Plasma

Microstructural Characterization and Self-Propagation Properties of Reactive Al/Ni Multilayers Deposited onto Wavelike Surface Morphologies: Influence on the Propagation Front Velocity

Camposano, YHS; Bartsch, H; Matthes, S; Oliva-Ramirez, M; Jaekel, K; Schaaf, P
Physica Status Solidi A-Applications and Materials Science (2023) 2200765

Reactive multilayer systems are nanostructures of great interest for various technological applications because of their high energy release rate during the self-propagating reaction of their components. Therefore, many efforts are aimed at controlling the propagation velocity of these reactions. Herein, reactive multilayer systems of Al/Ni in the shape of free-standing foils with a wavelike surface morphology prepared by using sacrificial substrates with well-aligned waves are presented and the propagation of the reaction along different directions of the reproduced waves is analyzed. During the ignition test, the propagation front is recorded with a high-speed camera, and the maximum temperature is measured using a pyrometer. The propagation of the reaction is favored in the direction of the waves, which points out the influence of the anisotropy generated by this morphology and how it affects the propagation dynamics and the resulting microstructure. Furthermore, compared to their counterparts fabricated on flat substrates, these reactive multilayers with wavelike morphology exhibit a remarkable reduction in the propagation velocity of the reaction of about 50%, without significantly affecting the maximum temperature registered during the reaction.


Marzo, 2023 | DOI: 10.1002/pssa.202200765

Nanotecnología en Superficies y Plasma

Improved strain engineering of 2D materials by adamantane plasma polymer encapsulation

Carrascoso, F; Li, H; Obrero-Perez, JM; Aparicio, FJ; Borras, A; Island, JO; Barranco, A; Castellanos-Gómez, A
NPJ 2D Materials and Applications, 7 (2023) 24

Two-dimensional materials present exceptional crystal elasticity and provide an ideal platform to tune electrical and optical properties through the application of strain. Here we extend recent research on strain engineering in monolayer molybdenum disulfide using an adamantane plasma polymer pinning layer to achieve unprecedented crystal strains of 2.8%. Using micro-reflectance spectroscopy, we report maximum strain gauge factors of -99.5 meV/% and -63.5 meV/% for the A and B exciton of monolayer MoS2, respectively, with a 50 nm adamantane capping layer. These results are corroborated with photoluminescence and Raman measurements on the same samples. Taken together, our results indicate that adamantane polymer is an exceptional capping layer to transfer substrate-induced strain to a 2D layer and achieve higher levels of crystal strain.


Marzo, 2023 | DOI: 10.1038/s41699-023-00393-1

Nanotecnología en Superficies y Plasma

Incorporation of a Metal Catalyst for the Ammonia Synthesis in a Ferroelectric Packed-Bed Plasma Reactor: Does It Really Matter?

Navascues, P; Garrido-Garcia, J; Cotrino, J; Gonzalez-Elipe, AR; Gomez-Ramirez, A
ACS Sustainable Chemistry & Engineering, 11 (2023) 3621-3632

Plasma-catalysis has been proposed as a potential alternative for the synthesis of ammonia. Studies in this area focus on the reaction mechanisms and the apparent synergy existing between processes occurring in the plasma phase and on the surface of the catalytic material. In the present study, we approach this problem using a parallel-plate packed-bed reactor with the gap between the electrodes filled with pellets of lead zirconate titanate (PZT), with this ferroelectric material modified with a coating layer of alumina (i.e., Al2O3/PZT) and the same alumina layer incorporating ruthenium nanoparticles (i.e., Ru-Al2O3/PZT). At ambient temperature, the electrical behavior of the ferroelectric packed-bed reactor differed for these three types of barriers, with the plasma current reaching a maximum when using Ru-Al2O3/PZT pellets. A systematic analysis of the reaction yield and energy efficiency for the ammonia synthesis reaction, at ambient temperature and at 190 °C and various electrical operating conditions, has demonstrated that the yield and the energy efficiency for the ammonia synthesis do not significantly improve when including ruthenium particles, even at temperatures at which an incipient catalytic activity could be inferred. Besides disregarding a net plasma-catalysis effect, reaction results highlight the positive role of the ferroelectric PZT as moderator of the discharge, that of Ru particles as plasma hot points, and that of the Al2O3 coating as a plasma cooling dielectric layer.


Febrero, 2023 | DOI: 10.1021/acssuschemeng.2c05877

Nanotecnología en Superficies y Plasma

Photoelectrochemical Water Splitting with ITO/WO3/BiVO4/CoPi Multishell Nanotubes Enabled by a Vacuum and Plasma Soft- Template Synthesis

Gil-Rostra, J; Castillo-Seoane, J; Guo, Q; Sobrido, ABJ; Gonzalez-Elipe, AR; Borras, A
ACS Applied Materials & Interfaces, 15 (2023) 9250-9262

A common approach for the photoelectrochemical (PEC) splitting of water relies on the application of WO3 porous electrodes sensitized with BiVO4 acting as a visible photoanode semiconductor. In this work, we propose a new architecture of photoelectrodes consisting of supported multishell nanotubes (NTs) fabricated by a soft-template approach. These NTs are formed by a concentric layered structure of indium tin oxide (ITO), WO3, and BiVO4, together with a final thin layer of cobalt phosphate (CoPi) co-catalyst. The photoelectrode manufacturing procedure is easily implementable at a large scale and successively combines the thermal evaporation of single crystalline organic nanowires (ONWs), the magnetron sputtering deposition of ITO and WO3, and the solution dripping and electrochemical deposition of, respectively, BiVO4 and CoPi, plus the annealing in air under mild conditions. The obtained NT electrodes depict a large electrochemically active surface and outperform the efficiency of equivalent planar-layered electrodes by more than one order of magnitude. A thorough electrochemical analysis of the electrodes illuminated with blue and solar lights demonstrates that the characteristics of the WO3/BiVO4 Schottky barrier heterojunction control the NT electrode efficiency, which depended on the BiVO4 outer layer thickness and the incorporation of the CoPi electrocatalyst. These results support the high potential of the proposed soft-template methodology for the large-area fabrication of highly efficient multishell ITO/WO3/BiVO4/CoPi NT electrodes for the PEC splitting of water.


Febrero, 2023 | DOI: 10.1021/acsami.2c19868

Materiales Nanoestructurados y Microestructura

Microstructure and activity of Pd catalysts prepared on commercial carbon support for the liquid phase decomposition of formic acid

Arzac, GM; Montes, O; Fernández, A
International Journal of Hydrogen Energy, 48 (2023) 2628-2639

In this work, a series of Pd catalysts supported on commercially available activated carbon (Norit (R)) were prepared by employing different metal precursors (Pd(NO3)2 and Na2PdCl4) by the impregnation-reduction method at different pH. Catalysts were tested for the liquid phase decomposition of formic acid to generate hydrogen. The best results, in terms of small particle size and high catalytic activity were achieved for the Pd/C sample prepared by using Pd(NO3)2 salt impregnated at pH = 2.5, and reduced with sodium borohydride. The particle size of the best Pd/C catalyst is (4.1 +/- 1.4) nm with initial TOFs of 2929 and 683 h-1 at 60 and 30 degrees C respectively and an apparent activation energy of 40 kJ mol-1. Samples prepared by using Na2PdCl4 precursor, consisted of particles with higher size and thus lower activity than the ones prepared with Pd(NO3)2. Regardless the Pd precursor employed, the best results in terms of particle size and activity were achieved at the point of zero charge of the support when the Pd species and the carbon surface were both neutral. The impregnation pH not only determines the particle size, but also the nature of the reducing agent does. The catalytic activity was shown to be size-dependent and it was shown that a mixture of surface Pd0 and PdII oxidation states is beneficial for the activity. When comparing with literature catalysts with similar composition, we found that our best catalyst is competitive enough and that Norit (R) support could be promising for future studies on this reaction.


Enero, 2023 | DOI: 10.1016/j.ijhydene.2022.10.149

Nanotecnología en Superficies y Plasma

Determination of the Primary Excitation Spectra in XPS and AES

Pauly, N; Yubero, F; Tougaard, S
Nanomaterials, 13 (2023) 339

This paper reviews a procedure that allows for extracting primary photoelectron or Auger electron emissions from homogeneous isotropic samples. It is based on a quantitative dielectric description of the energy losses of swift electrons travelling nearby surfaces in presence of stationary positive charges. The theory behind the modeling of the electron energy losses, implemented in a freely available QUEELS-XPS software package, takes into account intrinsic and extrinsic effects affecting the electron transport. The procedure allows for interpretation of shake-up and multiplet structures on a quantitative basis. We outline the basic theory behind it and illustrate its capabilities with several case examples. Thus, we report on the angular dependence of the intrinsic and extrinsic Al 2s photoelectron emission from aluminum, the shake-up structure of the Ag 3d, Cu 2p, and Ce 3d photoelectron emission from silver, CuO and CeO2, respectively, and the quantification of the two-hole final states contributing to the L3M45M45 Auger electron emission of copper. These examples illustrate the procedure, that can be applied to any homogeneous isotropic material.


Enero, 2023 | DOI: 10.3390/nano13020339

Nanotecnología en Superficies y Plasma

A Holistic Solution to Icing by Acoustic Waves: De-Icing, Active Anti-Icing, Sensing with Piezoelectric Crystals, and Synergy with Thin Film Passive Anti-Icing Solutions

Del Moral, J; Montes, L; Rico-Gavira, VJ; Lopez-Santos, C; Jacob, S; Oliva-Ramirez, M; Gil-Rostra, J; Fakhfouri, A; Pandey, S; Del Val, MG; Mora, J; García-Gallego, P; Ibanez-Ibanez, PF; Rodríguez Valverde, MA; Winkler, A; Borras, A; Gonzalez-Elipe, AR
Advanced Functional Materials, 33 (2023) 2209421

Icing has become a hot topic both in academia and in the industry given its implications in transport, wind turbines, photovoltaics, and telecommunications. Recently proposed de-icing solutions involving the propagation of acoustic waves (AWs) at suitable substrates may open the path for a sustainable alternative to standard de-icing or anti-icing procedures. Herein, the fundamental interactions are unraveled that contribute to the de-icing and/or hinder the icing on AW-activated substrates. The response toward icing of a reliable model system consisting of a piezoelectric plate activated by extended electrodes is characterized at a laboratory scale and in an icing wind tunnel under realistic conditions. Experiments show that surface modification with anti-icing functionalities provides a synergistic response when activated with AWs. A thoughtful analysis of the resonance frequency dependence on experimental variables such as temperature, ice formation, or wind velocity demonstrates the application of AW devices for real-time monitoring of icing processes.


Enero, 2023 | DOI: 10.1002/adfm.202209421 http://hdl.handle.net/10261/354924



2022


Materiales Nanoestructurados y Microestructura

Pd supported on defective TiO2 polymorphic mixtures: Effect of metal-support interactions upon glycerol selective oxidation

Rinaudo, MG; Beltran, AM; Fernandez, A; Cadus, LE; Morales, MR
Results in Engineering, 16 (2022) 100737

Palladium catalysts supported on defective mixes of anatase, TiO2 (II) and rutile crystalline phases, previously obtained by high-energy ball milling, were synthesized and tested for glycerol selective oxidation. A deep characterization of these unusual materials was carried out to elucidate catalytic and physicochemical features. Electron density transfer from support to metal or vice versa, depending on the polymorphs present, could not only alter palladium particle sizes and its surface oxidation state but also reducibility and oxygen mobility of catalysts. Furthermore, acid-base properties achieved also influenced catalytic activity under mild conditions of liquid-phase glycerol oxidation. A conversion of 94% and a selectivity to glyceric and lactic acids of 48% and 22% respectively were obtained for the Pd catalyst supported on mechanochemically activated anatase. The presence of several polymorphs in a metal oxide support could therefore benefit or handicap catalytic cycle for a particular reaction. Metal-support interactions play a key role in heterogenous catalysts and thus the rational design of supports comes on the scene.


Diciembre, 2022 | DOI: 10.1016/j.rineng.2022.100737

Tribología y Protección de Superficies

High-Quality SiO2/O-Terminated Diamond Interface: Band-Gap, Band-Offset and Interfacial Chemistry

Canas, J; Reyes, DF; Zakhtser, A; Dussarrat, C; Teramoto, T; Gutierrez, M; Gheeraert, E
Nanomaterials, 12 (2022) 4125

Silicon oxide atomic layer deposition synthesis development over the last few years has open the route to its use as a dielectric within diamond electronics. Its great band-gap makes it a promising material for the fabrication of diamond-metal-oxide field effects transistor gates. Having a sufficiently high barrier both for holes and electrons is mandatory to work in accumulation and inversion regimes without leakage currents, and no other oxide can fulfil this requisite due to the wide diamond band-gap. In this work, the heterojunction of atomic-layer-deposited silicon oxide and (100)-oriented p-type oxygen-terminated diamond is studied using scanning transmission electron microscopy in its energy loss spectroscopy mode and X-ray photoelectron spectroscopy. The amorphous phase of silicon oxide was successfully synthesized with a homogeneous band-gap of 9.4 eV. The interface between the oxide and diamond consisted mainly of single- and double-carbon-oxygen bonds with a low density of interface states and a straddling band setting with a 2.0 eV valence band-offset and 1.9 eV conduction band-offset.


Diciembre, 2022 | DOI: 10.3390/nano12234125

Materiales Nanoestructurados y Microestructura

Morphologically diverse CaCO3 microparticles and their incorporation into recycled cellulose for circular economy

Guerra-Garces, J; Garcia-Negrete, CA; Pastor-Sierra, K; Arteaga, GC; Barrera-Vargas, M; de Haro, MJ; Fernandez, A
Materials Today Sustainability, 19 (2022) 100166

The main raw material for manufacture of paper is cellulose fibers that can be virgin or recycled. Globally, 70% of the Tetra Pak packages sold are not recycled and remain as unused wastes. Therefore, the development of alternatives to promote greater recycling and sustainable use of these packages is of great interest. In this study, the formation of precipitated calcium carbonates (PCC) in the presence of carboxymethyl cellulose (CMC) is studied at different temperatures, and the morphologically diverse particles obtained are explored as filler for composites based on cellulosic fibers recovered from Tetra Pak containers. It was found that the addition of filler does not lead to deterioration of either tensile strength or thermal and stability of the obtained composite samples. Results also suggest that the morphological diversity of the filler contributes to a more efficient filling of the interfibrillar spaces of cellulosic fibers and, in turn, to the fiber and filler compatibility.


Noviembre, 2022 | DOI: 10.1016/j.mtsust.2022.100166

Nanotecnología en Superficies y Plasma

Design and Characterization of ITO-Covered Resonant Nanopillars for Dual Optical and Electrochemical Sensing

Tramarin, L; Casquel, R; Gil-Rostra, J; Gonzalez-Martinez, MA; Herrero-Labrador, R; Murillo, AMM; Laguna, MF; Banuls, MJ; Gonzalez-Elipe, AR; Holgado, M
Chemosensors, 10 (2022) 393

In this work we present a dual optical and electrochemical sensor based on SiO2/Si3N4 resonant nanopillars covered with an indium tin oxide (ITO) thin film. A 25-30 nm thick ITO layer deposited by magnetron sputtering acts as an electrode when incorporated onto the nanostructured array, without compromising the optical sensing capability of the nanopillars. Bulk sensing performances before and after ITO deposition have been measured and compared in accordance with theoretical calculations. The electrochemical activity has been determined by the ferri/ferrocyanide redox reaction, showing a remarkably higher activity than that of flat thin films of similar ITO nominal thickness, and proving that the nanopillar system covered by ITO presents electrical continuity. A label-free optical biological detection has been performed, where the presence of amyloid-beta has been detected through an immunoassay enhanced with gold nanoparticles. Again, the experimental results have been corroborated by theoretical simulations. We have demonstrated that ITO can be a beneficial component for resonant nanopillars sensors by adding potential electrochemical sensing capabilities, without significantly altering their optical properties. We foresee that resonant nanopillars coated with a continuous ITO film could be used for simultaneous optical and electrochemical biosensing, improving the robustness of biomolecular identification.


Octubre, 2022 | DOI: 10.3390/chemosensors10100393

Nanotecnología en Superficies y Plasma

Multiscale Kinetic Monte Carlo Simulation of Self-Organized Growth of GaN/AlN Quantum Dots

Budagosky, JA; García-Cristobal, A
Nanomaterials, 12 (2022) 3052

A three-dimensional kinetic Monte Carlo methodology is developed to study the strained epitaxial growth of wurtzite GaN/AlN quantum dots. It describes the kinetics of effective GaN adatoms on an hexagonal lattice. The elastic strain energy is evaluated by a purposely devised procedure: first, we take advantage of the fact that the deformation in a lattice-mismatched heterostructure is equivalent to that obtained by assuming that one of the regions of the system is subjected to a properly chosen uniform stress (Eshelby inclusion concept), and then the strain is obtained by applying the Green's function method. The standard Monte Carlo method has been modified to implement a multiscale algorithm that allows the isolated adatoms to perform long diffusion jumps. With these state-of-the art modifications, it is possible to perform efficiently simulations over large areas and long elapsed times. We have taylored the model to the conditions of molecular beam epitaxy under N-rich conditions. The corresponding simulations reproduce the different stages of the Stranski-Krastanov transition, showing quantitative agreement with the experimental findings concerning the critical deposition, and island size and density. The influence of growth parameters, such as the relative fluxes of Ga and N and the substrate temperature, is also studied and found to be consistent with the experimental observations. In addition, the growth of stacked layers of quantum dots is also simulated and the conditions for their vertical alignment and homogenization are illustrated. In summary, the developed methodology allows one to reproduce the main features of the self-organized quantum dot growth and to understand the microscopic mechanisms at play.


Septiembre, 2022 | DOI: 10.3390/nano12173052

Nanotecnología en Superficies y Plasma

Optimization of anion exchange membrane water electrolyzers using ionomer-free electrodes

Lopez-Fernandez, E; Gomez-Sacedon, C; Gil-Rostra, J; Espinos, JP; Brey, JJ; Gonzalez-Elipe, AR; de Lucas-Consuegra, A.; Yubero, F
Renewable Energy, 197 (2022) 1183-1191

This work is carried out in the context of the anion exchange membrane water electrolysis (AEMWE) and pursuits to determine the influence of different cell components on the global electrochemical performance. Ionomer-free electrodes consisting of anodic Ni-Fe and cathodic Ni electrocatalysts deposited by magnetron sputtering in an oblique angle deposition configuration were utilized for this study. In addition to the characteristics and equivalent thickness of the electrocatalysts, other factors affecting the efficiency that have been considered in this study encompass the type of gas diffusion layer (GDLs), including carbon paper and stainless-steel fiber paper supports, and several commercial anion exchange membranes. The electrocatalytic performances in both a threeelectrode and complete single cell AEMWE set-ups, together with the physico-chemical characterization of the electrodes before and after operation, have served to select the optimum components for the utilized cell configuration. Thus, current densities of 670 mA cm-2, at polarization voltage of 2.2 V, 1.0 M KOH electrolyte and 40 degrees C were obtained in a membrane electrode assembly. A seven days chronopotentiometry experiment at a fixed current of 400 mA cm-2 demonstrated a noticeable stability of this type of AEMWE cells incorporating ionomer-free electrodes.


Septiembre, 2022 | DOI: 10.1016/j.renene.2022.08.013

Tribología y Protección de Superficies

Influence of the carbon incorporation on the mechanical properties of TiB2 thin films prepared by HiPIMS

Sala, N; Abad, MD; Sanchez-Lopez, JC; Crugeira, F; Ramos-Masana, A; Colominas, C
International Journal of Refractory Metals & Hard Materials, 107 (2022) 105884

Nanostructured TiB2 and TiBC thin films with carbon contents up to 11 at. % were prepared by physical vapor deposition using high power impulse magnetron sputtering (HiPIMS) technology. The influence of carbon incorporation during the deposition of TiB2 coatings was investigated on the chemical composition, microstructure and mechanical properties by means of scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), nanoindentation, scratch test, calotest and adhesion Daimler-Benz test. The results indicated that small additions of carbon up to 3 at. % improved the mechanical behavior and increased the adhesion of the TiB2 thin films. Hardnesses up to 37 GPa were reached and the adhesion of the coating to AISI D2 steel substrates increased from 11 to 18 N. XRD and XPS results showed that the carbon atoms are either occupying interstitial sites within the hexagonal structure of the TiB2 or forming bonds with titanium and boron atoms. The preferred orientation of the films determined by XRD also changed with the increasing carbon content in the (001) crystalline plane.


Septiembre, 2022 | DOI: 10.1016/j.ijrmhm.2022.105884

Materiales para Bioingeniería y Regeneración Tisular

Sol-Gel Synthesis of Endodontic Cements: Post-Synthesis Treatment to Improve Setting Performance and Bioactivity

Song, X; Diaz-Cuenca, A
Materials, 15 (2022) 6051

The sol-gel process is a wet chemical technique that allows very fine control of the composition, microstructure, and final textural properties of materials, and has great potential for the synthesis of endodontic cements with improved properties. In this work, the influence of different sol-gel synthesis variables on the preparation of endodontic cement based on calcium silicate with Ca/Si stoichiometry equal to 3 was studied. Starting from the most optimal hydraulic composition selected, a novel second post-synthesis treatment using ethanol was essayed. The effects of the tested variables were analyzed by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen physisorption, and Gillmore needles to determine the setting time and simulated body fluid (SBF) immersion to measure the bioactive response in vitro. The results indicated that the sol-gel technique is effective in obtaining bioactive endodontic cements (BECs) with high content of the hydraulic compound tricalcium silicate (C3S) in its triclinic polymorph. The implementation of a novel post-synthesis treatment at room temperature using ethanol allows obtaining a final BEC product with a finer particle size and a higher CaCO3 content, which results in an improved material in terms of setting time and bioactive response.


Septiembre, 2022 | DOI: 10.3390/ma15176051

Nanotecnología en Superficies y Plasma

One-Dimensional Photonic Crystal for Surface Mode Polarization Control

Mogni, E; Pellegrini, G; Gil-Rostra, J; Yubero, F; Simone, G; Fossati, S; Dostalek, J; Vazquez, RM; Osellame, R; Celebrano, M; Finazzi, M; Biagioni, P
Advanced Optical Materials, (2022) 2200759

Bloch surface waves sustained by truncated 1D photonic crystals (1DPCs) are well known tools for surface-enhanced spectroscopy. They provide strongly confined fields with uniform distribution over a large surface area, a characteristic exploited in standard refractometric sensing. However, their application to polarization-sensitive investigations is not straightforward because the transverse electric (TE) and magnetic (TM) surface modes possess distinct dispersion relations, therefore their relative phase is not conserved along propagation and the polarization state of any wave obtained by combining these modes is ill-defined. In this work, a novel design of a 1DPC is realized in which the TE and TM modes exhibit the same phase velocity over a broadband spectral range and thus their dispersion relations overlap. The capability to simultaneously excite TE and TM modes with a well-defined phase relation allows the generation of surface waves with a controlled polarization state. This paves the way to polarization-resolved surface-enhanced analysis, including, for example, linear and circular dichroism spectroscopy of grafted molecular layers at the photonic crystal surface.


Agosto, 2022 | DOI: 10.1002/adom.202200759

Materiales Nanoestructurados y Microestructura

Ultrathin Plasma Polymer Passivation of Perovskite Solar Cells for Improved Stability and Reproducibility

Obrero-Perez, JM; Contreras-Bernal, L; Nuñez-Galvez, F; Castillo-Seoane, J; Valadez-Villalobos, K; Aparicio, FJ; Anta, JA; Borras, A; Sanchez-Valencia, JR; Barranco, A
Advanced Energy Materials, (2022) 2200812

Despite the youthfulness of hybrid halide perovskite solar cells, their efficiencies are currently comparable to commercial silicon and have surpassed quantum-dots solar cells. Yet, the scalability of these devices is a challenge due to their low reproducibility and stability under environmental conditions. However, the techniques reported to date to tackle such issues recurrently involve the use of solvent methods that would further complicate their transfer to industry. Herein a reliable alternative relaying in the implementation of an ultrathin plasma polymer as a passivation interface between the electron transport layer and the hybrid perovskite layer is presented. Such a nanoengineered interface provides solar devices with increased long-term stability under ambient conditions. Thus, without involving any additional encapsulation step, the cells retain more than 80% of their efficiency after being exposed to the ambient atmosphere for more than 1000 h. Moreover, this plasma polymer passivation strategy significantly improves the coverage of the mesoporous scaffold by the perovskite layer, providing the solar cells with enhanced performance, with a champion efficiency of 19.2%, a remarkable value for Li-free standard mesoporous n-i-p architectures, as well as significantly improved reproducibility.


Julio, 2022 | DOI: 10.1002/aenm.202200812

Nanotecnología en Superficies y Plasma

Comparative analysis of the germination of barley seeds subjected to drying, hydrogen peroxide, or oxidative air plasma treatments

Perea-Brenes, A; Gomez-Ramirez, A; Lopez-Santos, C; Oliva-Ramirez, M; Molina, R; Cotrino, J; García, JL; Cantos, M; González-Elipe, ARA
Plasma Processes and Polymers 19 (2022) e2200035

Acceleration in germination time by 12-24 h for barley seeds treated with atmospheric air plasmas may have a significant economic impact on malting processes. In this study, the increase in germination rate and decrease in contamination level upon plasma treatment could not be directly correlated with any significant increase in the water uptake capacity, except for seeds exposed to mild drying treatment. A variety of germination essays have been carried out with seeds impregnated with an abscisic acid solution, a retarding factor of germination, treated with a peroxide solution, and/or subjected to the plasma and drying treatments. Results suggest that plasma and hydrogen peroxide treatments induce the formation of reactive oxygen and nitrogen species that affects the abscisic acid factor and accelerate the germination rate.


Junio, 2022 | DOI: 10.1002/ppap.202200035

Nanotecnología en Superficies y Plasma

Electron beam evaporated vs. magnetron sputtered nanocolumnar porous stainless steel: Corrosion resistance, wetting behavior and anti-bacterial activity

Bobaru, S; Rico-Gavira, V; Garcia-Valenzuela, A; Lopez-Santos, C; Gonzalez-Elipe, AR
Materials Today Communications, 31 (2022) 103266

Stainless steel (SS), widely used because of its outstanding corrosion protection properties, does not possess any particular anti-stain or anti-bacterial activity as required for household and sanitary applications. This work reports the fabrication of SS thin films that, keeping a similar corrosion resistance than the bulk material, presents hydrophobicity and anti-bacterial activity. These thin films are prepared at ambient temperature by physical vapor deposition (PVD), either electron beam evaporation (EBE) or magnetron sputtering (MS), at oblique angles (OAD). According to their scanning electron microcopy and atomic force microscopy analysis, the microstructure of the OAD-SS thin films consisted of tilted and separated nanocolumns defining a surface topology that, characterized by a high percentage of void space, varied with the deposition conditions and procedure, either EBE or MS. It has been shown that particularly the nanocolumnar MS-OAD thin films preserved and even improved the high corrosion resistance of compact SS, as determined by electrochemical analysis. Besides, all OAD-SS thin films depict hydrophobicity and a high antibacterial activity. These features, particularly remarkable for the MS-OAD thin films, have been related with their tip-like termination at the surface and the existence of large void spaces separating the nanocolumns. This topology appears to affect negatively the bacteria's deployment onto the surface and therefore the survival rate. Differences in the corrosion and antibacterial performance between EBE and MS-OAD thin films have been related with the specificities of these two PVD methods of thin film preparation. A relatively high abrasion resistance, as determined by abrasion tests, supports the use of MS-OAD thin films for the protection of commodity materials.


Junio, 2022 | DOI: 10.1016/j.mtcomm.2022.103266

Nanotecnología en Superficies y Plasma

Nanostructured nickel based electrocatalysts for hybrid ethanol-water anion exchange membrane electrolysis

Lopez-Fernandez, E; Gomez-Sacedon, C; Gil-Rostra, J; Espinos, JP; Gonzalez-Elipe, AR; Yubero, F
Journal of Environmental Chemical Engineering, 10 (2022) 107994

Ni and Ni-Fe nanostructured layers prepared by magnetron sputtering in an oblique angle deposition configuration (MS-OAD) have been used as anode and cathode catalysts for hybrid ethanol-water electrolysis in an anion exchange membrane (AEM) electrolyser. Physico-chemical and electrochemical characterization in a threeelectrode cell has been carried out to determine the optimal characteristics of the anodic films. Current densities up to 434 mA cm-2 at 2.0 V in a 1.5 M EtOH and 2.0 M KOH fuel solution were achieved with excellent operational stability for 3 days. These experiments show that the oxygen evolution reaction taking place at the anode is completely replaced by the ethanol oxidation reaction under our explored reaction conditions. The obtained results evidence the interest of this kind of organic vs. pure water electrolysis to decrease the overall electrical energy consumption for the production of hydrogen.


Junio, 2022 | DOI: 10.1016/j.jece.2022.107994

Nanotecnología en Superficies y Plasma

Titania Enhanced Photocatalysis and Dye Giant Absorption in Nanoporous 1D Bragg Microcavities

Rico, VJ; Turk, H; Yubero, F; González-Elipe, AR
ACS Applied Nano Materials, 5 (2022) 5487-5497

Light trapping effects are known to boost the photocatalytic degradation of organic molecules in 3D photonic structures of anatase titania (a-TiO2) with an inverse opal configuration. In the present work, we show that photocatalytic activity can also be enhanced in a-TiO2 thin films if they are incorporated within a nanoporous 1D optical resonant microcavity. We have designed and manufactured multilayer systems that, presenting a high open porosity to enable a straightforward diffusion of photodegradable molecules, provide light confinement effects at wavelengths around the absorption edge of photoactive a-TiO2. In brief, we have observed that a nanoporous 1D Bragg microcavity prepared by electron beam evaporation at oblique angles comprising a central defect layer of nanoporous a-TiO2 boosts the photocatalytic degradation of nitrobenzene and methyl orange dye solutions. The multilayer structure of the microcavity was designed to ensure the appearance of optical resonances at the a-TiO2 layer location and wavelengths around the absorption onset of this semiconductor. In this porous 1D Bragg microcavity, the diffusion constraints of molecules through the capping layers covering the a-TiO2 are effectively compensated by an increase in the photocatalytic activity due to the light confinement phenomena. We also report that the absorption coefficient of methyl orange dye solution infiltrated within the pore structure of the microcavity is exalted at the wavelengths of the corresponding optical resonances. This effect gives rise to a small but non-negligible visible light photodegradation of dye molecules. The possibilities of tailoring the design of 1D photonic systems to boost the photocatalytic activity of a-TiO2 are discussed.


Junio, 2022 | DOI: 10.1021/acsanm.2c00477

Nanotecnología en Superficies y Plasma

Role of Surface Topography in the Superhydrophobic Effect-Experimental and Numerical Studies

Ibrahim, SH; Wejrzanowski, T; Przybyszewski, B; Kozera, R; Garcia-Casas, X; Barranco, A
Materials, 15 (2022) 3112

Within these studies, the effect of surface topography for hydrophobic coatings was studied both numerically and experimentally. Chemically modified polyurethane coating was patterned by application of a laser beam. A set of patterns with variously distant linear peaks and grooves was obtained. The cross section of the pattern showed that the edges of the peaks and grooves were not sharp, instead forming a rounded, rectangle-like shape. For such surfaces, experimental studies were performed, and in particular the static contact angle (SCA), contact angle hysteresis (CAH), and roll-off angle (ROA) were measured. Profilometry was used to create a numerical representation of the surface. Finite volume method was then applied to simulate the behavior of the water droplets. The model developed herewith enabled us to reproduce the experimental results with good accuracy. Based on the verified model, the calculation was extended to study the behavior of the water droplet on the simulated patterns, both spiked and rectangular. These two cases, despite a similar SCA of the water droplet, have shown extremely different ROA. Thus, more detailed studies were dedicated to other geometrical features of such topography, such as the size and distance of the surface elements. Based on the results obtained herewith, the future design of superhydrophobic and/or icephobic topography is discussed.


Mayo, 2022 | DOI: 10.3390/ma15093112

Nanotecnología en Superficies y Plasma

Analysis of the effect of cationic ratio Bi3+/Fe3+ on the magnetic and multiferroic properties of BiFeO3 nanoparticles synthesized using a sonochemical-assisted method

Palomino-Resendiz, RL; Bolarin-Miro, AM; Pedro-Garcia, F; Sanchez-De Jesus, F; Espinos-Manzorro, JP; Cortes-Escobes-Escobedo, CA
Ceramics International, 48 (2022) 14746-14753

This study examined the effects of the cationic ratio of Bi3+/Fe3+ via X-ray photoelectron spectroscopy (XPS) on the magnetic and multiferroic properties of BiFeO3 nanoparticles synthesized using a sonochemical-assisted method. X-ray diffraction revealed the successful synthesis of single-phase BiFeO3 powder after annealing the sonicated material at 723 K. The powder was composed of agglomerates of rounded particles with a mean particle size of 35 nm. XPS was performed to determine the Bi3+/Fe3+ ratio as a function of the heat treatment process and its relationship with secondary phases, which can modulate the magnetic properties of the nano powders. The cationic ratio obtained by XPS confirmed that the powders obtained at 623 and 923 K have excess Bi3+ and Fe3+, respectively, which induces the formation of Bi24Fe2O39 and Bi2Fe4O9 as the majority phases. Powder annealing at 723 K revealed a ferromagnetic order with specific magnetization of 1.8 Am-2/kg. This ferromagnetic behavior was preserved after applying spark plasma sintering (SPS) at 923 K. By contrast, conventional sintering at 1023 K promotes antiferromagnetic order. In addition, the dielectric properties of the ceramic material of the sintered powders showed a behavior related to a typical ferroelectric material.


Mayo, 2022 | DOI: 10.1016/j.ceramint.2022.02.011

Nanotecnología en Superficies y Plasma

Influence of Femtosecond Laser Modification on Biomechanical and Biofunctional Behavior of Porous Titanium Substrates

Beltran, AM; Giner, M; Rodríguez, A; Trueba, P; Rodríguez-Albelo, LM; Vázquez-Gámez, MA; Godinho, V; Alcudia, A; Amado, JM; López-Santos, C; Yadir, T
Materials, 15 (2022) 2969

Bone resorption and inadequate osseointegration are considered the main problems of titanium implants. In this investigation, the texture and surface roughness of porous titanium samples obtained by the space holder technique were modified with a femtosecond Yb-doped fiber laser. Different percentages of porosity (30, 40, 50, and 60 vol.%) and particle range size (100-200 and 355-500 mu m) were compared with fully-dense samples obtained by conventional powder metallurgy. After femtosecond laser treatment the formation of a rough surface with micro-columns and micro-holes occurred for all the studied substrates. The surface was covered by ripples over the micro-metric structures. This work evaluates both the influence of the macro-pores inherent to the spacer particles, as well as the micro-columns and the texture generated with the laser, on the wettability of the surface, the cell behavior (adhesion and proliferation of osteoblasts), micro-hardness (instrumented micro-indentation test, P-h curves) and scratch resistance. The titanium sample with 30 vol.% and a pore range size of 100-200 mu m was the best candidate for the replacement of small damaged cortical bone tissues, based on its better biomechanical (stiffness and yield strength) and biofunctional balance (bone in-growth and in vitro osseointegration).


Mayo, 2022 | DOI: 10.3390/ma15092969

Materiales para Bioingeniería y Regeneración Tisular

Mesoporous Silica-Based Nanoparticles as Non-Viral Gene Delivery Platform for Treating Retinitis Pigmentosa

Valdes-Sanchez, L; Borrego-González, S; Montero-Sanchez, A; Massalini, S; De la Cerda, B; Díaz-Cuenca, A; Díaz-Corrales, FJ
Journal of Clinical Medicine, 11 (2022) 2170

Background: Gene therapy is a therapeutic possibility for retinitis pigmentosa (RP), in which therapeutic transgenes are currently delivered to the retina by adeno-associated viral vectors (AAVs). Although their safety and efficacy have been demonstrated in both clinical and preclinical settings, AAVs present some technical handicaps, such as limited cargo capacity and possible immunogenicity in repetitive doses. The development of alternative, non-viral delivery platforms like nanoparticles is of great interest to extend the application of gene therapy for RP. Methods: Amino-functionalized mesoporous silica-based nanoparticles (N-MSiNPs) were synthesized, physico-chemically characterized, and evaluated as gene delivery systems for human cells in vitro and for retinal cells in vivo. Transgene expression was evaluated by WB and immunofluorescence. The safety evaluation of mice subjected to subretinal injection was assessed by ophthalmological tests (electroretinogram, funduscopy, tomography, and optokinetic test). Results: N-MSiNPs delivered transgenes to human cells in vitro and to retinal cells in vivo. No adverse effects were detected for the integrity of the retinal tissue or the visual function of treated eyes. N-MSiNPs were able to deliver a therapeutic transgene candidate for RP, PRPF31, both in vitro and in vivo. Conclusions: N-MSiNPs are safe for retinal delivery and thus a potential alternative to viral vectors.


Abril, 2022 | DOI: 10.3390/jcm11082170

Nanotecnología en Superficies y Plasma

Ionomer-Free Nickel-Iron bimetallic electrodes for efficient anion exchange membrane water electrolysis

Lopez-Fernandez, E; Gomez-Sacedon, C; Gil-Rostra, J; Espinos, JP; Gonzalez-Elipe, AR; Yubero, F; De Lucas-Consuegra, A
Chemical Engineering Journal, 433 (2022) 133774

A bottleneck for the deployment of the Anion Exchange Membrane Water Electrolysis (AEMWE) is the manufacturing of efficient and long lasting anodes and cathodes for the cells. Highly performant bimetallic Ni/Fe catalyst films with various atomic ratios have been prepared by magnetron sputtering in an oblique angle configuration (MS-OAD) and used as anodes for AEMWE. Electrocatalytic experiments in a small three-electrode cell and a thorough analysis of the electrode properties with various physico-chemical characterization tech-niques have been used to select the nanostructured anode catalyst which, depicting an optimized Ni/Fe ratio, presents the maximum activity for the oxygen evolution reaction. These anode layers are then scale-up for their integration in an AEMWE cell where the influence of assembly conditions and the effect of adding an ionomer to the anodes have been studied. The obtained results have demonstrated the outstanding properties of the fabri-cated bimetallic films in terms of activity, stability, and operation under ionomer-free conditions. Current density values around 400 and 600 mA cm(-2) at 40??& nbsp;and 60 C (2.0 V), respectively, much higher than those obtained with pure Ni, were obtained with an optimized membrane electrode assembly. The high yield obtained with these electrodes gains further relevance when considering that the current yield per unit mass of the anodic active phase catalyst (i.e., 1086 mA mg(-1) at 2.0 V and 40??) is the highest among equivalent values reported in literature. The possibilities and prospects of the use of bimetallic catalyst films prepared by MS-OAD for AEMWE are discussed.


Abril, 2022 | DOI: 10.1016/j.cej.2021.133774

Nanotecnología en Superficies y Plasma

Thin film nanostructuring at oblique angles by substrate patterning

Muñoz-Pina, S; Alcaide, AM; Limones-Ahijon, B; Oliva-Ramirez, M; Rico, V; Alcala, G; Gonzalez, MU; García-Martín, JM; Alvarez, R; Wang, D; Schaaf, P; Gonzalez-Elipe, AR; Palmero, A
Surface & Coatings Technology, 436 (2022) 128293

It is demonstrated that, besides classical nanocolumnar arrays, the oblique angle geometry induces the growth of singular structures in the nanoscale when using wisely designed patterned substrates. Well-ordered array of crosses, cylindrical nanorods or hole structures arranged in square or hexagonal regular geometries are reported as examples, among others. The fundamental framework connecting substrate topography and film growth at oblique angles is presented, allowing the use of substrate patterning as a feasible thin film nanostructuring technique. A systematic analysis of the growth of TiO2 thin films on 4 different lithographic patterned substrates in 4 different scale lengths is also presented. A first conclusion is the existence of a height-based selective growth in the initial stages of the deposition, by which the film preferentially develops on top of the tallest substrate features. This behavior is maintained until the film reaches a critical thickness, the so-called Oblivion Thickness, above which the film topography becomes gradually independent of the substrate features. A general formula relating the spatial features of the pattern, the coarsening exponent and the Oblivion Thickness has been deduced.


Abril, 2022 | DOI: 10.1016/j.surfcoat.2022.128293

Nanotecnología en Superficies y Plasma

QUEELS: Software to calculate the energy loss processes in TEELS, REELS, XPS and AES including effects of the core hole

Tougaard, S; Pauly, N; Yubero, F
Surface and Interface Analysis, 54 (2022) 820-833

We present the user-friendly and freely available software package QUEELS (QUantitative analysis of Electron Energy Losses at Surfaces) that allows to calculate effective inelastic scattering cross sections within the dielectric response description, for swift electrons travelling nearby surfaces in several environments. We briefly describe the underlying theoretical models and illustrate its use to evaluate the distribution of energy losses taking place in electron spectroscopies like transmission electron energy loss spectroscopy (TEELS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS), which are widely used for material analysis. This includes the intrinsic excitations due to the core hole in XPS and AES.


Abril, 2022 | DOI: 10.1002/sia.7095

Nanotecnología en Superficies y Plasma

Multiscale ultrafast laser texturing of marble for reduced surface wetting

Ariza, R; Alvarez-Alegria, M; Costas, G; Tribaldo, L; Gonzalez-Elipe, AR; Siegel, J; Solis, J
Applied Surface Science, 577 (2022) 152850

The modification of the wetting properties of marble surfaces upon multi-scale texturing induced by ultrafast laser processing (340 fs pulse duration, 1030 nm wavelength) has been investigated with the aim of evaluating its potential for surface protection. The contact angle (CA) of a water drop placed on the surface was used to assess the wettability of the processed areas. Although the surfaces are initially hydrophilic upon laser treatment, after a few days they develop a strong hydrophobic behavior. Marble surfaces have been irradiated with different scan line separations to elucidate the relative roles of multi-scale roughness (nano-and micro-texture) and chemical changes at the surface. The time evolution of the contact angle has been then monitored up to 11 months after treatment. A short and a long-term evolution, associated to the combined effect of multi-scale roughness and the attachment of chemical species at the surface over the time, have been observed. XPS and ATR measurements are consistent with the progressive hydroxylation of the laser treated surfaces although the additional contribution of hydrocarbon adsorbates to the wettability evolution cannot be ruled-out. The robustness of the results has been tested by CA measurements after cleaning in different conditions with very positive results.


Marzo, 2022 | DOI: 10.1016/j.apsusc.2021.151850

Nanotecnología en Superficies y Plasma - Materiales Nanoestructurados y Microestructura

Highly Anisotropic Organometal Halide Perovskite Nanowalls Grown by Glancing-Angle Deposition

Castillo-Seoane, J; Contreras-Bernal, L; Obrero-Perez, JM; Garcia-Casas, X; Lorenzo-Lazaro, F; Aparicio, FJ; Lopez-Santos, C; Rojas, TC; Anta, JA; Borras, A; Barranco, A; Sanchez-Valencia, JR
Advanced Materials (2022) 2107739

Polarizers are ubiquitous components in current optoelectronic devices as displays or photographic cameras. Yet, control over light polarization is an unsolved challenge, since the main drawback of the existing display technologies is the significant optical losses. In such a context, organometal halide perovskites (OMHP) can play a decisive role given their flexible synthesis with tunable optical properties such as bandgap and photoluminescence, and excellent light emission with a low non-radiative recombination rate. Therefore, along with their outstanding electrical properties have elevated hybrid perovskites as the material of choice in photovoltaics and optoelectronics. Among the different OMHP nanostructures, nanowires and nanorods have lately arisen as key players in the control of light polarization for lighting or detector applications. Herein, the fabrication of highly aligned and anisotropic methylammonium lead iodide perovskite nanowalls by glancing-angle deposition, which is compatible with most substrates, is presented. Their high alignment degree provides the samples with anisotropic optical properties such as light absorption and photoluminescence. Furthermore, their implementation in photovoltaic devices provides them with a polarization-sensitive response. This facile vacuum-based approach embodies a milestone in the development of last-generation polarization-sensitive perovskite-based optoelectronic devices such as lighting appliances or self-powered photodetectors.


Marzo, 2022 | DOI: 10.1002/adma.202107739

Nanotecnología en Superficies y Plasma

Rhodamine 6G and 800 intermolecular heteroaggregates embedded in PMMA for near-infrared wavelength shifting

Castillo-Seoane, J; Gonzalez-García, L; Obrero-Pérez, JM; Aparicio, FJ; Borras, A; Gonzalez-Elipe, AR; Barranco, A; Sanchez-Valencia, JR
Journal of Materials Chemistry C, 10 (2022) 7119-7131

The opto-electronic properties of small-molecules and functional dyes usually differ when incorporated into solid matrices with respect to their isolated form due to an aggregation phenomenon that alters their optical and fluorescent properties. These spectroscopic modifications are studied in the framework of the exciton theory of aggregates, which has been extensively applied in the literature for the study of molecular aggregates of the same type of molecules (homoaggregation). Despite the demonstrated potential of the control of the heteroaggregation process (aggregation of different types of molecules), most of the reported works are devoted to intramolecular aggregates, complex molecules formed by several chromophores attached by organic linkers. The intramolecular aggregates are specifically designed to hold a certain molecular structure that, on the basis of the exciton theory, modifies their optical and fluorescent properties with respect to the isolated chromophores that form the molecule. The present article describes in detail the incorporation of Rhodamine 6G (Rh6G) and 800 (Rh800) into polymeric matrices of poly-(methyl methacrylate), PMMA. The simultaneous incorporation of both dyes results in an enhanced fluorescent emission in the near-infrared (NIR), originating from the formation of ground-state Rh6G-Rh800 intermolecular heteroaggregates. The systematic control of the concentration of both rhodamines provides a model system for the elucidation of the heteroaggregate formation. The efficient energy transfer between Rh6G and Rh800 molecules can be used as wavelength shifters to convert effectively the light from visible to NIR, a very convenient wavelength range for many practical applications which make use of inexpensive commercial detectors and systems.


Marzo, 2022 | DOI: 10.1039/d1tc06167d

Nanotecnología en Superficies y Plasma

Plasma assisted CO2 dissociation in pure and gas mixture streams with a ferroelectric packed-bed reactor in ambient conditions

Navascues, P; Cotrino, J; Gonzalez-Elipe, AR; Gomez-Ramirez, A
Chemical Engineering Journal, 430 (2022) 133066

Carbon dioxide decomposition is a challenging target to combat climate change. Nonthermal plasmas are advantageous for this purpose because they operate at ambient conditions and can be easily scaled-up. In this study, we attempt the CO2 splitting into CO and O-2 in a parallel plate packed-bed plasma reactor moderated with Lead Zirconate Titanate (PZT) as fermelectric component, achieving conversion rates and energy efficiencies higher than those obtained with BaTiO3 in our experimental device. The analysis of the reaction mechanisms with optical emission spectroscopy under various operating conditions has shown a direct correlation between energy efficiency and intensity of CO* emission bands. These results and those obtained with a LiNbO3 plate placed onto the active electrode suggest that high temperature electrons contribute to the splitting of CO2 through an enhancement in the formation of CO2+ intermediate species. Results obtained for CO2 + O-2 mixtures confirm this view and suggest that back recombination processes involving CO and O-2 may reduce the overall splitting efficiency. The study of mixtures of CO2 and dry air has proved the capacity of fermelectric packed-bed reactors to efficiently decompose CO2 with no formation of harmful NxOy subproducts in conditions close to those in real facilities. The found enhancement in energy efficiency with respect to that found for the pure gas decomposition supports that new reaction pathways involving nitrogen molecules are contributing to the dissociation reaction. We conclude that PZT moderated packed-bed plasma reactors is an optimum alternative for the decompositon of CO2 in real gas flows and ambient conditions.


Febrero, 2022 | DOI: 10.1016/j.cej.2021.133066

Nanotecnología en Superficies y Plasma

Coarse-grained approach to amorphous and anisotropic materials in kinetic Monte Carlo thin-film growth simulations: A case study of TiO2 and ZnO by plasma-enhanced chemical vapor deposition

Budagosky, J; Garcia-Casas, X; Sanchez-Valencia, JR; Barranco, A; Borras, A
Plasma Processes and Polymers (2022) e2100179

The growth of TiO2 and ZnO thin films is studied by means of coarse-grained kinetic Monte Carlo simulations under conditions typically encountered in plasma-enhanced chemical vapor deposition experiments. The basis of our approach is known to work well to simulate the growth of amorphous materials using cubic grids and is extended here to reproduce not only the morphological characteristics and scaling properties of amorphous TiO2 but also the growth of polycrystalline ZnO with a good approximation, including the evolution of the film texture during growth and its dependence on experimental conditions. The results of the simulations have been compared with available experimental data obtained by X-ray diffraction, analysis of the texture coefficients, atomic force microscopy, and scanning electron microscopy.


Enero, 2022 | DOI: 10.1002/ppap.202100179

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Compositional gradients at the nanoscale in substoichiometric thin films deposited by magnetron sputtering at oblique angles: A case study on SiOx thin films

Garcia-Valenzuela, A; Alcaide, AM; Rico, V; Ferrer, FJ; Alcala, G; Rojas, TC; Alvarez, R; González-Elipe, AR; Palmero, A
Plasma Processes and Polymers (2022) e2100116

We demonstrate the existence of stoichiometric variations at the nanoscale when growing nanocolumnar SiOx thin films by reactive magnetron sputtering deposition at oblique angles. Results show stoichiometric variations in the range 0.3 < x < 1.3 when growing a SiO0.5 thin film. This agrees with results from a numerical growth model that obtains a shift of the stoichiometry in all nanocolumns from lower values at the side facing the Si target to higher values at the opposite side. The different momentum distribution of the gaseous reactive and sputtered species results in preferential incorporation of the latter at a particular side of the nanocolumns. The general occurrence of this mechanism during the reactive magnetron sputtering deposition of substoichiometric thin films at oblique angles is discussed.


Enero, 2022 | DOI: 10.1002/ppap.202100116

Nanotecnología en Superficies y Plasma

Plasma engineering of microstructured piezo-Triboelectric hybrid nanogenerators for wide bandwidth vibration energy harvesting

Garcia-Casas, X; Ghaffarinehad, A; Aparicio, FJ; Castillo-Seoane, J; Lopez-Santos, C; Espinos, JP; Cotrino, J; Sanchez-Valencia, JR; Barranco, A; Borras, A
Nano Energy, 91 (2022) 106673

We introduce herein the advanced application of low-pressure plasma procedures for the development of piezo and triboelectric mode I hybrid nanogenerators. Thus, plasma assisted deposition and functionalization methods are presented as key enabling technologies for the nanoscale design of ZnO polycrystalline shells, the formation of conducting metallic cores in core@shell nanowires, and for the solventless surface modification of polymeric coatings and matrixes. We show how the perfluorinated chains grafting of polydimethylsiloxane (PDMS) provides a reliable approach to increase the hydrophobicity and surface charges at the same time that keeping the PDMS mechanical properties. In this way, we produce efficient Ag/ZnO convoluted piezoelectric nanogenerators supported on flexible substrates and embedded in PDMS compatible with a contact-separation triboelectric architecture. Factors like crystalline texture, ZnO thickness, nanowires aspect ratio, and surface chemical modification of the PDMS are explored to optimize the power output of the nanogenerators aimed for harvesting from low-frequency vibrations. Just by manual triggering, the hybrid device can charge a capacitor to switch on an array of color LEDs. Outstandingly, this simple three-layer architecture allows for harvesting vibration energy in a wide bandwidth, thus, we show the performance characteristics for frequencies between 1 Hz and 50 Hz and demonstrate the successful activation of the system up to ca. 800 Hz.


Enero, 2022 | DOI: 10.1016/j.nanoen.2021.106673



2021


Materiales Nanoestructurados y Microestructura

Influence of helium incorporation on growth process and properties of aluminum thin films deposited by DC magnetron sputtering

Ibrahim, S; Lahboub, FZ; Brault, P; Petit, A; Caillard, A; Millon, E; Sauvage, T; Fernandez, A; Thomann, Al
Surface & Coatings Technology, 426 (2021) 127808

The effect of helium content on the morphology, crystallinity, and composition of aluminum films was investigated by depositing He-loaded Al films onto Si substrates via direct current (DC) magnetron sputtering in different Ar/He plasma mixtures. Three different plasma regimes were identified depending on the percentage of He in the gas phase. For a low He to total gas ratio (ΓHe ≤ 70%), the plasma is dominated by argon, where Ar+ ions contribute to sputter out the target atoms. The films deposited in this regime exhibited the classical dense columnar structure and contain very low amount of He (below 2%). Then, as ΓHe increases, helium ions begin to be formed and more fast He neutrals reach the substrate, affecting the film growth. As He amount increased in the gas phase up to 95%, the proportion of He inserted in the films rised up to ⁓15 at. %. Moreover, bubbles/porosity were formed inside the films; those obtained in pure He plasma presented a highly porous fiberform nanostructure. All results confirmed that the modification of the film characteristics was related to the change of the deposition conditions when Ar was replaced by He and to the insertion/release mechanisms of He during the growth.


Noviembre, 2021 | DOI: 10.1016/j.surfcoat.2021.127808

Nanotecnología en Superficies y Plasma

Extraction of microstructural parameters from sculptured thin films nanoindentation

Gaillard, Y; Jimenez-Pique, E; Oliva-Ramirez, M; Rico, VJ; Gonzalez-Elipe, AR
Surface & Coatings Technology, 425 (2021) 127696

This work deals with the indentation analysis of nanocolumnar thin films and the difficulties encountered to deduce relevant mechanical parameters by this methodology. SiO2 thin films prepared by physical vapour oblique angle deposition with different nanocolumnar microstructures have been subjected to indentation analysis. Despite the fact that the films had been made of the same material, deposited on the same substrate and had similar thickness, their indentation responses were different and depended on their particular microstructure. It has been also realised that the measured hardness and elastic modulus variation with the indentation depth were length scale dependent and that there is not a unique analytical thin-film nanoindentation model to extract the mechanical properties from the experimental nanoindentation curves. To overcome these limitations a numerical finite element model (FEM) of the nanocolumnar coatings has been built to figure out the contributions of the different physical phenomena intervening in the indentation process. This FEM simulation relies on a description of the elasto-plastic microstructural units of the coatings and the contact friction interactions between them. Based on this simulation a parametrical representation, incorporating two length scales and the contributions of densification and/or the buckling of nanocolumnar units, has been developed to account for the evolution of the apparent elastic modulus deduced from numerical indentation tests. A Hall-Petch modification of this description considering two length scales instead of the common approximation considering a single length scale has rendered the best agreement with the elastic values determined experimentally. Although, at the present stage, the particular microstructure of the films can not be deduced from the evolution of their elastic moduli with the indentation depth, the obtained results and their interpretation constitute a first though essential step for the elaboration of an inverse analysis methodology capable of correlating microstructure and elastic response of nanocolumnar coatings.


Noviembre, 2021 | DOI: 10.1016/j.surfcoat.2021.127696

Nanotecnología en Superficies y Plasma

Recent Advances in Alkaline Exchange Membrane Water Electrolysis and Electrode Manufacturing

Lopez-Fernandez, E; Sacedon, CG; Gil-Rostra, J; Yubero, F; Gonzalez-Elipe, AR; De Lucas-Consuegra, A
Molecules, 26 (2021) 6326

Water electrolysis to obtain hydrogen in combination with intermittent renewable energy resources is an emerging sustainable alternative to fossil fuels. Among the available electrolyzer technologies, anion exchange membrane water electrolysis (AEMWE) has been paid much attention because of its advantageous behavior compared to other more traditional approaches such as solid oxide electrolyzer cells, and alkaline or proton exchange membrane water electrolyzers. Recently, very promising results have been obtained in the AEMWE technology. This review paper is focused on recent advances in membrane electrode assembly components, paying particular attention to the preparation methods for catalyst coated on gas diffusion layers, which has not been previously reported in the literature for this type of electrolyzers. The most successful methodologies utilized for the preparation of catalysts, including co-precipitation, electrodeposition, sol-gel, hydrothermal, chemical vapor deposition, atomic layer deposition, ion beam sputtering, and magnetron sputtering deposition techniques, have been detailed. Besides a description of these procedures, in this review, we also present a critical appraisal of the efficiency of the water electrolysis carried out with cells fitted with electrodes prepared with these procedures. Based on this analysis, a critical comparison of cell performance is carried out, and future prospects and expected developments of the AEMWE are discussed.


Noviembre, 2021 | DOI: 10.3390/molecules26216326

Nanotecnología en Superficies y Plasma

Mechanically Switchable Wetting Petal Effect in Self-Patterned Nanocolumnar Films on Poly(dimethylsiloxane)

Parra-Barranco, J; Lopez-Santos, C; Sanchez-Valencia, JR; Borras, A; Gonzalez-Elipe, AR; Barranco, A
Nanomaterials, 11 (2021) 2566

Switchable mechanically induced changes in the wetting behavior of surfaces are of paramount importance for advanced microfluidic, self-cleaning and biomedical applications. In this work we show that the well-known polydimethylsiloxane (PDMS) elastomer develops self-patterning when it is coated with nanostructured TiO2 films prepared by physical vapor deposition at glancing angles and subsequently subjected to a mechanical deformation. Thus, unlike the disordered wrinkled surfaces typically created by deformation of the bare elastomer, well-ordered and aligned micro-scaled grooves form on TiO2/PDMS after the first post-deposition bending or stretching event. These regularly patterned surfaces can be reversibly modified by mechanical deformation, thereby inducing a switchable and reversible wetting petal effect and the sliding of liquid droplets. When performed in a dynamic way, this mechanical actuation produces a unique capacity of liquid droplets (water and diiodomethane) transport and tweezing, this latter through their selective capture and release depending on their volume and chemical characteristics. Scanning electron and atomic force microscopy studies of the strained samples showed that a dual-scale roughness, a parallel alignment of patterned grooves and their reversible widening upon deformation, are critical factors controlling this singular sliding behavior and the possibility to tailor their response by the appropriate manufacturing of surface structures.


Octubre, 2021 | DOI: 10.3390/nano11102566

Nanotecnología en Superficies y Plasma

Plasma-Assisted Deposition of TiO2 3D Nanomembranes: Selective Wetting, Superomniphobicity, and Self-Cleaning

Montes, L; Roman, JM; Garcia-Casas, X; Castillo-Seoane, J; Sanchez-Valencia, JR; Barranco, A; Lopez-Santos, C; Borras, A
Advanced Materials Interfaces (2021) 2100767

Fabrication of tunable wetting surfaces is sought for the last years given its importance on energy, biomaterials and antimicrobials, water purification, microfluidics, and smart surfaces. Liquid management on surfaces mainly depends on the control at the micro- and nanoscale of both roughness and chemical composition. Herein, the combination of a soft-template method and plasma-enhanced chemical vapor deposition is presented for the synthesis of TiO2 nanofibers on porous substrates such as cellulose and stainless-steel membranes. The protocol, carried out under mild conditions, produces 3D nanomembranes with superhydrophobicity and oleophilicity that are tested as microliter water/oil filters. Photoactivation of TiO2 by UV illumination provides a straightforward approach for wetting tunability that converts the surface into amphiphilic. A final chemical modification of the TiO2 nanofibers by embedding them in an elastomeric polymeric shell and by fluorine-based grafting opens the path toward the formation of superomniphobic and self-cleaning surfaces with long-lasting lifetimes. Thus, a reliable procedure is demonstrated for the fabrication of TiO2 nanofibers, which allows the modification of porous supports and provides an innovative route for the development of 3D nanomembranes with under design wetting. This protocol is extendable to alternative metal oxides, metals, and core@shell nanoarchitectures with potential multifunctionalities.


Octubre, 2021 | DOI: 10.1002/admi.202100767

Nanotecnología en Superficies y Plasma

Photonic sensor systems for the identification of hydrocarbons and crude oils in static and flow conditions

Gil-Rostra, J; Quintero-Moreno, S; Rico, VJ; Yubero, F; Sanza, FJ; Casquel, R; Gallo-Valverde, E; Jara-Galan, ME; Sanz-Sanz, P; Holgado, M; Gonzalez-Elipe, AR
Sensors and Actuators B-Chemical, 344 (2021) 130265

Identification of hydrocarbons and crude oils is typically carried out with samples that, taken from natural sources or refineries, must be brought to the laboratory for their analysis with rather sophisticated instruments. Alternatively, "in situ" procedures have been also developed for this purpose. In this work, we propose the use of a series of several sensor systems based on photonic transducers in the form of chips for the identification and classification of crude oils and hydrocarbons through the determination of their refractive index in the visible and absorption in the near infrared regions of the electromagnetic spectrum. Two of the photonic transducers rely on modifications of a Bragg microcavity and they monitor the changes in visible light interference phenomena that occur in response to the variation of the refractive index of oils. The third one, in the form of a dielectric mirror, monitors the near infrared absorption of crude oils and hydrocarbons through the recording of a transflectance spectrum. The capacity of these transducers for crude oil identification is proved by the analysis of a series of oils and distilled fractions that have been properly identified and classified as a function of their density and partition of long hydrocarbon chains. The three photonic transducers are operated with optical fibers and can be used in static and dynamic modes, this latter under conditions that are especially well-suited for "insitu" analysis of oil streams in real facilities. The proved resistance of the chips to high pressure and temperature conditions supports their suitability to withstand harsh working environments as those existing in extraction wells.


Octubre, 2021 | DOI: 10.1016/j.snb.2021.130265

Tribología y Protección de Superficies

Effect of Al content on the hardness and thermal stability study of AlTiN and AlTiBN coatings deposited by HiPIMS

Mendez, A; Monclus, MA; Santiago, JA; Fernandez-Martinez, I; Rojas, TC; Garcia-Molleja, J; Avella, M; Dams, N; Panizo-Laiz, M; Molina-Aldareguia, JM
Surface & Coatings Technology, 422 (2021) 127513

The microstructure, mechanical properties and thermal stability of AT(x)Ti(1-x)N and Al1Ti1-xBN coatings grown by reactive high-power impulse magnetron sputtering (HiPIMS) have been analyzed as a function of Al/(Al + Ti) ratio (x) between 0.5 and 0.8. The coatings were predominantly formed by a face-centered cubic Ti(Al)N crystalline phase, both with and without B, even for x ratios as high as 0.6, which is higher than the ratio typically encountered for AlxTi1-xN coatings deposited by reactive magnetron sputtering. B doping, in combination with the highly energetic deposition conditions offered by HiPIMS, results in the suppression of the columnar grain morphology typically encountered in AlxTi1-xN coatings. On the contrary, the AlxTi1-xN coatings grown by HiPIMS present a dense nanocomposite type microstructure, formed by nanocrystalline Ti(Al) N domains and amorphous regions composed of Ti(Al)B 2 and BN. As a result, high-Al content (x approximate to 0.6) AlxTi1-xN coatings grown by HiPIMS offer higher hardness, elasticity and fracture toughness than AlxTi1-xN coatings. Moreover, the thermal stability and the hot hardness are substantially enhanced, delaying the onset of formation of the detrimental hexagonal AlN phase from 850 degrees C in the case of Al0.6Ti0.4N, to 1000 degrees C in the case of Al0.6Ti0.4N.


Septiembre, 2021 | DOI: 10.1016/j.surfcoat.2021.127513

Tribología y Protección de Superficies

Nb-C thin films prepared by DC-MS and HiPIMS: Synthesis, structure, and tribomechanical properties

Sala, N; Abad, MD; Sánchez-López, JC; Caro, J; Colominas, C
Surface & Coatings Technology, 422 (2021) 127569

Nanostructured Nb-C thin films were prepared by direct current magnetron sputtering (DC-MS) and high-power impulse magnetron sputtering (HiPIMS). The films were characterized in depth by X-ray diffraction (XRD), grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy, electron probe microanalysis, and Raman spectroscopy. The mechanical properties were measured by nanoindentation, and the tribological properties were measured by pin-on-disk tests in ambient air. The wear tracks and ball scars were analyzed by Raman spectroscopy to elucidate the tribochemical reactions that occurred at the contact area and to determine the wear mechanism for each specimen type. The thermal stability of the coatings was studied up to 1000 degrees C using Raman spectroscopy and XRD. The samples prepared by DC-MS were very dense, and the phase composition changed from purely nanocrystalline (Nb2C and NbC) to a mixture of NbC crystals embedded in an amorphous carbon-based matrix (NbC/a-C(:H)). However, the samples prepared by HiPIMS developed a marked columnar morphology with a NbC/a-C(:H) nanocomposite structure. The hardness values ranged from 11 to 20 GPa depending on the deposition technique and the amount of the soft a-C(:H) phase present in the sample. The tribological properties of all the coatings were remarkably good when the carbon content was approximately 50 at.%. The formation of a lubricating sp(2)-rich C tribofilm between the ball and coating during the pin-on-disk tests was observed by Raman spectroscopy. The tribofilm formed preferentially on the samples prepared by HiPIMS, which had higher C contents. At 750 degrees C, the degradation of the NbC phases resulted in the formation of an additional a-C phase and niobium oxides.


Septiembre, 2021 | DOI: 10.1016/j.surfcoat.2021.127569

Materiales Nanoestructurados y Microestructura

Pd-C Catalytic Thin Films Prepared by Magnetron Sputtering for the Decomposition of Formic Acid

Arzac, GM; Fernandez, A; Godinho, V; Hufschmidt, D; de Haro, MCJ; Medran, B; Montes, O
Nanomaterials, 11 (2021) 2326

Formic acid is an advantageous liquid organic hydrogen carrier. It is relatively nontoxic and can be synthesized by the reaction of CO2 with sustainable hydrogen or by biomass decomposition. As an alternative to more widely studied powdery catalysts, supported Pd-C catalytic thin films with controlled nanostructure and compositions were newly prepared in this work by magnetron sputtering on structured supports and tested for the formic acid decomposition reaction. A two-magnetron configuration (carbon and tailored Pd-C targets) was used to achieve a reduction in Pd consumption and high catalyst surface roughness and dispersion by increasing the carbon content. Activity and durability tests were carried out for the gas phase formic acid decomposition reaction on SiC foam monoliths coated with the Pd-C films and the effects of column width, surface roughness and thermal pre-reduction time were investigated. Activity of 5.04 mol(H2)center dot g(Pd)(-1)center dot h(-1) and 92% selectivity to the dehydrogenation reaction were achieved at 300 degrees C for the catalyst with a lower column width and higher carbon content and surface roughness. It was also found that deactivation occurs when Pd is sintered due to the elimination of carbon and/or the segregation and agglomeration of Pd upon cycling. Magnetron sputtering deposition appears as a promising and scalable route for the one-step preparation of Pd-C catalytic films by overcoming the different deposition characteristics of Pd and C with an appropriate experimental design.


Septiembre, 2021 | DOI: 10.3390/nano11092326

Nanotecnología en Superficies y Plasma

Laser-induced scanning transfer deposition of silver electrodes on glass surfaces: A green and scalable technology

Molina, R; Ertugrul, M; Larrea, A; Navarro, R; Rico, V; Yubero, F; Gonzalez-Elipe, AR: De la Fuente, GF; Angurel, LA
Applied Surface Science, 556 (2021) 149673

A pulsed laser ablation backwriting technique with high repetitive rates is implemented for the fabrication of silver coatings on glass surfaces. This method enables geometrical constraint-free deposition of metallic coatings. These exhibit sufficiently low electrical resistance to be used as electrodes in dielectric barrier discharge (DBD) plasma elements. Ambient air deposition of metallic silver electrodes on standard glass slides is explored using a sub-ns UV laser source, combined with hybrid beam scanning methods. The green nature of the overall deposition process includes a preliminary irradiation scan to homogenise the target surface before the subsequent backwriting step. Metal transfer is achieved by combining two phenomena within a simple beam scanning process: LIRT (laserinduced reverse transfer) of silver from the target to the glass, with a partial and secondary LIFT (Laser-Induced Forward Transfer) of silver from the glass to the target. Appropriate selection of pulse energy and pulse repetition rates, beam scanning velocities and target motion enable the growth of sufficiently thick Ag deposits on glass with the required low electrical resistivity and nearly 2D constraint-free geometry. This method avoids the use of vacuum and liquids, resulting in a cheap, facile and green methodology for the deposition of silver electrodes onto transparent substrate surfaces.


Agosto, 2021 | DOI: 10.1016/j.apsusc.2021.149673

Nanotecnología en Superficies y Plasma - Materiales Ópticos Multifuncionales

One-reactor vacuum and plasma synthesis of transparent conducting oxide nanotubes and nanotrees: from single wire conductivity to ultra-broadband perfect absorbers in the NIR

Castillo-Seoane, J; Gil-Rostra, J; Lopez-Flores, V; Lozano, G; Ferrer, FJ; Espinos, JP; Ostrikov, K; Yubero, F; Gonzalez-Elipe, AR; Barranco, A; Sanchez-Valencia, JR; Borras, A
Nanoscale, 13 (2021) 13882-13895

The eventual exploitation of one-dimensional nanomaterials needs the development of scalable, high yield, homogeneous and environmentally friendly methods capable of meeting the requirements for fabrication of functional nanomaterials with properties on demand. In this article, we demonstrate a vacuum and plasma one-reactor approach for the synthesis of fundamental common elements in solar energy and optoelectronics, i.e. the transparent conducting electrode but in the form of nanotube and nanotree architectures. Although the process is generic and can be used for a variety of TCOs and wide-bandgap semiconductors, we focus herein on indium doped tin oxide (ITO) as the most previously researched in previous applications. This protocol combines widely applied deposition techniques such as thermal evaporation for the formation of organic nanowires serving as 1D and 3D soft templates, deposition of polycrystalline layers by magnetron sputtering, and removal of the templates by simply annealing under mild vacuum conditions. The process variables are tuned to control the stoichiometry, morphology, and alignment of the ITO nanotubes and nanotrees. Four-probe characterization reveals the improved lateral connectivity of the ITO nanotrees and applied on individual nanotubes shows resistivities as low as 3.5 +/- 0.9 x 10(-4) omega cm, a value comparable to that of single-crystalline counterparts. The assessment of diffuse reflectance and transmittance in the UV-Vis range confirms the viability of the supported ITO nanotubes as random optical media working as strong scattering layers. Their further ability to form ITO nanotrees opens a path for practical applications as ultra-broadband absorbers in the NIR. The demonstrated low resistivity and optical properties of these ITO nanostructures open a way for their use in LEDs, IR shields, energy harvesting, nanosensors, and photoelectrochemical applications.


Agosto, 2021 | DOI: 10.1039/d1nr01937f

Nanotecnología en Superficies y Plasma

Characterizing the physicochemical and mechanical properties of ZrN thin films deposited on Zr substrates by pulsed laser technique

Ghemras, I; Abdelli-Messaci, S; Alili, B; Gonzalez-Elipe, AR; Rico, VJ; Izerrouken, M; Khereddine, AY; Hadj-Larbi, F
European Physical Journal-Applied Physics, 95 (2021) 10301

Due to their outstanding physical and mechanical features, ZrN thin films are increasingly used as coatings to protect materials intended for nuclear applications such as Zirconium. To our knowledge, there is no report of pulsed laser deposition (PLD) of ZrN thin films on a Zr substrate. In this work, we have successfully prepared ZrN thin films on Zr substrates using the PLD technique with a KrF excimer laser, in a N-2 environment at 2 Pa pressure and a fixed substrate temperature of 500 degrees C. The deposited 200 nm ZrN thin films exhibited a homogeneous surface and showed a face-centered cubic polycrystalline structure. The surface roughness was 3.69 nm. X-ray diffraction, Raman and X-ray photoelectron spectroscopy measurements confirmed the presence of ZrN. The coated sample's mean value of hardness (11.6 GP) doubled that of the uncoated sample.


Julio, 2021 | DOI: 10.1051/epjap/2021210064

Tribología y Protección de Superficies - Materiales Ópticos Multifuncionales

High-temperature solar-selective coatings based on Cr(Al)N. Part 1: Microstructure and optical properties of CrNy and Cr1-xAlxNy films prepared by DC/HiPIMS

Rojas, TC; Caro, A; Lozano, G.; Sanchez-Lopez, JC
Solar Energy Materials and Solar Cells, 223 (2021) 110951

In order to explore the potentialities of Cr1-x(Al)xNy materials in multilayer-based solar selective coatings (SSC) for high temperature applications (T > 500 °C), the optical behavior of Cr1-x(Al)xNy films is studied in this work. Two sets of layers (CrNy and Cr1-xAlxNy) were prepared by direct current (DC) and high-power impulse magnetron sputtering (HiPIMS) technology. The deposition parameters: N2 flux, HiPIMS frequency and aluminum sputtering power, were modified to get a wide variety of stoichiometries. The composition, morphology, phases and electronic structure of the films were characterized in depth. The optical behavior was determined by UV–Vis–NIR and FTIR spectroscopies, and the optical constants were obtained from the measured transmittance and reflectance spectra based on appropriate dielectric function models. Our results indicate that small changes in the layer composition influence the optical constants. In particular, a metallic-like behavior was obtained for CrNy layers with N vacancies (CrN0.95 and CrN0.67 films) while a semiconductor-like behavior was observed for CrN1.08. Thus, the CrNy films can be used as effective absorber layer in multilayer-based SSC, and namely, the CrN0.67 film as an IR reflector/absorber layer too. Likewise, the optical properties of Cr1-xAlxNy layers can also be tuned from metallic to semiconductor-like behavior depending on the chemical composition. Indeed, the absorption coefficients of Cr1-xAlxNy films with optimized Al content and N-vacancies are comparable to those reported for state-of-the-art materials such as TiAlN or TiAlCrN. In addition, a Cr0.96Al0.04N0.89 film was found to be a suitable IR reflector/absorber layer.


Mayo, 2021 | DOI: 10.1016/j.solmat.2020.110951

Nanotecnología en Superficies y Plasma

Novel procedure for studying laser-surface material interactions during scanning laser ablation cleaning processes on Cu-based alloys

Di Francia, E; Lahoz, R; Neff, D; Rico, V; Nuns, N; Angelini, E; Grassini, S
Applied Surface Science, 544 (2021) art. 178820

Laser ablation is an effective method to clean Cu-based alloys. A novel procedure of characterisation was developed involving O-18 isotopes evaluated by ToF-SIMS spectroscopy to assess the driving mechanisms of laser-surface interactions. The presence of re-oxidised compounds was detected, discerning between the oxygen from the corrosion layer and the one introduced by the interaction with the laser (that was generated in a controlled atmosphere of O-18 diluted in N-2). A set of samples treated with different laser conditions were characterised by FESEM and mu Raman. The results have shown that re-oxidation phenomenon can occur and its selectivity depends on the laser conditions.


Abril, 2021 | DOI: 10.1016/j.apsusc.2020.148820

Nanotecnología en Superficies y Plasma

Electrochromic response and porous structure of WO3 cathode layers

Louloudakis, D; Mouratis, K; Gil-Rostra, J; Koudoumas, E; Alvarez, R; Palmero, A; Gonzalez-Elipe, AR
Electrochimica Acta, 376 (2021) 138049

Maximizing the electrochromic response of tungsten oxide-based systems demands highly porous electrode layers that facilitate the incorporation of electrolyte cations during the reduction process. In this work, amorphous and porous WO3 thin films were grown on indium tin dioxide glass substrates by magnetron sputtering at oblique angles at two different plasma gas pressures. Remarkably, the film that showed higher porosity presented a worse electrochromic response in terms of durability, time response and charge density capacity. This result is analyzed and explained on the basis of the features of the porous structure of the films: While the typical nanostructure developed at low pressures possesses large and connected pore voids with few ramifications, the nanostructure generated at a higher pressure presents a rather sponge-like porous structure with numerous and small well-connected voids. A general discussion on the role of the porous structure and, particularly, on the accessible pore volume and area is carried out. It is concluded that not only the accessible pore volume, defining the volume of electrolyte that stays inside the layer, but also the accessible pore area, which defines the efficiency of the incorporation/release of Li+ cations within the electrode material, determine the efficiency and reversibility of the electrochromic response.


Abril, 2021 | DOI: 10.1016/j.electacta.2021.138049

Materiales para Bioingeniería y Regeneración Tisular

Nanofibrous Matrix of Defined Composition Sustains Human Induced Pluripotent Stem Cell Culture

Borrego-Gonzalez, S; de la Cerda, B; Diaz-Corrales, FJ; Diaz-Cuenca, A
ACS Applied Bio Materials, 4 (2021) 3035-3040

Human induced pluripotent stem cells (hiPSCs) represent the most promising biological material for regenerative medicine applications. In this work, a 3D solid nanofibrous matrix of defined composition (Colamigel-S) consisting of 97 wt % gelatin, 2.6 wt % atelocollagen, and 0.4 wt % laminin has been reproducibly processed and characterized and exhibits a homogeneous nanofibrillar network of high surface area, interconnected microcavities, and typical D-periodic collagen fibril nanostructural features. The purpose of the study was to test the performance of Colamigel-S as substrate for in vitro hiPSCs culture, finding that these cells efficiently attach and grow keeping their characteristic stem morphology and undifferentiated state.


Abril, 2021 | DOI: 10.1021/acsabm.0c00425

Nanotecnología en Superficies y Plasma

Rietveld Refinement, mu-Raman, X-ray Photoelectron, and Mossbauer Studies of Metal Oxide-Nanoparticles Growth on Multiwall Carbon Nanotubes and Graphene Oxide

Ramos-Guivar, JA; Gonzalez-Gonzalez, JC; Litterst, FJ; Passamani, EC
Crystal Growth & Design, 21 (2021) 2128-2141

Applying a modified coprecipitation method, maghemite and anatase nanoparticles embedded in graphene oxide and multiwall carbon nanotube frameworks were prepared, and a detailed structural characterization is presented. Transmission electron images have revealed that the multiwall carbon nanotubes and graphene oxide act as substrates to reduce the nanoparticle agglomeration with narrow sizes of ca. 9-20 nm, in agreement with the results of the Rietveld refinement, which have also indicated their crystallite apparent size and shapes using the spherical harmonics approach. In structural studies of maghemite nanoparticles by Raman spectroscopy, it was found that the effect of optical density and laser power intensity plays a significant role. When no optical filter was located between the powder sample and the laser source, a transformation from the gamma-Fe2O3 to the alpha-Fe2O3 phase was observed, as demonstrated by the disappearance of the characteristic broad Raman peak (A(1g)) of the gamma-Fe2O3 phase when increasing the laser power. X-ray photoelectron spectroscopy has also brought insights into the functionalization mechanism, suggesting that the one-pot reduction of the graphene oxide is favored by the alkaline gamma-Fe2O3 nanoparticle growth. The temperature dependence of the Fe-57 Mossbauer spectra has indicated that the effective anisotropy constant of Fe oxide-based nanoparticles is similar to that of bulk maghemite, and magnetic relaxation of Fe3+ spins depends on particle sizes.


Abril, 2021 | DOI: 10.1021/acs.cgd.0c01551

Nanotecnología en Superficies y Plasma

New Insights on the Conversion Reaction Mechanism in Metal Oxide Electrodes for Sodium-Ion Batteries

Mosa, J; Garcia-Garcia, FJ; Gonzalez-Elipe, AR; Aparicio, M
Nanomaterials, 11 (2021) 966

Due to the abundance and low cost of exchanged metal, sodium-ion batteries have attracted increasing research attention for the massive energy storage associated with renewable energy sources. Nickel oxide (NiO) thin films have been prepared by magnetron sputtering (MS) deposition under an oblique angle configuration (OAD) and used as electrodes for Na-ion batteries. A systematic chemical, structural and electrochemical analysis of this electrode has been carried out. The electrochemical characterization by galvanostatic charge-discharge cycling and cyclic voltammetry has revealed a certain loss of performance after the initial cycling of the battery. The conversion reaction of NiO with sodium ions during the discharge process to generate sodium oxide and Ni metal has been confirmed by X-ray photoelectron spectra (XPS) and micro-Raman analysis. Likewise, it has been determined that the charging process is not totally reversible, causing a reduction in battery capacity.


Abril, 2021 | DOI: 10.3390/nano11040966

Nanotecnología en Superficies y Plasma

Form Birefringence in Resonant Transducers for the Selective Monitoring of VOCs under Ambient Conditions

Oliva-Ramirez, Manuel; Lopez-Santos, Carmen; Berthon, Hermine; Goven, Mathilde; Portoles, Jose; Gil-Rostra, Jorge; Gonzalez-Elipe, Agustin R.; Yubero, Francisco
ACS Applied Materials & Interfaces, 13 (2021) 19148-19158

In this work, we have developed a new kind of nanocolumnar birefringent Bragg microcavity (BBM) that, tailored by oblique angle deposition, behaves as a selective transducer of volatile organic compounds (VOCs). Unlike the atomic lattice origin of birefringence in anisotropic single crystals, in the BBM, it stems from an anisotropic self-organization at the nanoscale of the voids and structural elements of the layers. The optical adsorption isotherms recorded upon exposure of these nanostructured systems to water vapor and VOCs have revealed a rich yet unexplored phenomenology linked to their optical activity that provides both capacity for vapor identification and partial pressure determination. This photonic response has been reproduced with a theoretical model accounting for the evolution of the form birefringence of the individual layers upon vapor condensation in nanopores and internanocolumnar voids. BBMs that repel water vapor but are accessible to VOCs have been also developed through grafting of their internal surfaces with perfluorooctyltriethoxysilane molecules. These nanostructured photonic systems are proposed for the development of transducers that, operating under environmental conditions, may respond specifically to VOCs without any influence by the degree of humidity of the medium.


Abril, 2021 | DOI: 10.1021/acsami.1c02499

Materiales para Bioingeniería y Regeneración Tisular

Nanofibrous Gelatin-Based Biomaterial with Improved Biomimicry Using D-Periodic Self-Assembled Atelocollagen

Borrego-Gonzalez, S; Dalby, MJ; Diaz-Cuenca, A
Biomimetics, 6 (2001) 20

Design of bioinspired materials that mimic the extracellular matrix (ECM) at the nanoscale is a challenge in tissue engineering. While nanofibrillar gelatin materials mimic chemical composition and nano-architecture of natural ECM collagen components, it lacks the characteristic D-staggered array (D-periodicity) of 67 nm, which is an important cue in terms of cell recognition and adhesion properties. In this study, a nanofibrous gelatin matrix with improved biomimicry is achieved using a formulation including a minimal content of D-periodic self-assembled atelocollagen. We suggest a processing route approach consisting of the thermally induced phase separation of the gelatin based biopolymeric mixture precursor followed by chemical-free material cross-linking. The matrix nanostructure is characterized using field emission gun scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), wide angle X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The cell culture assays indicate that incorporation of 2.6 wt.% content of D-periodic atelocollagen to the gelatin material, produces a significant increase of MC3T3-E1 mouse preosteoblast cells attachment and human mesenchymal stem cells (hMSCs) proliferation, in comparison with related bare gelatin matrices. The presented results demonstrate the achievement of an efficient route to produce a cost-effective, compositionally defined and low immunogenic “collagen-like” instructive biomaterial, based on gelatin.


Marzo, 2021 | DOI: 10.3390/biomimetics6010020

Nanotecnología en Superficies y Plasma

Solid-State Dewetting of Gold on Stochastically Periodic SiO2 Nanocolumns Prepared by Oblique Angle Deposition

Oliva-Ramirez, M; Wang, D; Flock, D; Rico, V; Gonzalez-Elipe, AR; Schaaf, P
ACS Applied Materials & Interfaces, 13 (2021) 11385-11395

Solid-state dewetting (SSD) on patterned substrates is a straightforward method for fabricating ordered arrays of metallic nanoparticles on surfaces. However, a drawback of this procedure is that the patterning of substrates usually requires time-consuming and expensive two-dimensional (2D) fabrication methods. Nanostructured thin films deposited by oblique angle deposition (OAD) present at the surface a form of stochastically arranged periodic bundles of nanocolumns that might act as a patterned template for fabricating arrays of nanoparticles by SSD. In this work, we explore this concept and investigate the effect of three different types of OAD SiO2 thin films on the SSD of Au deposited on their surface. We demonstrate that the size and spatial distribution of the particles can be tailored through the surface morphology of these OAD film substrates. It has been found that the SSD of the evaporated Au layer gives rise to a bimodal size distribution of particles. A majority of them appeared as mesoparticles with sizes.100 nm and the rest as nanoparticles with similar to 10 nm, respectively, located either on top of the nanocolumns following their lateral distribution (i.e., resulting from a patterning effect) or incorporated inside the open mesopores existing among them. Moreover, on the SiO2-OAD thin films where interconnected nanocolumnar bundles arrange in the form of discrete motifs, the patterning effect gave rise to the formation of approximately one Au mesoparticle per motif, which is one of the assets of patterned SSD. The morphological, optical (i.e., plasmon resonance), and crystalline structural characteristics of Au mesoparticles suggest that the interplay between a discontinuous nanocolumnar surface acting as a template and the poor adhesion of Au onto SiO2 are key factors for the observed template effect controlling the SSD on the surface of OAD thin films.


Marzo, 2021 | DOI: 10.1021/acsami.0c19327

Nanotecnología en Superficies y Plasma

Electrical and reaction performances of packed-bed plasma reactors moderated with ferroelectric or dielectric materials

Gomez-Ramirez, A; Alvarez, R; Navascues, P; Garcia-Garcia, FJ; Palmero, A; Cotrino, J; Gonzalez-Elipe, AR
Plasma Processes and Polymers, (2021) e2000193

The operational behavior of packed-bed plasma reactors depends on the dimension, shape, and chemical properties of the pellets used as moderators, but little information exists about the influence of their specific dielectric properties. Herein, we comparatively study the electrical behavior of a packed-bed reactor filled with pellets of either dielectric (Al2O3 and glass) or ferroelectric (BaTiO3 and lead zirconate titanate) materials. We found that plasma current was higher for ferroelectrics and presented a nonlineal dependence on voltage. Moreover, for BaTiO3, we found a drastic decrease at around its relatively low Curie temperature. Differences in electrical behavior have a direct effect on the reactor performance, as illustrated for the ammonia synthesis, demonstrating the importance of moderator material dielectric properties and their dependence on temperature.


Marzo, 2021 | DOI: 10.1002/ppap.202000193

Tribología y Protección de Superficies

Long-term low friction maintenance and wear reduction on the ventral scales in snakes

Sanchez-Lopez, JC; Schaber, CF; Gorb, SN
Materials Letters, 285 (2021) 129011

Snake skins evolved to withstand permanent friction and wear during sliding. Here, the microstructure of ventral scales of the snake Lampropeltis getula californiae was analyzed using scanning electron microscopy, and the long-term dynamic friction behavior was investigated by reciprocating sliding friction tests. A smooth epoxy resin with similar elasticity modulus and hardness was used for comparison purposes. Strong differences in frictional and wear mechanisms between the two materials were revealed in spite of similar mechanical properties. Snake skin showed a considerably lower frictional coefficient that kept stable over several thousands of sliding cycles. A reduction of the stick-slip behavior was also denoted by analyzing the variation of the friction coefficient in the forward and reverse motion influencing the wear mechanism. This frictional behavior can be explained by three different but complementary mechanisms: fibrous layered composite material of the skin with a gradient of material properties, surface microstructure, and the presence of ordered layers of lipid molecules at the skin surface.


Febrero, 2021 | DOI: 10.1016/j.matlet.2020.129011

Tribología y Protección de Superficies

Insights into the role of the layer architecture of Cr-Ti-N based coatings in long-term high temperature oxidation experiments in steam atmosphere

Mato, S; Sanchez-Lopez, JC; Barriga, J; Perez, FJ; Alcala, G
Ceramics International, 47 (2021) 4257-4266

Knowledge on hard coatings has been applied in the energy field extending their use as protecting coatings of steam power generation plants components. The role of the layer architecture of Cr-Ti-N based coatings deposited by reactive cathodic arc evaporation on P92 steel substrates was studied with the focus on their oxidation resistance at 650 degrees C in 100% steam atmosphere up to 2000 h. Characterization of the coatings was performed by gravimetry, scanning electron microscopy, electron probe microanalysis, glow discharge optical emission spectroscopy, X-ray diffraction, thermodynamic simulations using the CALPHAD method, Rockwell C indentation and nanoindentation. The layered arrangement improves the oxidation resistance of TiN under the working conditions of steam power plants, as well as the mechanical properties of CrN. The produced architectures performance under the described working conditions boosts the understanding of the processes taking place at high temperature, making possible the design of optimal coatings combining the best behavior of both nitrides for each specific application, reaching a corrosion protection at high temperature in water vapor comparable to that of CrN and a hardness and Young's modulus as high as those of TiN.


Febrero, 2021 | DOI: 10.1016/j.ceramint.2020.10.003

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Patterning and control of the nanostructure in plasma thin films with acoustic waves: mechanical vs. electrical polarization effects

García-Valenzuela, A.; Fakhouri, A.; Oliva-Ramírez, M.; Rico-Gavira, V.; Rojas, T.C.; Alvarez, R.; Menzel, S.B.; Palmero, A.; Winkler, A.; González-Elipe, A.R.
Materials Horizons, 8 (2021) 515-524

Nanostructuration and 2D patterning of thin films are common strategies to fabricate biomimetic surfaces and components for microfluidic, microelectronic or photonic applications. This work presents the fundamentals of a surface nanotechnology procedure for laterally tailoring the nanostructure and crystalline structure of thin films that are plasma deposited onto acoustically excited piezoelectric substrates. Using magnetron sputtering as plasma technique and TiO2 as case example, it is demonstrated that the deposited films depict a sub-millimetre 2D pattern that, characterized by large lateral differences in nanostructure, density (up to 50%), thickness, and physical properties between porous and dense zones, reproduces the wave features distribution of the generated acoustic waves (AW). Simulation modelling of the AW propagation and deposition experiments carried out without plasma and under alternative experimental conditions reveal that patterning is not driven by the collision of ad-species with mechanically excited lattice atoms of the substrate, but emerges from their interaction with plasma sheath ions locally accelerated by the AW-induced electrical polarization field developed at the substrate surface and growing film. The possibilities of the AW activation as a general approach for the tailored control of nanostructure, pattern size, and properties of thin films are demonstrated through the systematic variation of deposition conditions and the adjustment of AW operating parameters.


Febrero, 2021 | DOI: 10.1039/D0MH01540G

Nanotecnología en Superficies y Plasma

Active sites and optimization of mixed copper-cobalt oxide anodes for anion exchange membrane water electrolysis

Lopez-Fernandez, E; Gil-Rostra, J; Escudero, C; Villar-Garcia, IJ; Yubero, F; Consuegra, AD; Gonzalez-Elipe, AR
Journal of Power Sources, 485 (2021) 229217

The optimization of the catalysts incorporated to the electrodes for anion exchange membrane water electmlysers is a key issue to maximize their performance through the improvement of the oxygen evolution reaction (OER) yield. In this work, we show that the modification of the microstructure and the chemical properties of a mixed copper-cobalt oxide anode may contribute to increase the activity of this reaction. For this purpose, the OER has been systematically studied, either in a half cell or in a membrane electrode assembly configuration, as a function of the load and agglomeration degree of the catalysts used as electrodes, as prepared on a carbon paper support by magnetron sputtering deposition in an oblique angle configuration. Chemical analysis by X-ray absorption spectroscopy and electrochemical analysis by cyclic voltammetry and impedance spectroscopy have shown that cobalt-copper mixed oxide catalysts with a 1.8 Co/Cu atomic ratio and about one micron equivalent thickness maximizes the cell performance. The chemical, structural and microstructural factors controlling the final behaviour of these anodes and accounting for this maximization of the reaction yield are discussed on the basis of these characterization results and as a function of preparation variables of the electrodes and operating conditions of the cell.


Febrero, 2021 | DOI: 10.1016/j.jpowsour.2020.229217

Nanotecnología en Superficies y Plasma

Physicochemical surface analysis and germination at different irrigation conditions of DBD plasma‐treated wheat seeds

Molina, R; Lalueza, A; Lopez-Santos, C; Ghobeira, R; Cools, P; Morent, R; de Geyter, N; Gonzalez-Elipe, AR
Plasma Processes and Polymers, 18 (2021) e2000086

Plasma treatment is increasingly being explored as an effective presowing treatment improving seed germination. This study examines the synergetic effect of the irrigation condition and the physicochemical surface properties of wheat seeds subjected to atmospheric dielectric barrier discharge plasma activation on their water uptake and germination. Extensive surface analysis revealed a remarkably enhanced wettability of plasma-treated seeds due to the insertion of oxygen-containing functionalities on their surface. However, long plasma exposures damaged the outermost layers of the pericarp due to a pronounced oxidative etching effect. Although the seed germination capacity was not affected by the plasma treatments, short plasma exposures were shown to enhance water uptake and accelerate seed germination, especially under water-scarcity conditions.


Enero, 2021 | DOI: 10.1002/ppap.202000086

Nanotecnología en Superficies y Plasma

Anisotropic Resistivity Surfaces Produced in ITO Films by Laser-Induced Nanoscale Self-organization

Lopez-Santos, C; Puerto, D; Siegel, J; Macias-Montero, M; Florian, C; Gil-Rostra, J; Lopez-Flores, V; Borras, A; Gonzalez-Elipe, AR; Solis, J
Advanced Optical Materials, 9 (2021) 2001086

Highly anisotropic resistivity surfaces are produced in indium tin oxide (ITO) films by nanoscale self-organization upon irradiation with a fs-laser beam operating at 1030 nm. Anisotropy is caused by the formation of laser-induced periodic surface structures (LIPSS) extended over cm-sized regions. Two types of optimized structures are observed. At high fluence, nearly complete ablation at the valleys of the LIPSS and strong ablation at their ridges lead to an insulating structure in the direction transverse to the LIPSS and conductive in the longitudinal one. A strong diminution of In content in the remaining material is then observed, leading to a longitudinal resistivity rho(L) approximate to 1.0 omega center dot cm. At a lower fluence, the material at the LIPSS ridges remains essentially unmodified while partial ablation is observed at the valleys. The structures show a longitudinal conductivity two times higher than the transverse one, and a resistivity similar to that of the pristine ITO film (rho approximate to 5 x 10(-4) omega center dot cm). A thorough characterization of these transparent structures is presented and discussed. The compositional changes induced as laser pulses accumulate, condition the LIPSS evolution and thus the result of the structuring process. Strategies to further improve the achieved anisotropic resistivity results are also provided.


Enero, 2021 | DOI: 10.1002/adom.202001086

Materiales para Bioingeniería y Regeneración Tisular

Sponge-like processed D-periodic self-assembled atelocollagen supports bone formation in vivo

Borrego-Gonzalez, S; Rico-Llanos, G; Becerra, J; Diaz-Cuenca, A; Visser, R
Materials Science & Engineering C-Materials for Biological Applications, 120 (2021) art.111679

Fibrous biopolymeric collagen extracted from animal tissues has been widely used for fabricating matrices for bone tissue engineering (BTE). However, animal extracted collagens can trigger immune reactions when implanted in vivo and the presence of native crosslinks leads to batch-to-batch variability. Atelocollagen, a monomeric form of collagen, is free of telopeptides, which are mainly responsible for the immunogenicity of collagen, and can self-assemble in vitro to obtain fibrils with the characteristic D-periodic staining pattern of native collagen. However, atelocollagen-based biomaterials have not extensively been studied and, hence, their suitability for BTE remains relatively unexplored. Besides, to stabilize collagen biomaterials, chemical and physical crosslinking are used, although chemical agents are cytotoxic while the physical methods yield a less effective crosslinking. A combination of physical and chemical crosslinking is a suitable alternative that has rarely been tested in BTE programs. In this work, a sponge-like biomaterial (DCol-S) was processed from D-periodic self-assembled atelocollagen and its stabilization was studied using the combination of a dehydrothermal treatment (DHT) and minimal glutaraldehyde (GTA) exposition crosslinking, to increase the resistance to degradation of the scaffold without a major effect on the biomaterial structure. The microstructural features of the final sponges were characterised and compared to a commercial biomaterial processed from native bovine collagen (Helistat (R), Integra Lifesciences, NJ, USA), demonstrating that a D-periodic nanostructure was obtained and maintained after processing of the sponges. MC3T3-E1 preosteoblast adhesion, proliferation and differentiation assays in vitro showed that DCol-S is biocompatible. Furthermore, intramuscular implantation of the biomaterials loaded with rhBMP-2 revealed that the double-crosslinked sponges were able to support ectopic bone formation, while sponges stabilised only with the DHT treatment were not. Altogether, these findings show that atelocollagen-based sponges stabilised with a DHT treatment followed by a mild GTA crosslinking are a suitable alternative to polymeric extracted collagen for BTE applications.


Enero, 2021 | DOI: 10.1016/j.msec.2020.111679



2020


Nanotecnología en Superficies y Plasma

Robust anti-icing superhydrophobic aluminum alloy surfaces by grafting fluorocarbon molecular chains

Rico, V; Mora, J; Garcia, P; Aguero, A; Borras, A; Gonzalez-Elipe, AR; Lopez-Santos, C
Applied Materials Today, 21 (2020) 100815

Infusion of low surface tension liquids in nanostructured surfaces is currently used to promote an anti icing response, although the long term stability of these systems is often jeopardized by losses of the infused liquid. In this work, we propose an alternative to the infusion procedure to induce a more effective and long lasting anti-icing capacity. The method consists of a combination of surface nanostructuration with the chemical grafting of fluorocarbon molecules. Al6061 substrates have been subjected to laser roughening and further modified with a nanostructured Al2O3 thin film to achieve a dual roughness and porous surface state. These surfaces have been subjected to a grafting treatment with perfluorooctyltriethoxysilane (PFOTES) vapor or, for comparative purposes, infused with a low surface tension liquid. A comparative analysis of the wetting, water condensation and anti-icing properties of these two systems showed an outstandingly better performance for the grafted surfaces with respect to the infused ones. Grafted surfaces were markedly superhydrophobic and required higher water vapor pressures to induce condensation. When looking for their anti-icing capacity, they presented quite long freezing delay times for supercooled water droplets (i.e. almost four hours) and exhibited a notably low ice accretion in a wind tunnel test. The high aging resistance and durability of these grafted surfaces and the reproducibility of the results obtained when subjected to successive ice accretion cycles show that molecular grafting is an efficient anti-icing methodology that, in aggressive media, may outperform the classical infusion procedures. The role of the fluorocarbon chains anchored on the surface in inducing an anti-icing functionality is discussed.


Diciembre, 2020 | DOI: 10.1016/j.apmt.2020.100815

Nanotecnología en Superficies y Plasma

Thin film electroluminescent device based on magnetron sputtered Tb doped ZnGa2O4 layers

Gil-Rostra, J; Valencia, FY; Gonzalez-Elipe, AR
Journal of Luminescence, 228 (2020) 117617

Photoluminescent (PL) layers and electroluminescent (EL) systems prepared by different methods have been systematically studied for the fabrication of flat panel displays, monitoring screens, and lighting systems. In this work we report about a new procedure of preparing Tb doped ZnGa2O4 green luminescent thin films at low temperature that consists of the simultaneous reactive magnetron sputtering (R-MS) deposition of a Zn-Ga mixed oxide acting as a matrix and the plasma decomposition (PD) of evaporated terbium acetylacetonate. The resulting films were transparent and presented a high PL efficiency making them good candidates for EL applications. Layers of this phosphor film with thickness in the order of hundreds nanometers were sandwiched between two dielectric layers of Y2O3 and AlSiNxOy that were also prepared by R-MS. The response of the resulting EL device was characterized as a function of the applied voltage and the type of AC excitation signal. The high luminance and long-term stability of these thin film electroluminescent devices (TFELDs) proves the reliability and efficiency of this kind of transparent R-MS multilayer system (with a total thickness in order of 650 nm) for display and lighting applications.


Diciembre, 2020 | DOI: 10.1016/j.jlumin.2020.117617

Tribología y Protección de Superficies

High-temperature solar-selective coatings based on Cr(Al)N. Part 2: Design, spectral properties and thermal stability of multilayer stacks

Rojas, TC; Caro, A; Escobar-Galindo, R; Sanchez-Lopez, JC
Solar Energy Materials and Solar Cells, 218 (2020) 110812

Two multilayer solar selective absorber coatings [Al/CrN0.95/Cr0.96Al0.04N1.08/Cr0.53Al0.47N1.12/Al2O3 (stack #1) and Cr0.96Al0.04N0.89/Cr0.62Al0.38N1.00/Cr0.53Al0.47N1.12/Al2O3 (stack #2)] were deposited on 316L steel by combining direct current (DC) and high power impulse magnetron sputtering (HiPIMS) technologies with the aim of increasing the working limit temperature. The composition and thickness of the constituent layers were optimized using CODE software to achieve a high solar absorptance (alpha) and low values of thermal emittance (epsilon) in the infrared region. The deposited multilayered stacks were heated during 2 h in air at 600, 700 and 800 degrees C to study their thermal stability and optical performance. Compositional, structural and optical characterization of the stacks (as-prepared and after thermal treatment) was performed. Both stacks presented a good solar selectivity with alpha > 95% and epsilon < 15%, were stable up to 600 degrees C and fulfilled the performance criterion PC < 5% after 600 and 700 degrees C treatments. Despite the stacks suffered chemical transformations above 600 degrees C, partial oxidation (stack #1) and Cr2N formation (stack #1 and #2), the optical properties were optimum up to 700 degrees C for stack #1 (alpha = 94%, epsilon((25 degrees C)) = 12%) and 600 degrees C for stack #2 (alpha = 93%, epsilon((25 degrees C)) = 13%). The solar-to-mechanical energy conversion efficiencies (eta) of the as-deposited and annealed (600 and 700 degrees C) samples were up to 20% points higher than the absorber paint commercially used (Pyromark). At 800 degrees C, they underwent a further structural transformation, provoked by the oxidation of the inner layers, and they consequently lost their solar selectivity.


Diciembre, 2020 | DOI: 10.1016/j.solmat.2020.110812

Nanotecnología en Superficies y Plasma

Wetting and spreading of liquid lithium onto nanocolumnar tungsten coatings tailored through the topography of stainless steel substrates

Munoz-Pina, S; Garcia-Valenzuela, A; Oyarzabal, E; Gil-Rostra, J; Rico, V; Alcala, G; Alvarez, R; Tabares, FL; Palmero, A; Gonzalez-Elipe, AR
Nuclear Fusion, 60 (2020) 126033

The use of liquid metal as an alternative to cover the plasma-exposed areas of fusion reactors has called for the development of substrates where refilling and metal spreading occur readily and at reasonably low temperatures. In the search for common materials for this purpose, we show that nanostructured tungsten coatings deposited on stainless steel (SS) by magnetron sputtering at oblique angles (MS-OAD) is a good option, provided that the surface microstructure of substrate is properly engineered. Tungsten thin films with nominal thicknesses of 500 and 2500 nm were deposited onto SS plates subjected to conventional surface finishing treatments (sand blasting, sand paper abrasion and electrochemical polishing) to modify the surface topography and induce the appearance of different groove patterns. In the first part of this work we show how the topographical features of the SS substrates affect the typical nanocolumnar microstructure of OAD thin films of tungsten. Subsequently, we characterize the spreading behavior of liquid lithium onto these tungsten nanocolumnar surfaces and critically discuss whether nanocolumnar tungsten thin films are a suitable option for the wetting and spreading of molten lithium. As a result, we reveal that the features of the tungsten nanocolumnar coating, characterized by a given height and void spaces between nanocolumns in the order of 1–2 μm, is critical for the spreading of molten lithium, while the existence of wider channels affects it very weakly. Moreover, it is shown that tungsten films deposited by MS-OAD on SS substrates subjected to conventional finishing procedures represent a good alternative to other more complex surface engineering procedures utilized for this purpose.


Diciembre, 2020 | DOI: 10.1088/1741-4326/abb53e

Nanotecnología en Superficies y Plasma

Thermo-optic response of MEH-PPV films incorporated to monolithic Fabry-Perot microresonators

Rostra, JG; Soler-Carracedo, K; Martin, LL; Lahoz, F; Yubero, F
Dyes and Pigments, 182 (2020) 108625

Poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) is a semiconducting optically active polymer widely used in optoelectronics research. MEH-PPV can be commercially acquired in a large range of molecular weights. However, the influence of this property on the optical performance of the polymer is often disregarded. In this paper, the thermal dependence of the refractive index of MEH-PPV thin films prepared from high and medium molecular weight polymers is investigated. Thus, monolithic Fabry-Perot (FP) microcavities are fabricated, in which the active polymer film is part of their defect layer. It is found that when these devices are used as optical temperature sensors, the position of the emission band of the microcavities excited with a blue diode laser shifts to lower wavelengths when temperature increases with sensitivities in the 0.2-0.3 nm/degrees C range. This effect is ascribed to the variation in the refractive index of the polymer active layer within the resonator with temperature. According to theoretical simulations of optical transmittance by classical transfer matrix method and the evaluation of the optical eigenmodes by finite element methods of the manufactured FP resonator cavities, it is found that the MEH-PPV films present negative thermo-optic coefficients of about-0.018 K-1 and-0.0022 K-1 for high and medium molecular weight polymers, respectively, in the temperature range between 20 and 60 degrees C. These values are about the highest reported so far, to the best of our knowledge, and points to high performance thermal sensor applications.


Noviembre, 2020 | DOI: 10.1016/j.dyepig.2020.108625

Materiales Nanoestructurados y Microestructura

Advances in the implementation of PVD-based techniques for the preparation of metal catalysts for the hydrolysis of sodium borohydride

Arzac, GM; Fernandez, A
International Journal of Hydrogen Energy, 58 (2020) 33288-33309

Sodium borohydride constitutes a safe alternative for the storage of hydrogen with a high gravimetric content. Catalytic hydrolysis of sodium borohydride permits on-demand hydrogen generation for multiple applications. In this field, the rational design of efficient metal catalysts deposited on structured supports is highly desirable. For most reactions, chemical methods are the most commonly used methods for the preparation of supported metal catalysts. Physical vapour deposition techniques are emerging as an alternative for the preparation of catalytic materials because of their multiple advantages. They permit the one-step deposition of catalysts on structured supports with controlled microstructure and composition, avoiding the multi-step procedures and the generation of hazardous by-products associated with chemical routes.

In this short review, we will describe the available literature on the application of physical vapour deposition techniques for the preparation of supported metal catalysts for the hydrolysis of sodium borohydride. The effects of the deposition parameters on the properties of the catalytic materials will be discussed, and strategies for further improvement will be proposed. Here, we also present our new results on the study of nanoporous Pt catalysts that are prepared through the chemical dealloying of magnetron sputtered Pt-Cu thin films for the hydrolysis of sodium borohydride. We discuss the capabilities of the technique to tune the microstructure from columnar to closed porous microstructures, which, coupled with dealloying, produces more active supported catalysts with lower noble metal loading. At the end, we briefly mention the application of PVD for the preparation of supported catalysts for the hydrolysis of ammonia borane, another hydrogen generating reaction of high interest nowadays.


Noviembre, 2020 | DOI: 10.1016/j.ijhydene.2020.09.041

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Plasma-Enabled Amorphous TiO2 Nanotubes as Hydrophobic Support for Molecular Sensing by SERS

Filippin, N; Castillo-Seoane, J; Lopez-Santos, MC; Rojas, CT; Ostrikov, K; Barranco, A; Sanchez-Valencia, JR; Borras, A
ACS Applied Materials & Interfaces, 12 (2020) 50721-50733

We devise a unique heteronanostructure array to overcome a persistent issue of simultaneously utilizing the surface-enhanced Raman scattering, inexpensive, Earth-abundant materials, large surface areas, and multifunctionality to demonstrate near single-molecule detection. Room-temperature plasma-enhanced chemical vapor deposition and thermal evaporation provide high-density arrays of vertical TiO2 nanotubes decorated with Ag nanoparticles. The role of the TiO2 nanotubes is 3-fold: (i) providing a high surface area for the homogeneous distribution of supported Ag nanoparticles, (ii) increasing the water contact angle to achieve superhydrophobic limits, and (iii) enhancing the Raman signal by synergizing the localized electromagnetic field enhancement (Ag plasmons) and charge transfer chemical enhancement mechanisms (amorphous TiO2) and by increasing the light scattering because of the formation of vertically aligned nanoarchitectures. As a result, we reach a Raman enhancement factor of up to 9.4 × 107, satisfying the key practical device requirements. The enhancement mechanism is optimized through the interplay of the optimum microstructure, nanotube/shell thickness, Ag nanoparticles size distribution, and density. Vertically aligned amorphous TiO2 nanotubes decorated with Ag nanoparticles with a mean diameter of 10–12 nm provide enough sensitivity for near-instant concentration analysis with an ultralow few-molecule detection limit of 10–12 M (Rh6G in water) and the possibility to scale up device fabrication.


Noviembre, 2020 | DOI: 10.1021/acsami.0c14087

Tribología y Protección de Superficies

Tailoring CrNx stoichiometry and functionality by means of reactive HiPIMS

Sanchez-Lopez, JC; Caro, A; Alcala, G; Rojas, TC
Surface & Coatings Technology, 401 (2020) 126235

This work presents a complete study of the influence of HiPIMS pulse characteristics on the microstructure, chemical composition, mechanical and oxidation resistance properties of CrN thin films. The investigated parameters were frequency and pulse length at two different nitrogen fluxes, maintaining constant the duty cycle conditions (2%). The effect of a negative bias of 100 V was investigated in a particular case. By changing the synthesis conditions, it was possible to tailor the N/Cr ratio and thus to control the CrNx stoichiometry from x = 0.63 to 1.10. The selection of longer pulses (shorter frequencies) generates more disordered structures with lower N/Cr ratios. This is reflected in higher hardness and elastic modulus values on despite of a lower oxidation resistance due to existence of larger concentration of N vacancies. The best oxidation resistance is obtained at the highest peak current combined with additional ion bombardment provided by substrate biasing. The present results open the possibilities of modifying chemical composition and engineering surfaces by changing exclusively the pulse conditions in HiPIMS deposition processes.


Noviembre, 2020 | DOI: 10.1016/j.surfcoat.2020.126235

Tribología y Protección de Superficies

Tribological performance of Nb-C thin films prepared by DC and HiPIMS

Sala, N; Abad, MD; Sanchez-Lopez, JC; Cruz, M; Caro, J; Colominas, C
Materials Letters, 277 (2020) 12834

Nanostructured NbC thin films with variable contents of Nb and C were prepared by direct current (DC) magnetron sputtering, and for the first time, via high power impulse magnetron sputtering (HiPIMS) searching for an improvement in the tribological properties. X-ray diffraction shows that increasing the carbon incorporation, the crystalline composition evolves from Nb2C to NbC phase. Further carbon enrichment leads to a nanocomposite structure formed by small NbC crystals (8-14 nm) dispersed in a-C matrix. The friction coefficient varied from high friction (0.8) to low friction (0.25) and the hardness values between 20 and 11 GPa depending on the film composition. A densification of the coatings by changing the methodology from DC to HiPIMS was not observed. 


Octubre, 2020 | DOI: 10.1016/j.matlet.2020.128334

Nanotecnología en Superficies y Plasma

Unraveling Discharge and Surface Mechanisms in Plasma-Assisted Ammonia Reactions

Navascues, P; Obrero-Perez, JM; Cotrino, J; Gonzalez-Elipe, AR; Gomez-Ramirez, A
ACS Sustainable Chemistry & Engineering, 8 (2020) 14855-14866

Current studies on ammonia synthesis by means of atmospheric pressure plasmas respond to the urgent need of developing less environmentally aggressive processes than the conventional Haber-Bosch catalytic reaction. Herein, we systematically study the plasma synthesis of ammonia and the much less investigated reverse reaction (decomposition of ammonia into nitrogen and hydrogen). Besides analyzing the efficiency of both processes in a packed-bed plasma reactor, we apply an isotope-exchange approach (using D-2 instead of H-2) to study the reaction mechanisms. Isotope labeling has been rarely applied to investigate atmospheric plasma reactions, and we demonstrate that this methodology may provide unique information about intermediate reactions that, consuming energy and diminishing the process efficiency, do not effectively contribute to the overall synthesis/decomposition of ammonia. In addition, the same methodology has demonstrated the active participation of the interelectrode material surface in the plasma-activated synthesis/decomposition of ammonia. These results about the involvement of surface reactions in packed-bed plasma processes, complemented with data obtained by optical emission spectroscopy analysis of the plasma phase, have evidenced the occurrence of inefficient intermediate reaction mechanisms that limit the efficiency and shown that the rate-limiting step for the ammonia synthesis and decomposition reactions are the formation of NH* species in the plasma phase and the electron impact dissociation of the molecule, respectively.


Octubre, 2020 | DOI: 10.1021/acssuschemeng.0c04461

Materiales Nanoestructurados y Microestructura

Tailoring materials by high-energy ball milling: TiO2 mixtures for catalyst support application

Rinaudo, MG; Beltran, AM; Fernandez, MA; Cadus, LE; Morales, MR
Materials Today Chemistry, 17 (2020) 100340

We carried out a rational design of catalyst supports by high-energy ball milling. Tailored mixtures of TiO2 crystalline phases were obtained using rotational speed and milling time as variable parameters. Polymorphic transformation from anatase to rutile through high-pressure TiO2 (II) as intermediate was confirmed by X-ray Diffraction (XRD), Raman Spectroscopy and Transmission Electron Microscopy (TEM). Also, starting material doubled its specific surface area due to particle fragmentation, as confirmed by surface area of Brunauer-Emmet-Teller (S-BET) and Scanning Electron Microscopy (SEM). Defects introduced during milling process generated oxygen vacancies in the surface and bulk of supports, as evidenced by X-ray Photoelectron Spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR). Furthermore, longer milling time increased reducibility and oxygen mobility of supports, as observed by H-2 Temperature Programmed Reduction (H-2-TPR) and O-2 Temperature Programmed Desorption (O-2-TPD). Phase composition remained unchanged even under extreme conditions, highlighting the stability of unusual TiO2 (II) phase. Properties achieved in present materials could benefit metal-support interactions and play a major role in supported catalysts. 


Septiembre, 2020 | DOI: 10.1016/j.mtchem.2020.100340

Nanotecnología en Superficies y Plasma

The wrinkling concept applied to plasma-deposited polymer-like thin films: A promising method for the fabrication of flexible electrodes

Thiry, Damien; Vinx, Nathan; Damman, Pascal; Aparicio, Francisco F.J.; Tessier, Pierre-Yves; Moerman, David; Leclere, Philippe; Godfroid, Thomas; Deprez, Sylvain; Snyders, Rony
Plasma Processes and Polymers, 17 (2020) e2000119

In this communication, we report on an innovative solvent-free method that allows for the design of nano-/micropatterns with tuneable dimensions. Our approach is based on the spontaneous wrinkling phenomenon taking place in a bilayer system formed by a mechanically responsive bottom plasma polymer layer and a top aluminum thin film. The dimensions of the wrinkles can be adjusted in a wide range (i.e., from nanometer to micrometer range) by modulating the cross-linking density as well as the thickness of the plasma polymer layer. Finally, it is demonstrated that these wrinkled surfaces could efficiently be used as flexible electrodes. The whole set of our data unambiguously reveals the attractiveness of our method for the fabrication of the micro-/nanopattern with dimensions on demand.


Septiembre, 2020 | DOI: 10.1002/ppap.202000119

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Supported Porous Nanostructures Developed by Plasma Processing of Metal Phthalocyanines and Porphyrins

Obrero, JM; Filippin, AN; Alcaire, M; Sanchez-Valencia, JR; Jacob, M; Matei, C; Aparicio, FJ; Macias-Montero, M; Rojas, TC; Espinos, JP; Saghi, Z; Barranco, A; Borras, A
Frontiers in Chemistry, 8 (2020) 520

The large area scalable fabrication of supported porous metal and metal oxide nanomaterials is acknowledged as one of the greatest challenges for their eventual implementation in on-device applications. In this work, we will present a comprehensive revision and the latest results regarding the pioneering use of commercially available metal phthalocyanines and porphyrins as solid precursors for the plasma-assisted deposition of porous metal and metal oxide films and three-dimensional nanostructures (hierarchical nanowires and nanotubes). The most advanced features of this method relay on its ample general character from the point of view of the porous material composition and microstructure, mild deposition and processing temperature and energy constrictions and, finally, its straightforward compatibility with the direct deposition of the porous nanomaterials on processable substrates and device-architectures. Thus, taking advantage of the variety in the composition of commercially available metal porphyrins and phthalocyanines, we present the development of metal and metal oxides layers including Pt, CuO, Fe2O3, TiO2, and ZnO with morphologies ranging from nanoparticles to nanocolumnar films. In addition, we combine this method with the fabrication by low-pressure vapor transport of single-crystalline organic nanowires for the formation of hierarchical hybrid organic@metal/metal-oxide and @metal/metal-oxide nanotubes. We carry out a thorough characterization of the films and nanowires using SEM, TEM, FIB 3D, and electron tomography. The latest two techniques are revealed as critical for the elucidation of the inner porosity of the layers.


Junio, 2020 | DOI: 10.3389/fchem.2020.00520

Nanotecnología en Superficies y Plasma

Chemistry and Electrocatalytic Activity of Nanostructured Nickel Electrodes for Water Electrolysis

Lopez-Fernandez, E; Gil-Rostra, J; Espinos, JP; Gonzalez-Elipe, AR; Consuegra, AD; Yubero, F
ACS Catalysis, 10 (2020) 6159-6170

Herein we have developed nanostructured nickel-based electrode films for anion exchange membrane water electrolysis (AEMWE). The electrodes were prepared by magnetron sputtering (MS) in an oblique angle configuration and under various conditions aimed at preparing metallic, oxide, or oxyhydroxide films. Their electrochemical analysis has been complemented with a thorough physicochemical characterization to determine the effect of microstructure, chemical state, bilayer structure, and film thickness on the oxygen evolution reaction (OER). The maximum electrocatalytic activity was found for the metallic electrode, where analysis by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) demonstrated that the active catalytic phase at the surface after its electrochemical conditioning is a kind of oxidized nickel oxide/hydroxide layer with the thickness of a few nanometers. Electrochemical impedance spectroscopy analysis of these steady-state working electrodes supports that the enhanced performance of the metallic nickel anode vs other chemical states resides in the easier electron transfer through the electrode films and the various interlayers built up during their fabrication and activation. The long-term steady-state operation of the anodes and their efficiency for water splitting was proved in a full-cell AEMWE setup incorporating magnetron-sputtered metallic nickel as the cathode. This work proves that MS is a suitable technique to prepare active, stable, and low-cost electrodes for AEMWE and the capacity of this technique to control the chemical state of the electrocatalytically active layers involved in the OER.


Junio, 2020 | DOI: 10.1021/acscatal.0c00856

Nanotecnología en Superficies y Plasma

Optical properties of molybdenum in the ultraviolet and extreme ultraviolet by reflection electron energy loss spectroscopy

Pauly, N; Yubero, F; Tougaard, S
Applied Optics, 59 (2020) 4527-4532

Optical properties of polycrystalline molybdenum are determined from ultraviolet up to extreme ultraviolet by reflection electron energy loss spectroscopy (REELS). Calculations are performed within the dielectric response theory by means of the quantitative analysis of electron energy losses at surfaces QUEELS-epsilon (k, omega)-REELS software [Surf. Interface Anal. 36, 824 (2004)] that allows the simulation of inelastic scattering cross sections, using a parametric energy loss function describing the optical response of the material. From this energy loss function, the real and imaginary parts of the dielectric function, the refractive index, and the extinction coefficient are deduced and compared with previously published results.


Mayo, 2020 | DOI: 10.1364/AO.391014

Nanotecnología en Superficies y Plasma

A 4-view imaging to reveal microstructural differences in obliquely sputter-deposited tungsten films

El Beainou, R; Garcia-Valenzuela, A; Raschetti, M; Cote, JM; Alvarez, R; Palmero, A; Potin, V; Martin, N
Materials Letters, 264 (2020) 127381

We report on the morphological disparity of the columnar growth in W thin films sputter-deposited by oblique angle deposition. Oriented tungsten thin films (400 +/- 50 nm thick) are prepared using a tilt angle alpha of 80 degrees and a sputtering pressure of 0.25 Pa. Inclined columns (beta = 38 +/- 2 degrees) are produced and the microstructure is observed by scanning electron microscopy. A 4-view imaging is performed in order to show inhomogeneous growing evolutions in the columns. Morphological features vs. viewing direction are also investigated from a growth simulation of these tilted W columns. Experimental and theoretical approaches are successfully compared and allow understanding how the direction of the W particle flux leads to dense or fibrous morphologies, as the column apexes are in front of the flux or in the shadowing zone. 


Abril, 2020 | DOI: 10.1016/j.matlet.2020.127381

Nanotecnología en Superficies y Plasma

Study of the influence of the precursors on the sensing properties of ZnO:Cu system

Ramos, A; Urbieta, A; Escalante, G; Hidalgo, P; Espinos, JP; Fernandez, P
Ceramics International, 46 (2020) 8358-8367

The properties of ZnO based materials for ethanol detection have been studied. Cu doped samples obtained from different precursors have been investigated. ZnO and ZnS have been used as host and Cu and CuO as dopant sources.

The sensing measurements have been mostly performed at room temperature. To monitor the effect of the presence of gas, resistivity and photoluminescence experiments with and without sensing gas have been carried out. The sensing behaviour is affected by the nature of the precursors used. For ZnO:Cu and ZnO:CuO series, a higher sensitivity is obtained at the lower gas concentrations, the better response is obtained for the sample ZnO:Cu with wt.1% of metallic copper. Strong segregation effects observed in these samples could be deleterious for the sensing properties. In the series ZnS:CuO, no segregation is observed, however the sensing behaviour is erratic and attributed to the reduction of Cu ions to the metallic state.


Abril, 2020 | DOI: 10.1016/j.ceramint.2019.12.068

Materiales para Bioingeniería y Regeneración Tisular

A Microstructure Insight of MTA Repair HP of Rapid Setting Capacity and Bioactive Response

Jimenez-Sanchez, MC; Segura-Egea, JJ; Diaz-Cuenca, A
Materials, 13 (2020) 1641

Mineral trioxide aggregate (MTA) is considered a bioactive endodontic material, which promotes natural mineralization at the material-tooth tissue interface. MTA Repair HP stands out because of the short setting time and the quick and effective bioactive response in vitro. The bioactivity, depens on material composition and microstructure. This work is devoted to analyze MTA Repair HP microstructural features, of both the powder precursor and set material, to get insights into the material physicochemical parameters-functionality performance relationships. Transmission electron microscopy (TEM), and field emission gun scanning electron microscopy (FEG-SEM) coupled with energy-dispersive X-ray (EDX) analyses were performed. X-ray diffraction (XRD) measurements were carried out at different times to investigate setting process. Bioactivity evaluation in vitro was carried out by soaking the processed cement disk in simulated body fluid (SBF). The presented results point out those MTA Repair HP precursor material characteristics of tricalcium silicate particles of nanometric size and high aspect ratio, which provide an elevated surface area and maximized components dispersion of calcium silicate and very reactive calcium aluminate. The MTA Repair HP precursor powder nanostructure and formulation, allows a hydration process comprising silicate hydrate structures, which are very effective to achieve both fast setting and efficient bioactive response.


Abril, 2020 | DOI: 10.3390/ma13071641

Nanotecnología en Superficies y Plasma

In Vitro and In Vivo Study of Titanium Grade IV and Titanium Grade V Implants with Different Surface Treatments

Diaz-Sanchez, RM; de-Paz-Carrion, A; Serrera-Figallo, MA; Torres-Lagares, D; Barranco, A; Leon-Ramos, JR; Gutierrez-Perez, JL
Metals, 10 (2020) 449

The aim of our study is to evaluate different implant surface treatments using TiIV and TiV in in vitro and in vivo studies. An in vitro study was established comprising four study groups with treated and untreated TiIV titanium discs (TiIVT and TiIVNT) and treated and untreated TiV titanium discs (TiVT and TiVNT). The surface treatment consisted in a grit blasting treatment with alumina and double acid passivation to modify surface roughness. The surface chemical composition and the surface microstructure of the samples were analyzed. The titanium discs were subjected to cell cultures to determine cell adhesion and proliferation of osteoblasts on them. The in vivo study was carried out on the tibia of three New Zealand rabbits in which 18 implants divided into three experimental groups were placed (TiIVT, TiIVNT, and TiVT). Micro-computed tomography (micro-CT) was performed to determine bone density around the implants. The results showed that cell culture had minor adhesion and cell proliferation in TiIVT and TiVT within the first 6 and 24 h. However, no differences were found after 48 h. No statistically significant differences were found in the in vivo micro-CT and histological study; however, there was a positive trend in bone formation in the groups with a treated surface. Conclusions: All groups showed a similar response to in vitro cell proliferation cultures after 48 h. No statistically significant differences were found in the in vivo micro-CT and histological study


Abril, 2020 | DOI: 10.3390/met10040449

Nanotecnología en Superficies y Plasma

Advanced Strategies in Thin Films Engineering by Magnetron Sputtering

Palmero, A; Martin, N
Coatings, 10 (2020) 419

This Special Issue contains a series of reviews and papers representing some recent results and some exciting perspectives focused on advanced strategies in thin films growth, thin films engineering by magnetron sputtering and related techniques. Innovative fundamental and applied research studies are then reported, emphasizing correlations between structuration process parameters, new ideas and approaches for thin films engineering and resulting properties of as-deposited coatings.


Abril, 2020 | DOI: 10.3390/coatings10040419

Nanotecnología en Superficies y Plasma

Positron annihilation analysis of nanopores and growth mechanism of oblique angle evaporated TiO2 and SiO2 thin films and multilayers

Garcia-Valenzuela, A; Butterling, M; Liedke, MO; Hirschmann, E; Trinh, TT; Attallah, AG; Wagner, A; Alvarez, R; Gil-Rostra, J; Rico, V; Palmero, A; Gonzalez-Elipe, AR
Microporous and Mesoporous Materials, 295 (2020) 109968

The nano-porosity embedded into the tilted and separated nanocolumns characteristic of the microstructure of evaporated thin films at oblique angles has been critically assessed by various variants of the positron annihilation spectroscopy. This technique represents a powerful tool for the analysis of porosity, defects and internal interfaces of materials, and has been applied to different as-deposited SiO2 and TiO2 thin films as well as SiO2/TiO2 multilayers prepared by electron beam evaporation at 70 and 85 zenithal angles. It is shown that, under same deposition conditions, the concentration of internal nano-pores in SiO2 is higher than in TiO2 nanocolumns, while the situation is closer to this latter in TiO2/SiO2 multilayers. These features have been compared with the predictions of a Monte Carlo simulation of the film growth and explained by considering the influence of the chemical composition on the growth mechanism and, ultimately, on the structure of the films.


Marzo, 2020 | DOI: 10.1016/j.micromeso.2019.109968

Nanotecnología en Superficies y Plasma

Optofluidic liquid sensing on electromicrofluidic devices

Oliva-Ramirez, M; Wang, SL; Rico-Gavira, V; Lopez-Santos, C; Fan, SK; Gonzalez-Elipe, AR
Materials Research Express, 7 (2020) 036407

Electromicrofluidic (EMF) devices are used to handle and move tiny amounts of liquids by electrical actuation, including electrowetting-on-dielectric (EWOD) and dielectrophoresis (DEP). Monitoring the liquid characteristics in one of these devices requires suitable sensing transducers incorporated within the microfluidic structure. In the present work, we describe the incorporation of an optofluidic photonic transducer in an EMF device to monitor the refractive index of a liquid during its manipulation. The incorporated transducer consists of a responsive porous Bragg Microcavity (BM) deposited via physical vapor oblique angle deposition. Besides reporting the manufacturing procedure of the sensing-EMF device combining liquid handling and monitoring, the performance of the BM is verified by infiltrating several liquids dripped on its surface and comparing the responses with those of liquid droplets electrically moved from the delivery part of the chip to the BM location. This study proved that modified EMF devices can incorporate photonic structures to analyze very low liquid volumes (similar to 0.2 mu L) during its handling.


Marzo, 2020 | DOI: 10.1088/2053-1591/ab7fdf

Nanotecnología en Superficies y Plasma

Platinum nanoparticles stabilized by N-heterocyclic thiones. Synthesis and catalytic activity in mono- and di-hydroboration of alkynes

Moraes, LCC; Figueiredo, RCC; Espinos, JPP; Vattier, F; Franconetti, A; Jaime, C; Lacroix, B; Rojo, J; Lara, P; Conejero, S
Nanoscale, 12 (2020) 6821-6831

N-Heterocyclic Thiones (NHT) proved to be efficient ligands for the stabilization of small platinum nanoparticles (1.3-1.7 nm), synthesized by decomposition of [Pt(dba)(2)], under a H-2 atmosphere, in the presence of variable sub-stoichiometric amounts of the NHT. Full characterization by means of TEM, HR-TEM, NMR, ICP, TGA and XPS have been carried out, providing information about the nature of the metal nanoparticles and the interaction of the NHT ligands to the metal surface. Importantly, DFT calculations indicate that some NHT ligands interact with the metal through the C & xe001;C double bond of the imidazole fragment in addition to the sulfur atom, thus providing additional stabilization to the nanoparticles. According to XPS, TGA and ICP techniques, the surface coverage by the ligand increases by decreasing the size of the substituents on the nitrogen atom. The platinum nanoparticles have been used as catalyst in the hydroboration of alkynes. The most active system is that with a less covered surface area lacking an interaction of the ligand by means of the C & xe001;C double bond. This catalyst hydroborates alkynes with excellent selectivities towards the monoborylated anti-Markovnikov product (vinyl-boronate) when one equiv. of borane is used. Very interestingly, aliphatic alkynes undergo a second hydroborylation process leading to the corresponding 1,1- and 1,2-diboroylated species with good selectivities towards the former.


Marzo, 2020 | DOI: 10.1039/d0nr00251h

Nanotecnología en Superficies y Plasma

Robust label-free CuxCoyOz electrochemical sensors for hexose detection during fermentation process monitoring

Lopez-Fernandez, E; Gil-Rostra, J; Espinos, JP; Gonzalez, R; Yubero, F; de Lucas-Consuegra, A; Gonzalez-Elipe, AR
Sensors and Actuators B-Chemical, 304 (2020) 127360

Label free electrochemical sensors of glucose are used whenever long-term operation and stable response are required. For this purpose, various metals and oxides of the first transition series have been proposed as alternative to more expensive noble metal electrochemical sensors. In this work we propose a new formulation consisting of copper-cobalt mixed oxides which, in the form of porous and nanostructured thin films with well controlled Co/Cu ratio, are prepared at room temperature in one step by a modification of the magnetron sputtering oblique angle deposition procedure. Films with various compositions were electrochemically characterized by cyclic voltammetry to determine their amperometric response to glucose as a function of voltage and NaOH electrolyte concentration. This analysis showed that films with a Co/Cu atomic ratio equal 3.4 presented a maximum sensitivity (0.710 A M−1 cm−2), a small limit of detection (0.105 μM) and a resilient behaviour upon cycling operation and long storage periods that clearly overpassed the performance of copper and cobalt single oxides. The CuxCoyO electrocatalysts also presented a good selectivity towards glucose and fructose in the presence of common interference compounds found in biological fluids (e.g., ascorbic acid, acetaminophen and uric acid), sucrose and ethanol, this latter present in many agrofood liquids. The possibilities of this sensor electrocatalyst have been tested for the analysis of a wine synthetic fermentation process. The comparison of the electrochemical results with conventional analytical methods showed a lineal amperometric response with respect hexose contents in a must at different stages of its transformation into wine.


Febrero, 2020 | DOI: 10.1016/j.snb.2019.127360

Tribología y Protección de Superficies

Tribomechanical properties of hard Cr-doped DLC coatings deposited by low-frequency HiPIMS

Santiago, JA; Fernandez-Martinez, I; Sanchez-Lopez, JC; Rojas, TC; Wennberg, A; Bellido-Gonzalez, V; Molina-Aldareguia, JM; Monclus, MA; Gonzalez-Arrabal, R
Surface & Coatings Technology, 382 (2020) 124899

Cr-doped diamond-like carbon (Cr-DLC) films with Cr contents ranging from 3 up to 20 at. % were synthesised in a codeposition process with HiPIMS (Cr deposition) and DC-pulsed technology (C deposition). The application of HiPIMS at low frequencies was observed to significantly enhance the energy density during the Cr plasma discharge due to the interaction of Cr-C species. The higher energy bombardment at low HiPIMS frequencies allowed doping with Cr the DLC structure avoiding the graphitization of the carbon structure. EELS spectroscopy was used to evaluate sp(3) content and Raman was used for sp(2) structural characterization of the films. Enhanced mechanical properties (hardness up to 30 GPa) were observed with nanoindentation for Cr-doped DLC at low frequencies. High temperature nanoindentation tests were also performed from room temperature to 425 degrees C in order to evaluate the evolution of hardness and Young Modulus with temperature. The results showed that the mechanical properties at high temperature mainly depend on the initial sp(3)-sp(2) structure. Tribological tests were carried out in air from room temperature to 250 degrees C. Cr-doped DLC coatings deposited by low-frequency HiPIMS showed lower friction and wear compared to undoped DLC.


Enero, 2020 | DOI: 10.1016/j.surfcoat.2019.124899

Nanotecnología en Superficies y Plasma

Enhanced Stability of Perovskite Solar Cells Incorporating Dopant-Free Crystalline Spiro-OMeTAD Layers by Vacuum Sublimation

Barranco, A; Lopez-Santos, MC; Idigoras, J; Aparicio, FJ; Obrero-Perez, J; Lopez-Flores, V; Contreras-Bernal, L; Rico, V; Ferrer, J; Espinos, JP; Borras, A; Anta, JA; Sanchez-Valencia, JR
Advanced Energy Materials, (2020) 1901524

The main handicap still hindering the eventual exploitation of organometal halide perovskite-based solar cells is their poor stability under prolonged illumination, ambient conditions, and increased temperatures. This article shows for the first time the vacuum processing of the most widely used solid-state hole conductor (SSHC), i.e., the Spiro-OMeTAD [2,2 ',7,7 '-tetrakis (N,N-di-p-methoxyphenyl-amine) 9,9 '-spirobifluorene], and how its dopant-free crystalline formation unprecedently improves perovskite solar cell (PSC) stability under continuous illumination by about two orders of magnitude with respect to the solution-processed reference and after annealing in air up to 200 degrees C. It is demonstrated that the control over the temperature of the samples during the vacuum deposition enhances the crystallinity of the SSHC, obtaining a preferential orientation along the pi-pi stacking direction. These results may represent a milestone toward the full vacuum processing of hybrid organic halide PSCs as well as light-emitting diodes, with promising impacts on the development of durable devices. The microstructure, purity, and crystallinity of the vacuum sublimated Spiro-OMeTAD layers are fully elucidated by applying an unparalleled set of complementary characterization techniques, including scanning electron microscopy, X-ray diffraction, grazing-incidence small-angle X-ray scattering and grazing-incidence wide-angle X-ray scattering, X-ray photoelectron spectroscopy, and Rutherford backscattering spectroscopy.


Enero, 2020 | DOI: 10.1002/aenm.201901524

Materiales Nanoestructurados y Microestructura

Low gas consumption fabrication of He-3 solid targets for nuclear reactions

Fernandez, A; Hufschmidt, D; Colaux, JL; Valiente-Dobon, JJ; Godinho, V; de Haro, MCJ; Feria, D; Gadea, A; Lucas, S
Materials & Design, 186 (2020) 108337

Nanoporous solids that stabilize trapped gas nanobubbles open new possibilities to fabricate solid targets for nuclear reactions. A methodology is described based on the magnetron sputtering (MS) technique operated under quasistatic flux conditions to produce such nanocomposites films with He-3 contents of up to 16 at.% in an amorphous-silicon matrix. In addition to the characteristic low pressure (3-6 Pa) needed for the gas discharge, the method ensures almost complete reduction of the process gas flow during film fabrication. The method could produce similar materials to those obtained under classical dynamic flux conditions for MS. The drastic reduction (>99.5%) of the gas consumption is fundamental for the fabrication of targets with scarce and expensive gases. Si:He-3 and W:He-3 targets are presented together with their microstructural (scanning and transmission electron microscopy, SEM and TEM respectively) and compositional (Ion Beam Analysis, IBA) characterization. The He-3 content achieved was over 1 x 10(18) at/cm(2) for film thicknesses between 1.5 and 3 mu m for both Si and W matrices. First experiments to probe the stability of the targets for nuclear reaction studies in inverse kinematics configurations are presented. 


Enero, 2020 | DOI: 10.1016/j.matdes.2019.108337



2019


Nanotecnología en Superficies y Plasma

Hydrophobic and Icephobic Behaviour of Polyurethane-Based Nanocomposite Coatings

Przybyszewski, B; Boczkowska, A; Kozera, R; Mora, J; Garcia, P; Aguero, A; Borras, A
Coatings, 9 (2019) 811

In this paper, hydrophobic nanocomposite coatings based on polyurethane (PUR) modified by nano-silica and silane-based compounds were manufactured by spraying. The main challenge was to assess and improve the hydrophobic as well as anti-icing properties of initially hydrophilic polymer coatings. The prepared nanocomposite coatings were characterized by means of scanning electron microscopy (SEM), optical profilometry and X-ray photoelectron spectroscopy (XPS). The results obtained showed that in order to achieve hydrophobicity, appropriate amounts of nano-silica must be incorporated in the coating, and complete coverage by nano-silica particles is necessary for achieving hydrophobicity. Coating adhesion and the durability of the hydrophobic behaviour were also studied by scratch test and frosting/defrosting cycles, respectively. The results show that use of both nano-silica and silane-based compounds improve the hydrophobic and anti-icing properties of the coating as compared to a non-modified PUR topcoat. A synergistic effect of both additives was observed. It was also found that the anti-icing behaviour does not necessarily correlate with surface roughness and the materials' wetting properties.


Diciembre, 2019 | DOI: 10.3390/coatings9120811

Nanotecnología en Superficies y Plasma

Graphene Formation Mechanism by the Electrochemical Promotion of a Ni Catalyst

Espinos, JP; Rico, VJ; Gonzalez-Cobos, J; Sanchez-Valencia, JR; Perez-Dieste, V; Escudero, C; de Lucas-Consuegra, A; Gonzalez-Elipe, AR
ACS Catalysis, 9 (2019) 11447-11454

In this work, we show that multilayer graphene forms by methanol decomposition at 280 degrees C on an electrochemically promoted nickel catalyst film supported on a K-beta Al2O3 solid electrolyte. In operando near ambient pressure photoemission spectroscopy and electrochemical measurements have shown that polarizing negatively the Ni electrode induces the electrochemical reduction and migration of potassium to the nickel surface. This elemental potassium promotes the catalytic decomposition of methanol into graphene and also stabilizes the graphene formed via diffusion and direct K-C interaction. Experiments reveal that adsorbed methoxy radicals are intermediate species in this process and that, once formed, multilayer graphene remains stable after electrochemical oxidation and back migration of potassium to the solid electrolyte upon positive polarization. The reversible diffusion of ca. 100 equivalent monolayers of potassium through the carbon layers and the unprecedented low-temperature formation of graphene and other carbon forms are mechanistic pathways of high potential impact for applications where mild synthesis and operation conditions are required.


Diciembre, 2019 | DOI: 10.1021/acscatal.9b03820

Tribología y Protección de Superficies

Silver effect on the tribological and antibacterial properties of a-C:Ag coatings

Dominguez-Meister, S; Rojas, TC; Frias, JE; Sanchez-Lopez, JC
Tribology International, 140 (2019) UNSP 105837

a-C:Ag coatings (1.2-23.4 at.% of Ag) were deposited using magnetron sputtering. Ag nanoparticles appear embedded in the carbon matrix or segregated to the column boundaries or surface. The silver doping has not promoted significant changes of the sp(2)/sp(3) ratio although a decrease of the hardness is observed (from 17 to 7 GPa). The tribological behavior did not show a clear dependence on the silver concentration in unlubricated or lubricated conditions (fetal bovinum serum) against alumina or UHMWPE balls. Ag nanoparticle dispersion enhanced the bactericide behavior as determined by the released Ag+ ion in the fluid media. There is no clear effect of friction rubbing on the released silver indicating that diffusion and top segregation are prevalent mechanisms for its dissolution.


Diciembre, 2019 | DOI: 10.1016/j.triboint.2019.06.030

Nanotecnología en Superficies y Plasma

3D Organic Nanofabrics: Plasma-Assisted Synthesis and Antifreezing Behavior of Superhydrophobic and Lubricant-Infused Slippery Surfaces

Alcaire, M; Lopez-Santos, C; Aparicio, FJ; Sanchez-Valencia, JR; Obrero, JM; Saghi, Z; Rico, VJ; de la Fuente, G; Gonzalez-Elipe, AR; Barranco, A; Borras, A
Langmuir, 35 (2019) 16876-16885

Herein, we present the development of supported organic nanofabrics formed by a conformal polymer-like interconnection of small-molecule organic nanowires and nanotrees. These organic nanostructures are fabricated by a combination of vacuum and plasma-assisted deposition techniques to generate step by step, single-crystalline organic nanowires forming one-dimensional building blocks, organic nanotrees applied as three-dimensional templates, and the polymer-like shell that produces the final fabric. The complete procedure is carried out at low temperatures and is compatible with an ample variety of substrates (polymers, metal, ceramics; either planar or in the form of meshes) yielding flexible and low solid-fraction three-dimensional nanostructures. The systematic investigation of this progressively complex organic nanomaterial delivers key clues relating their wetting, nonwetting, and anti-icing properties with their specific morphology and outer surface composition. Water contact angles higher than 150° are attainable as a function of the nanofabric shell thickness with outstanding freezing-delay times (FDT) longer than 2 h at −5 °C. The role of the extremely low roughness of the shell surface is settled as a critical feature for such an achievement. In addition, the characteristic interconnected microstructure of the nanofabrics is demonstrated as ideal for the fabrication of slippery liquid-infused porous surfaces (SLIPS). We present the straightforward deposition of the nanofabric on laser patterns and the knowledge of how this approach provides SLIPS with FDTs longer than 5 h at −5 °C and 1 h at −15 °C.


Diciembre, 2019 | DOI: 10.1021/acs.langmuir.9b03116

Materiales Nanoestructurados y Microestructura

Morphological effects on the photocatalytic properties of SnO2 nanostructures

Kar, A; Olszowka, J; Sain, S; Sloman, SRI; Montes, O; Fernandez, A; Pradhan, SK; Wheatley, AEH
Journal of Alloys and Compounds, 810 (2019) UNSP 151718

The photocatalytic properties of SnO2 nanocrystals are tuned by varying their morphology and microstructure. SnO2 nanoparticles and nanowedges have been synthesized using hydrothermal methods, while microwave irradiation techniques have given nanospheres. Detailed structural and chemical characterization of these different morphologies has been accomplished. The influence of SnO2 morphology on photocatalytic activity has been examined by monitoring the degradation of aqueous methylene blue dye. Results demonstrate that changing the morphology of the SnO2 modulates both surface area and levels of surface defects and that these alterations are reflected in the photocatalytic properties of the materials. The degradation of methylene blue dye (98%) in the presence of SnO2 nanoparticles under simulated solar irradiation is superior to previously reported photocatalyst performance and is comparable to that of standard TiO2 (Degussa P-25). The SnO2 nanoparticles perform better than both the nanowedges and nanospheres and this is attributed to the number of surface defects available to the high surface area material. They also reveal outstanding recyclability and stability. 


Noviembre, 2019 | DOI: 10.1016/j.jallcom.2019.151718

Nanotecnología en Superficies y Plasma

Kinetic energy-induced growth regimes of nanocolumnar Ti thin films deposited by evaporation and magnetron sputtering

Alvarez, R.; Garcia-Valenzuela, A.; Rico, V; Garcia-Martin, J. M.; Cotrino, J.; Gonzalez-Elipe, A. R.; Palmero, A.
Nanotechnology, 30 (2019) 475603

We experimentally analyze different growth regimes of Ti thin films associated to the existence of kinetic energy-induced relaxation mechanisms in the material's network when operating at oblique geometries. For this purpose, we have deposited different films by evaporation and magnetron sputtering under similar geometrical arrangements and at low temperatures. With the help of a well-established growth model we have found three different growth regimes: (i) low energy deposition, exemplified by the evaporation technique, carried out by species with typical energies in the thermal range, where the morphology and density of the film can be explained by solely considering surface shadowing processes, (ii) magnetron sputtering under weak plasma conditions, where the film growth is mediated by surface shadowing mechanisms and kinetic-energy-induced relaxation processes, and (iii) magnetron sputtering under intense plasma conditions, where the film growth is highly influenced by the plasma, and whose morphology is defined by nanocolumns with similar tilt than evaporated films, but with much higher density. The existence of these three regimes explains the variety of morphologies of nanocolumnar Ti thin films grown at oblique angles under similar conditions in the literature.


Noviembre, 2019 | DOI: 10.1088/1361-6528/ab3cb2

Nanotecnología en Superficies y Plasma

Ultrastable CoxSiyOz Nanowires by Glancing Angle Deposition with Magnetron Sputtering as Novel Electrocatalyst for Water Oxidation

Cano, M; Garcia-Garcia, FJ; Rodriguez-Padron, D; Gonzalez-Elipe, AR; Giner-Casares, JJ; Luque, R
Chemcatchem

Cobalt is one of the most promising non-noble metal as electrocatalyst for water oxidation. Herein, a highly stable silicon-cobalt mixed oxide thin film with a porous columnar nanostructure is proposed as electrocatalyst for oxygen evolution reaction (OER). CoOx and CoxSiyOz layers with similar thickness were fabricated at room temperature by magnetron sputtering in a glancing angle configuration (MS-GLAD) on tin-doped indium oxide (ITO) substrates. After characterization, a comparative study of the electrocatalytic performance for OER of both layers was carried out. The excellent long-term stability as electrocatalyst for OER of the porous CoxSiyOz thin film demonstrates that the presence of silicon on the mixed oxide network increases the mechanical stability of the Si/Co layer, whilst maintaining a considerable electrocatalytic response.


Noviembre, 2019 | DOI: 10.1002/cctc.201901730

Nanotecnología en Superficies y Plasma

Highly selective few-ppm NO gas-sensing based on necklace-like nanofibers of ZnO/CdO n-n type I heterojunction

Naderi, H; Hajati, S; Ghaedi, M; Espinos, JP
Sensors and Actuators B-Chemical, 297 (2019) 126774

Electrospinning method followed by calcination is applied to synthesize ZnO/CdO nanofibers. Characterization is performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and reflection electron energy loss spectroscopy (REELS), which resulted in detailed analysis of the sensing material. For instance, it was found that the ZnO/CdO is n-n type I heterojunction which possesses straddling energy band gap, which could affect the mechanism of gas sensing. An electroless gold-plated interdigitated electrode with spacing 200 mu m is fabricated on alumina substrate to host the designed nanofibers being used as gas sensor. Gas-sensing activity of the heterojunction is investigated against NO, NO2, H2S, CH4, SO2 and CO in addition to VOCs such as ethanol, acetone, ammonia, methanol, and chloroform with high selectivity and response to NO gas by monitoring resistance changes. Detailed discussion on the mechanism of sensing is presented. The ZnO/CdO nanofibers are found to be highly sensitive to very low concentration range of NO gas (1.2-33 ppm) at optimal operating temperature of 215 degrees C. The influence of humidity (20-96%) on the sensor response was found to be ignorable. Additionally, good repeatability and long-term stability (45 days, every 5 days, SD = 0.7) was obtained for this sensor. Typically, short response times of 47 and 35 s are obtained versus 3 and 33 ppm of NO, respectively, making our sensor promisingly applicable for monitoring this toxic gas in polluting industries, metropolises and maybe in exhaled breath.


Octubre, 2019 | DOI: 10.1016/j.snb.2019.126774

Nanotecnología en Superficies y Plasma

Sodium ion storage performance of magnetron sputtered WO3 thin films

Garcia-Garcia, FJ; Mosa, J; Gonzalez-Elipe, AR; Aparicio, M
Electrochimica Acta, 321 (2019) 134669

WO3 thin film electrodes were successfully prepared by magnetron sputtering (MS) deposition under an oblique angle configuration (OAD). Intercalation of Na ions in the tungsten oxide layers has been studied using electrochemical techniques. Sample characterization before and after sodium intercalation has been carried out by Raman, XPS and XRD measurements. ToF-SIMS analysis has been also performed in order to analyze the element depth profiles along the electrode thickness. Electron microscopy evaluation of the cross section confirms the porous structure of the coatings. Batteries integrating these WO3 electrodes have a discharge capacity of 120 mA h g(-1) at the initial cycles and show an adequate capacity retention upon 300 cycles. The WO3-OAD thin-films are proposed as promising electrodes for Na-ion batteries.


Octubre, 2019 | DOI: 10.1016/j.electacta.2019.134669

Nanotecnología en Superficies y Plasma

Influence of Titanium Oxide Pillar Array Nanometric Structures and Ultraviolet Irradiation on the Properties of the Surface of Dental Implants-A Pilot Study

Leon-Ramos, JR; Diosdado-Cano, JM; Lopez-Santos, C; Barranco, A; Torres-Lagares, D; Serrera-Figallo, MA
Nanomaterials, 9 (2019) 1458

Aim: Titanium implants are commonly used as replacement therapy for lost teeth and much current research is focusing on the improvement of the chemical and physical properties of their surfaces in order to improve the osseointegration process. TiO2, when it is deposited in the form of pillar array nanometric structures, has photocatalytic properties and wet surface control, which, together with UV irradiation, provide it with superhydrophilic surfaces, which may be of interest for improving cell adhesion on the peri-implant surface. In this article, we address the influence of this type of surface treatment on type IV and type V titanium discs on their surface energy and cell growth on them. Materials and methods: Samples from titanium rods used for making dental implants were used. There were two types of samples: grade IV and grade V. In turn, within each grade, two types of samples were differentiated: untreated and treated with sand blasting and subjected to double acid etching. Synthesis of the film consisting of titanium oxide pillar array structures was carried out using plasma-enhanced chemical vapor deposition equipment. The plasma was generated in a quartz vessel by an external SLAN-1 microwave source with a frequency of 2.45 GHz. Five specimens from each group were used (40 discs in total). On the surfaces to be studied, the following determinations were carried out: (a) X-ray photoelectron spectroscopy, (b) scanning electron microscopy, (c) energy dispersive X-ray spectroscopy, (d) profilometry, (e) contact angle measurement or surface wettability, (f) progression of contact angle on applying ultraviolet irradiation, and (g) a biocompatibility test and cytotoxicity with cell cultures. Results: The application of ultraviolet light decreased the hydrophobicity of all the surfaces studied, although it did so to a greater extent on the surfaces with the studied modification applied, this being more evident in samples manufactured in grade V titanium. In samples made in grade IV titanium, this difference was less evident, and even in the sample manufactured with grade IV and SLA treatment, the application of the nanometric modification of the surface made the surface optically less active. Regarding cell growth, all the surfaces studied, grouped in relation to the presence or not of the nanometric treatment, showed similar growth. Conclusions. Treatment of titanium oxide surfaces with ultraviolet irradiation made them change temporarily into superhydrophilic ones, which confirms that their biocompatibility could be improved in this way, or at least be maintained.


Octubre, 2019 | DOI: 10.3390/nano9101458

Nanotecnología en Superficies y Plasma

Antibacterial Nanostructured Ti Coatings by Magnetron Sputtering: From Laboratory Scales to Industrial Reactors

Alvarez, R; Munoz-Pina, S; Gonzalez, MU; Izquierdo-Barba, I; Fernandez-Martinez, I; Rico, V; Arcos, D; Garcia-Valenzuela, A; Palmero, A; Vallet-Regi, M; Gonzalez-Elipe, AR; Garcia-Martin, JM
Nanomaterials, 9 (2019) art. 1217

Based on an already tested laboratory procedure, a new magnetron sputtering methodology to simultaneously coat two-sides of large area implants (up to similar to 15 cm(2)) with Ti nanocolumns in industrial reactors has been developed. By analyzing the required growth conditions in a laboratory setup, a new geometry and methodology have been proposed and tested in a semi-industrial scale reactor. A bone plate (DePuy Synthes) and a pseudo-rectangular bone plate extracted from a patient were coated following the new methodology, obtaining that their osteoblast proliferation efficiency and antibacterial functionality were equivalent to the coatings grown in the laboratory reactor on small areas. In particular, two kinds of experiments were performed: Analysis of bacterial adhesion and biofilm formation, and osteoblasts-bacteria competitive in vitro growth scenarios. In all these cases, the coatings show an opposite behavior toward osteoblast and bacterial proliferation, demonstrating that the proposed methodology represents a valid approach for industrial production and practical application of nanostructured titanium coatings.


Septiembre, 2019 | DOI: 10.3390/nano9091217

Nanotecnología en Superficies y Plasma

SiOx by magnetron sputtered revisited: Tailoring the photonic properties of multilayers

Garcia-Valenzuela, A; Alvarez, R; Espinos, JP; Rico, V; Gil-Rostra, J; Palmero, A; Gonzalez-Elipe, AR
Applied Surface Science, 488 (2019) 791-800

Traditionally porous silicon based photonic structures have been prepared by electrochemically etching of silicon. In this work, porous multilayers of nanocolumnar SiOx and SiO2 thin films acting as near infrared (NIR) 1D-photonic nanostructures are prepared by magnetron sputtering deposition at oblique angles (MS-OA). Simultaneous control of porosity and stoichiometry of the stacked films is achieved by adjusting the deposition angle and oxygen partial pressure according to a parametric formula. This new methodologoy is proved for the synthesis of SiOx thin films with x close to 0.4, 0.8, 1.2, 1.6 and nanostructures varying from compact (at 0 degrees deposition angle) to highly porous and nanocolumnar (at 70 degrees and 85 degrees deposition angles). The strict control of composition, structure and nanostructure provided by this technique permits a fine tuning of the absorption edge and refraction index at 1500 nm of the porous films and their manufacturing in the form of SiOx-SiO2 porous multilayers acting as near infrared (NIR) 1D-photonic structures with well-defined optofluidic responses. Liquid tunable NIR Bragg mirrors and Bragg microcavities for liquid sensing applications are presented as proof of concept of the possibilities of this MS-OA manufacturing method as an alternative to the conventional electrochemical fabrication of silicon based photonic structures.


Septiembre, 2019 | DOI: 10.1016/j.apsusc.2019.05.273

Materiales para Bioingeniería y Regeneración Tisular

Higher hydration performance and bioactive response of the new endodontic bioactive cement MTA HP repair compared with ProRoot MTA white and NeoMTA plus

Jimenez-Sanchez, Maria Del Carmen; Segura-Egea, Juan Jose; Diaz-Cuenca, Aranzazu
Journal of biomedical materials research. Part B, Applied biomaterials, 107 (2019) 2109-2120

The aim of this study was to characterize the hydration performance and the bioactive response of the new bioactive endodontic cement MTA HP repair (HP), comparing its physicochemical parameters with those of ProRoot MTA White (Pro) and NeoMTA Plus (Neo). Un-hydrated precursor materials were characterized by X-ray fluorescence, laser diffraction, N2 physisorption and field emission gun scanning electron microscopy (FEG-SEM). Setting time was assessed according to ASTM specification C 266. Hydrated materials were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR) and (FEG-SEM). Bioactivity evaluation in vitro was carried out, by soaking processed cement disk in simulated body fluid (SBF) during 168 h. The cements surface was studied by FT-IR, FEG-SEM, and energy dispersive X-ray. Release to the SBF media of ionic degradation products was monitored using inductively coupled plasma atomic emission spectroscopy. HP showed shorter initial setting time compared to Pro and Neo and produce a quick and effective bioactive response in vitro in terms of phosphate phase surface coating formation. This higher bioactive response for HP is correlated with increasing calcium aluminate content, increasing surface area of un-hydrated powder precursor and the increasing release capacity of Si ionic products of the final hydrated product. The higher bioactive response of MTA HP repair highlights this material, as very interesting to further investigate its performance to improve the outcome of vital pulp therapy procedures. 


Agosto, 2019 | DOI: 10.1002/jbm.b.34304

Materiales para Bioingeniería y Regeneración Tisular

MTA HP Repair stimulates in vitro an homogeneous calcium phosphate phase coating deposition

Jiménez-Sánchez, M.D.C.; Segura-Egea, J.J.; Díaz-Cuenca, A.
Journal of Clinical and Experimental Dentistry, 11 (2019) e322-e326

Background: To study the mineralization capacity in vitro of the bioceramic endodontic material MTA HP Repair. Material and Methods: Bioactivity evaluation in vitro was carried out, by soaking processed cement disk in simulated body fluid (SBF) during 168 h. The cement surface was studied by Fourier transform infrared spectroscopy (FTIR), field emission gun scanning electron microscopy (FEG-SEM) and energy dispersive X-ray analysis (EDX). Release to the SBF media of ionic degradation products was monitored using inductively coupled plasma atomic emission spectroscopy (ICP-AES). Results: FT-IR showed increasing formation of phosphate phase bands at 1097, 960, 607 and 570 cm -1 with prolonged SBF soaking. FEG-SEM analysis reveals that HP produces a effectively surface covering consisting in homogeneous spherical phosphate phase aggregates with an average diameter of 0.5 -1 .0 μm. EDX analysis comparing un-treated (hydrated), 24 h and 72 h SBF treated surfaces of MTA HP Repair revealed phosphate deposition after 24 h, with high phosphorous/silicon element ratio signal measured after 24 h, indicating a very high phosphate phase deposition for this material. Conclusions: The study shows that MTA HP Repair produces a quick and effective bioactive response in vitro in terms of crystalline calcium phosphate surface coating formation. The high bioactive response of MTA HP Repair makes it an interesting candidate for endodontic use as repair cement. 


Agosto, 2019 | DOI: 10.4317/jced.55661

Materiales para Bioingeniería y Regeneración Tisular

Physicochemical parameters - hydration performance relationship of the new endodontic cement MTA Repair HP

Jiménez-Sánchez, M.D.C.; Segura-Egea, J.J.; Díaz-Cuenca, A.
Journal of Clinical and Experimental Dentistry, 11 (2019) e739-e744

Background: To characterize the chemical composition and textural parameters of the MTA Repair HP precursor powder and their influence to hydration performance. Material and Methods: Un-hydrated precursor material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), laser diffraction (LD), N2 physisorption and field emission gun scanning electron microscopy (FEG-SEM). Setting time was assessed according to ASTM specification C 266. Hydrated material was analysed by XRD, FT-IR, energy dispersive X-ray (EDX) analysis and FEG-SEM. Results: Ca3SiO5 and Ca2SiO4, in addition to CaWO4 as radiopacifier are the main compositional phases. Other measured parameters indicate high specific surface area of 4.8 m2 g-1, high aluminium content of 1.7 wt.% and low initial and final setting times of 12 and 199 min, respectively. Singular microstructural features consisting of high aspect ratio nanoparticles are main constituents of un-hydrated precursor. Besides, FEM-SEM observation shows notably growth of hexagonal shaped plate-like morphologies homogeneously distributed along the sample during hydration process. Conclusions: The short setting time measured for HP Repair, is correlated with high surface area of precursor powder, high Al content and the absence of compositional sulphate phases. 


Agosto, 2019 | DOI: 10.4317/jced.56013

Nanotecnología en Superficies y Plasma

Plasma Enabled Conformal and Damage Free Encapsulation of Fragile Molecular Matter: from Surface-Supported to On-Device Nanostructures

Alcaire, M; Aparicio, FJ; Obrero, J; Lopez-Santos, C; Garcia-Garcia, FJ; Sanchez-Valencia, JR; Frutos, F; Ostrikov, K; Borras, A; Barranco, A
Advanced Functional Materials, (2019) art. 1903535

Damage-free encapsulation of molecular structures with functional nanolayers is crucial to protect nanodevices from environmental exposure. With nanoscale electronic, optoelectronic, photonic, sensing, and other nanodevices based on atomically thin and fragile organic matter shrinking in size, it becomes increasingly challenging to develop nanoencapsulation that is simultaneously conformal at atomic scale and does not damage fragile molecular networks, while delivering added device functionality. This work presents an effective, plasma-enabled, potentially universal approach to produce highly conformal multifunctional organic films to encapsulate atomically thin graphene layers and metalorganic nanowires, without affecting their molecular structure and atomic bonding. Deposition of adamantane precursor and gentle remote plasma chemical vapor deposition are synergized to assemble molecular fragments and cage-like building blocks and completely encapsulate not only the molecular structures, but also the growth substrates and device elements upon nanowire integration. The films are insulating, transparent, and conformal at sub-nanometer scale even on near-tip high-curvature areas of high-aspect-ratio nanowires. The encapsulated structures are multifunctional and provide effective electric isolation, chemical and environmental protection, and transparency in the near-UV-visible-near-infrared range. This single-step, solvent-free remote-plasma approach preserves and guides molecular building blocks thus opening new avenues for precise, atomically conformal nanofabrication of fragile nanoscale matter with multiple functionalities.


Julio, 2019 | DOI: 10.1002/adfm.201903535

Nanotecnología en Superficies y Plasma

Large gap atmospheric pressure barrier discharges using ferroelectric materials

Navascues, P.; Gonzalez-Elipe, A. R.; Cotrino, J.; Gomez-Ramirez, A.
Plasma Sources Sciences & Tecnology, 28 (2019) 075002

This work reports a phenomenological comparative study of atmospheric pressure barrier plasmas using ferroelectric (ferroelectric barrier discharge (FBD)) and dielectric (dielectric barrier discharge (DBD)) plates to moderate the discharge. For FBD operation and large inter-electrode distances, experiments with helium carried out in a parallel plate reactor as a function of applied voltage have shown an enhancement of one order of magnitude in the charge transferred through the circuit. In a similar way to DBDs, FBDs rendered a laterally localized arrangement of discrete columnar discharges with a pattern distribution and an overall current intensity that depended on operation conditions. However, unlike the regular columnar pattern found for DBD operation, discharge columns in the FBD mode appear randomly and inhomogeneously distributed on the ferroelectric surface. This geometrical behavior of FBD plasma columns, as well as the singular variation of current with applied voltage and the particular shape characteristics of the current discharge curves have been accounted for by the high capacity of ferroelectric surfaces to randomly accumulate charge and to promote the emission of secondary electrons in the presence of a plasma.


Julio, 2019 | DOI: 10.1088/1361-6595/ab28ce

Nanotecnología en Superficies y Plasma

On‐Surface Synthesis and Characterization of Acene‐Based Nanoribbons Incorporating Four‐Membered Rings

Sanchez-Sanchez, C; Dienel, T; Nicolai, A; Kharche, N; Liang, LB; Daniels, C; Meunier, V; Liu, JZ; Feng, XL; Mullen, K; Sanchez-Valencia, JR; Groning, O; Ruffieux, P; Fasel, R
Chemistry-A European Journal

A bottom up method for the synthesis of unique tetracene-based nanoribbons, which incorporate cyclobutadiene moieties as linkers between the acene segments, is reported. These structures were achieved through the formal [2+2] cycloaddition reaction of ortho-functionalized tetracene precursor monomers. The formation mechanism and the electronic and magnetic properties of these nanoribbons were comprehensively studied by means of a multitechnique approach. Ultra-high vacuum scanning tunneling microscopy showed the occurrence of metal-coordinated nanostructures at room temperature and their evolution into nanoribbons through formal [2+2] cycloaddition at 475 K. Frequency-shift non-contact atomic force microscopy images clearly proved the presence of bridging cyclobutadiene moieties upon covalent coupling of activated tetracene molecules. Insight into the electronic and vibrational properties of the so-formed ribbons was obtained by scanning tunneling microscopy, Raman spectroscopy, and theoretical calculations. Magnetic properties were addressed from a computational point of view, allowing us to propose promising candidates to magnetic acene-based ribbons incorporating four-membered rings. The reported findings will increase the understanding and availability of new graphene-based nanoribbons with high potential in future spintronics.


Julio, 2019 | DOI: 10.1002/chem.201901410

Nanotecnología en Superficies y Plasma

2D compositional self-patterning in magnetron sputtered thin films

Garcia-Valenzuela, A; Alvarez, R; Rico, V; Espinos, JP; Lopez-Santos, MC; Solis, J; Siegel, J; del Campo, A; Palmero, A; Gonzalez-Elipe, AR
Applied Surface Science, 480 (2019) 115-121

Unlike topography patterning, widely used for numerous applications and produced by means of different technologies, there are no simple procedures to achieve surface compositional patterning at nanometric scales. In this work we have developed a simple method for 2D patterning the composition of thin films. The method relies on the magnetron sputtering deposition at oblique angles onto patterned substrates made by laser induced periodic surface structures (LIPSS). The method feasibility has been demonstrated by depositing SiOx thin films onto LIPSS structures generated in Cr layers. A heterogeneous and aligned distribution of O/Si ratios (and different Sin+ chemical states) along the LIPSS structure in length scales of some hundreds nm's has been proven by angle resolved X-ray photoelectron spectroscopy and a patterned arrangement of composition monitored by atomic force microscopy-Raman analysis. The obtained results are explained by the predictions of a Monte Carlo simulation of this deposition process and open the way for the tailored one-step fabrication of surface devices with patterned compositions.


Junio, 2019 | DOI: 10.1016/j.apsusc.2019.02.206

Materiales Nanoestructurados y Microestructura

Exchange bias and two steps magnetization reversal in porous Co/CoO layer

Ovejero, JG; Godinho, V; Lacroix, B; Garcia, MA; Hernando, A; Fernandez, A
Materials & Design, 171 (2019) 107691

In this paper Co/CoO thick layers (hundreds of nanometers) of different porosity and oxidation degree were prepared in a magnetron sputtering deposition processby tailoring the DC sputtering power, as well as the process gas and target composition. The control of the synthesis parameters allowed the nanostructuration of the films with a singular distribution of closed pores and a controlled amount of CoO. We observed an exchange bias field of 2.8 KOe for porous Co/CoO composites, similar to Co/CoO bilayers but for coatings thicker than 300 nm. Besides, it was observed that the coating presents bistable magnetic features when cooled under zero field conditions as a result of the unusual exchange coupling.


Junio, 2019 | DOI: 10.1016/j.matdes.2019.107691

Nanotecnología en Superficies y Plasma

Multifunctional antimicrobial chlorhexidine polymers by remote plasma assisted vacuum deposition

Mora-Boza, A; Aparicio, FJ; Alcaire, M; Lopez-Santos, C; Espinos, JP; Torres-Lagares, D; Borras, A; Barranco, A
Frontiers of chemical science and engineering, 13 (2019) 330-339

Novel antibacterial materials for implants and medical instruments are essential to develop practical strategies to stop the spread of healthcare associated infections. This study presents the synthesis of multifunctional antibacterial nanocoatings on polydimethylsiloxane (PDMS) by remote plasma assisted deposition of sublimated chlorhexidine powders at low pressure and room temperature. The obtained materials present effective antibacterial activity against Escherichia coli K12, either by contact killing and antibacterial adhesion or by biocide agents release depending on the synthetic parameters. In addition, these multifunctional coatings allow the endure hydrophilization of the hydrophobic PDMS surface, thereby improving their biocompatibility. Importantly, cell-viability tests conducted on these materials also prove their non-cytotoxicity, opening a way for the integration of this type of functional plasma films in biomedical devices.


Junio, 2019 | DOI: 10.1007/s11705-019-1803-6

Nanotecnología en Superficies y Plasma

Liquid switchable radial polarization converters made of sculptured thin films

Oliva-Ramirez, M; Rico, VJ; Gil-Rostra, J; Arteaga, O; Bertran, E; Serna, R; Gonzalez-Elip, AR; Yubero, F
Applied Surface Science, 475 (2019) 230-236

A radial polarization converter is a super-structured optical retarder that converts a conventional linearly polarized light beam into a structured beam with radial or azimuthal polarization. We present a new type of these sophisticated optical elements, which is made of porous nanostructured sculptured single thin films or multilayers prepared by physical vapor deposition at an oblique angle. They are bestowed with an axisymmetric retardation activity (with the fast axis in a radial configuration). In particular, a Bragg microcavity multilayer that exhibits a tunable transmission peak in the visible range with a retardance of up to 0.35 rad has been fabricated using this methodology. Owing to the highly porous structure of this type of thin films and multilayers, their retardance could be switched off by liquid infiltration. These results prove the possibility of developing wavelength dependent (through multilayer optical design) and switchable (through vapor condensation or liquid infiltration within the pore structure) radial polarization converters by means of oblique angle physical vapor deposition.


Mayo, 2019 | DOI: 10.1016/j.apsusc.2018.12.200

Materiales Nanoestructurados y Microestructura

Surface nickel particles generated by exsolution from a perovskite structure

Aguero, FN; Beltran, AM; Fernandez, MA; Cadus, LE
Journal of Solid State Chemistry, 273 (2019) 75-80

LaAl1-xNixO3 (with x = 0.05 and 0.2) perovskite oxides were successfully synthesized and its behavior under reduction atmosphere was studied. HRTEM and STEM studies, coupled to HAADF and EDX detection, allowed to evidence the Ni exsolution process to the surface of the solid and to build nano-catalytic centers. The size of these centers is independent of the reduction conditions in the range studied. The high specific surface of the raw material, its porosity and the structure defects could be responsible of the low temperature at which the exsolution process starts. The content of Ni dopants allows the control of Ni centers size on the surface and the synthesis method provides Ni-nanoparticles strongly anchored to the resultant support.


Mayo, 2019 | DOI: 10.1016/j.jssc.2019.02.036

Nanotecnología en Superficies y Plasma

Hydrophobicity, Freezing Delay, and Morphology of Laser-Treated Aluminum Surfaces

Rico, VJ; Lopez-Santos, C; Villagra, M; Espinos, JP; de la Fuente, GF; Angurel, LA; Borras, A; Gonzalez-Elipe, AR
Langmuir, 35 (2019) 6483-6491

Until recently, superhydrophobicity was considered as a hint to predict surface icephobicity, an association of concepts that is by no means universal and that has been proven to depend on different experimental factors and material properties, including the actual morphology and chemical state of surfaces. This work presents a systematic study of the wetting and freezing properties of aluminum Al6061, a common material widely used in aviation, after being subjected to nanosecond pulsed IR laser treatments to modify its surface roughness and morphology. All treated samples, independent of their surface finishing state, presented initially an unstable hydrophilic wetting behavior that naturally evolved with time to reach hydrophobicity or even superhydrophobicity. To stabilize the surface state and to bestow the samples with a permanent and stable hydrophobic character, laser-treated surfaces were covered with a thin layer of CFx prepared by plasma-enhanced chemical vapor deposition. A systematic comparison between freezing delay (FD) and wetting properties of water droplets onto these plasma-/polymer-modified laser-treated surfaces that, under conditions where a heterogeneous nucleation mechanism prevails, surface morphology rather than the actual value of the surface roughness parameter the key feature for long FD times. In particular, it is found that surface morphologies rendering a Cassie-Baxter wetting regime longer FDs than those characterized by a Wenzel-like wetting state. It is that laser treatment, with or without additional coverage with thin CFx coatings, affects wetting and ice formation behaviors and might be an efficient procedure to mitigate icing problems on metal surfaces.


Mayo, 2019 | DOI: 10.1021/acs.langmuir.9b00457

Nanotecnología en Superficies y Plasma

3D core-multishell piezoelectric nanogenerators

A. Nicolas Filippin; Juan R.Sanchez-Valencia; Xabier Garcia-Casas; Victor Lopez-Flores; Manuel Macias-Montero; Fabian Frutos; Angel Barranco; Ana Borras
Nano Energy, 58 (2019) 476-483

The thin film configuration presents obvious practical advantages over the 1D implementation in energy harvesting systems such as easily manufacturing and processing, and long-lasting and stable devices. However, ZnO-based piezoelectric nanogenerators (PENGs) generally rely on the exploitation of single-crystalline nanowires because of their self-orientation in the c-axis direction and ability to accommodate long deformations resulting in high piezoelectric performance. Herein, we show an innovative approach to produce PENGs by combining polycrystalline ZnO layers fabricated at room temperature by plasma-assisted deposition with supported small-molecule organic nanowires (ONWs) acting as 1D scaffolds. Such hybrid nanostructures present convoluted core-shell morphology, formed by a single-crystalline organic nanowire conformally surrounded by a poly-crystalline ZnO shell and combine the organic core mechanical properties with the ZnO layer piezoelectric response. In a step forward towards the integration of multiple functions within a single wire, we have also developed ONW-Au-ZnO nanoarchitectures including a gold shell acting as inner electrode achieving output piezo-voltages up to 170 mV. The synergistic combination of functionalities in the ONW-Au-ZnO devices promotes an enhanced performance generating piezo-currents one order of magnitude larger than the ONW-ZnO nanowires and superior to the thin film nanogenerators for equivalent and higher thicknesses.


Abril, 2019 | DOI: 10.1016/j.nanoen.2019.01.047

Nanotecnología en Superficies y Plasma

Laser-induced coloration of ceramic tiles covered with magnetron sputtered precursor layers

Rico, VJ; Lahoz, R; Rey-Garcia, F; de Francisco, I; Gil-Rostra, J; Espinos, JP; de la Fuente, GF; Gonzalez-Elipe, AR
Journal of the American Ceramic Society, 102 (2019) 1589-1598

This paper reports a new methodology for the coloring of glazed ceramic tiles consisting of the near infrared pulsed laser processing of copper containing oxide coatings prepared by magnetron sputtering. As a second approach, the employ for the same purpose of a novel laser furnace technique is also described. Changing the laser parameters and using the laser furnace to treat the tiles at high temperature during irradiation has resulted in a wide color palette. The optical characterization of the modified tiles by UV-Vis spectroscopy has been complemented with their microstructural and compositional analysis by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Time Of Flight Secondary Ion Mass Spectrometry (TOF-SIMS). The chemical composition of the surface was obtained by X-ray Photoemission Spectroscopy (XPS) and its structure determined by X?ray diffraction (XRD). The chemical resistance was characterized by several tests following the norm ISO 10545-13. Color changes have been attributed to surface microstructural and chemical transformations that have been accounted for by simple models involving different ablation, melting, diffusion, and segregation/agglomeration phenomena depending on the laser treatments employed.


Abril, 2019 | DOI: 10.1111/jace.16022

Nanotecnología en Superficies y Plasma

CuxCo3-xO4 ultra-thin film as efficient anodic catalysts for anion exchange membrane water electrolysers

Lopez-Fernandez, E; Gil-Rostra, J; Espinos, JP; Gonzalez-Elipe, AR; Yubero, F; de Lucas-Consuegra, A
Journal of Power Sources, 415 (2019) 136-144

CuxCo3-xO4 ultra-thin films, deposited by magnetron sputtering at oblique angles have been used as anodic catalysts in anion exchange membrane water electrolysers. It has been demonstrated that the used deposition procedure provides porous and amorphous samples with a strict control of the total catalyst load and Co/Cu ratio. Electrocatalytic tests showed a maximum performance for the oxygen evolution reaction at Co/Cu atomic ratio around 1.8. The optimized anodic catalyst presented a long-term stability confirmed by accelerated lifetime tests together with the chemical surface analysis of the used samples. The effect of the crystallization of a single layer CuxCo3-xO4 and a multilayer (CuO/Co3O4)(n) anodic catalyst samples was also investigated. The observed loss of catalytic performance found in both cases may prove that a particular local chemical environment around the Co and Cu sites acts as an efficient catalytic site for the oxygen evolution reaction. A catalyst film with the optimum Co/Cu atomic ratio was incorporated into a Membrane Electrode Assembly, using a sputtered Ni film as cathode. Current density values up to 100 mA cm(-2) at 2.0 V were obtained in 1.0 M KOH electrolyte. Upon normalization by the amount of catalyst, this performance is one of the highest reported in literature.


Marzo, 2019 | DOI: 10.1016/j.jpowsour.2019.01.056

Reactividad de Sólidos - Tribología y Protección de Superficies

Microstructure, interfaces and properties of 3YTZP ceramic composites with 10 and 20 vol% different graphene-based nanostructures as fillers

Munoz-Ferreiro, C; Morales-Rodriguez, A; Rojas, TC; Jimenez-Pique, E; Lopez-Pernia, C; Poyato, R; Gallardo-Lopez, A
Journal of Alloys and Compounds, 777 (2019) 213-224

The graphene family comprises not only single layer graphene but also graphene-based nanomaterials (GBN), with remarkably different number of layers, lateral dimension and price. In this work, two of these GBN, namely graphene nanoplatelets (GNP) with n similar to 15-30 layers and few-layer graphene (FLG) with n < 3 layers have been evaluated as fillers in 3 mol% yttria stabilized tetragonal zirconia (3YTZP) ceramic composites. Composites with 10 and 20 vol% GNP or FLG have been fabricated by wet powder processing and spark plasma sintering (SPS) and the influence of the content and number of layers of the graphene-based filler has been assessed. For both graphene-based fillers, an intermediate zirconia oxycarbide has been detected in the grain boundaries. The lower stacking degree and much more homogeneous distribution of the FLG, revealed by transmission electron microscopy (TEM), can improve load transfer between the GBNs and the ceramic matrix. However, high FLG contents lower densification of the composites, due partly to the larger FLG interplanar spacing also estimated by TEM. The hardness (both Vickers and nanoindentation) and the elastic modulus decrease with increased GBN content and with improved graphene dispersion. The FLG greatly inhibit the crack propagation that occur perpendicular to their preferential orientation plane. The composites with thinner FLG have higher electrical conductivity than those with GNP. The highest electrical conductivity is achieved by composites with 20 vol% FLG in the direction perpendicular to the compression axis during sintering, sigma(perpendicular to) = 3400 +/- 500 Sm-1. 


Marzo, 2019 | DOI: 10.1016/j.jallcom.2018.10.336

Nanotecnología en Superficies y Plasma

Controlled thermolysis of MIL-101(Fe, Cr) for synthesis of FexOy/porous carbon as negative electrode and Cr2O3/porous carbon as positive electrode of supercapacitor

Farisabadi, A; Moradi, M; Hajati, S; Kiani, MA; Espinos, JP
Applied Surface Science, 469 (2019) 192-203

In the present study, two kinds of metal oxide/carbon nanocomposite were prepared through calcination of MIL-101(Fe, Cr). The morphological and structural properties of the specimens were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer, Emmett, and Teller analysis, energy dispersive Xray spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The electrode materials were also electrochemically investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques in 6 M KOH electrolyte. Because of synergistic effect of metal oxides and carbon, the obtained samples showed excellent performance; in a way that Cr2O3/C and Fe Oy/C showed high specific capacitance of 420 F g(-1) and 114 F g(-1) at current density of 2 A g(-1), respectively. The Cr2O3/C electrode also displayed high rate capability even at scan rate of 1500 mV s(-1). Moreover, we successfully developed an asymmetric supercapacitor in which Cr2O3/C served as positive electrode and Fe Oy/C served as negative electrode. The asymmetric device can deliver an energy density of 9.6 W h kg(-1) and power density of 8000 W kg(-1), with 93% capacitance retention after 3000 charge-discharge cycles. These outcomes show that the MOF-derived metal oxide/carbon composite can be regarded as a promising development for advanced electrode materials for applying in supercapacitors.


Marzo, 2019 | DOI: 10.1016/j.apsusc.2018.11.053

Nanotecnología en Superficies y Plasma

XPS primary excitation spectra of Zn 2p, Fe 2p, and Ce 3d from ZnO, α‐Fe2O3, and CeO2

Pauly, N.; Yubero, F.; Espinós, J.P.; Tougaard, S.
Surface and Interface Analysis, 51 (2019) 353-360

Metal oxides are important for current development in nanotechnology. X‐ray photoelectron spectroscopy(XPS) is a widely used technique to study the oxidation states of metals, and a basic understanding of the photoexcitation process is important to obtain the full information from XPS. We have studied core level excitations of Zn 2p, Fe 2p, and Ce 3d photoelectron emissions from ZnO, α‐Fe2O3, and CeO2. Using an effective energy‐differential XPS inelastic‐scattering cross section evaluated within the semiclassical dielectric response model for XPS, we analysed the experimental spectra to determine the corresponding primary excitation spectra, ie, the initial excitation processes. We find that simple emission (Zn 2p) as well as complex multiplet photoemission spectra (Fe 2p and Ce 3d) can be quantitatively analysed with our procedure. Moreover, for α‐Fe2O3, it is possible to use the software package CTM4XAS (Charge Transfer Multiplet program for X‐ray Absorption Spectroscopy) to calculate its primary excitation spectrum within a quantum mechanical model, and it was found to be in good agreement with the spectrum determined by analysis of the experiment.


Marzo, 2019 | DOI: 10.1002/sia.6587

Tribología y Protección de Superficies

The impact of photocatalytic Ag/TiO2 and Ag/N-TiO2 nanoparticles on human keratinocytes and epithelial lung cells

Rebleanu, D; Gaidau, C; Voicu, G; Constantinescu, CA; Sanchez, CM; Rojas, TC; Carvalho, S; Calin, M
Toxicology, 416 (2019) 30-43

The potential human health risks following the exposure to inorganic nanoparticles (NPs) is a very important issue for their application in leather finishing industry. The aim of our study was to investigate the cytotoxic effect of silver (Ag)/titanium dioxide (TiO2) NPs on human cells. Photocatalytic NPs were prepared by electrochemical deposition of Ag on the surface of TiO2 and nitrogen (N)-TiO2 NPs and, subsequently, physicochemical characterized. Then, a set of experiments have been performed to study the cytotoxicity and cell death mechanisms involved, the changes in cell morphology and the production of ROS induced in human keratinocytes (HaCaT) and human lung epithelial cells (A549) by exposure to NPs. Moreover, the changes in major signaling pathways and the inflammatory response induced by Ag/N-TiO2 NPs in A549 cells were investigated. The data showed that cell death by late apoptosis/necrosis is induced in cells as function of the dose and the type of NPs and is characterized by morphological changes and cytoskeletal disorganization and an increase in reactive oxygen species (ROS) production. The exposure of A549 cells to Ag/N-TiO2 NPs determine the activation of ERK1/2 MAP-kinase pathway and the release of pro-inflammatory mediators CXCL1, GM-CSF and MIF, known to be involved in the recruitment of circulating neutrophils and monocytes.


Marzo, 2019 | DOI: 10.1016/j.tox.2019.01.013

Materiales Nanoestructurados y Microestructura

Test of a He-3 target for transfer reactions in inverse kinematics

Carozzi, G; Valiente-Dobon, JJ; Gadea, A; Siciliano, M; Mengoni, D; Fernandez, A; Godinho, V; Hufschmidt, D; Di Nitto, A
Nuovo cimento c-colloquia and communications in physics, 42 (2019) 94

With the aim of studying exotic nuclei close to the proton dripline, an innovative He-3 target was produced and tested in a collaboration between the Materials Science Institute of Seville (Spain) and the Legnaro National Laboratories (Italy). The target was manufactured with a new technique that aims to reduce the costs while providing high quality targets. The target was tested at the Legnaro National Laboratories. The results of this test are presented in this contribution.


Marzo, 2019 | DOI: 10.1393/ncc/i2019-19094-9

Nanotecnología en Superficies y Plasma

Comparative studies on electrochemical energy storage of NiFe-S nanoflake and NiFe-OH towards aqueous supercapacitor

Naseri, M; Moradi, M; Hajati, S; Espinos, JP; Kiani, MA
Journal of Materials Science-Materials in Electronics, 30 (2019) 4499-4510

In this study, electrochemical energy storage performances of an efficient Ni-Fe sulfide and hydroxide supported on porous nickel foam are compared. X-ray diffraction (XRD), X-rayphotoelectron spectroscopy (XPS) and energy-dispersive X-ray spectrometer (EDS) results confirmed the formation of Ni-Fe-S and Ni-Fe-OH electrodes. In addition, Brunauer-Emmett Teller (BET) was used to determine the specific surface area of the prepared materials. Moreover, the morphologies were observed by scanning electron microscopy (SEM). The brilliant characteristics of Ni-Fe-S could be attributed to transport acceleration in electrolyte ions and electrons, occurrence of redox reactions as well as the higher conductivity of the sample. From stand point of comparison, the capacitance of Ni-Fe-S is more than that of Ni-Fe-OH. Therefore, the exchange of O2- with S2- in Ni-Fe-OH lattice obviously improves the electrochemical performance. The as-fabricated Ni-Fe sulfide electrode exhibits a tremendous specific capacitance of 884.9Fg(-1) at 1A g(-1). Furthermore, an assembled asymmetric supercapacitor device using the activated carbon as negative electrode and this smart configuration (Ni-Fe-S) as positive electrode also provided a maximum specific power and specific energy of 8000Wkg(-1), 37.9 Whkg(-1), respectively. Also, it shows cycling stability with 88.8% capacitance retention after 1700 cycles in aqueous electrolyte, demonstrating its potential application in the next-generation high-performance supercapacitors used for energy storage.


Marzo, 2019 | DOI: 10.1007/s10854-019-00738-x

Nanotecnología en Superficies y Plasma

Growth of nanocolumnar thin films on patterned substrates at oblique angles

Garcia-Valenzuela, A; Munoz-Pina, S; Alcala, G; Alvarez, R; Lacroix, B; Santos, AJ; Cuevas-Maraver, J; Rico, V; Gago, R; Vazquez, L; Cotrino, J; Gonzalez-Elipe, AR; Palmero, A
Plasma Processes and Polymers, 16 (2019) e1800135

The influence of one dimensional substrate patterns on the nanocolumnar growth of thin films deposited by magnetron sputtering at oblique angles is theoretically and experimentally studied. A well-established growth model has been used to study the interplay between the substrate topography and the thin film morphology. A critical thickness has been defined, below which the columnar growth is modulated by the substrate topography, while for thicknesses above, the impact of substrate features is progressively lost in two stages; first columns grown on taller features take over neighboring ones, and later the film morphology evolves independently of substrate features. These results have been experimentally tested by analyzing the nanocolumnar growth of SiO2 thin films on ion-induced patterned substrates.


Febrero, 2019 | DOI: 10.1002/ppap.201800135

Nanotecnología en Superficies y Plasma

Study of the Interface of the Early Stages of Growth under Quasi-Equilibrium Conditions of ZnO on Graphene/Cu and Graphite

Morales, C; Black, A; Urbanos, FJ; Granados, D; Mendez, J; del Campo, A; Yubero, F; Soriano, L
Advanced Materials Interfaces, 6 (2019) art. 1801689

The study of the early stages of growth of ZnO on graphene supported on Cu and on highly oriented pyrolytic graphite by means of reactive thermal evaporation of metallic Zn at room temperature is presented. This growth method allows to go in depth in the study of the fundamental interaction between ZnO and graphene at the interface in quasi-equilibrium conditions. Quantitative, chemical, and morphological analysis is performed using photoemission spectroscopy, atomic force, and scanning microscopies as experimental characterization techniques and factor analysis and inelastic peak shape analysis as modeling techniques. The growth of ZnO on a highly oriented pyrolytic graphite substrate is also studied using the same growth method for comparison. The results show that, in spite that the first atomic layer of both substrates is identical, the growth kinetics and morphology of the deposits are completely different. A model for the kinetics of the growth of ZnO on both substrates is proposed.


Febrero, 2019 | DOI: 10.1002/admi.201801689

Nanotecnología en Superficies y Plasma

Environmentally Tight TiO2-SiO2 Porous 1D-Photonic Structures

Garcia-Valenzuela, A; Lopez-Santos, C; Rico, V; Alvarez, R; Palmero, A; Gonzalez-Elipe, AR
Advanced Materials Interfaces, 6 (2019) art. 1801212

Although thin film porosity is the basis of many optical sensors, it can be deleterious for a stable optical behavior of passive optical elements due to the condensation of water and other vapors in their pores. This paper proposes a new strategy for the magnetron sputtering (MS) fabrication of environmentally tight SiO2-TiO2 porous multilayers. Thin films of these two oxides deposited in an oblique angle configuration (MS-OAD) present a nanocolumnar and highly porous nanostructure and, as a consequence, experience significant changes in their optical properties when exposed to water vapor. Similarly, the optical properties of Bragg reflectors and Bragg microcavities made of the stacking of porous and compact SiO2 and TiO2 thin films experience reversible changes when these 1D-photonic structures are exposed to water pressure. A key finding of this work is that a very thin capping layer of SiO2 deposited on the surface of porous SiO2 films in the stack, at the interlayer between the two oxides, efficiently seals the pores making the photonic structures environmentally tight. This capping layer approach is a useful strategy to incorporate porosity as an additional parameter to design the optical behavior of planar photonic structures while preserving optical and environmental stability.


Febrero, 2019 | DOI: 10.1002/admi.201801212

Materiales Ópticos Multifuncionales

Mechanism of Photoluminescence Intermittency in Organic-Inorganic Perovskite Nanocrystals

Galisteo-Lopez, JF; Calvo, ME; Rojas, TC; Miguez, H
ACS Applied Materials & Interfaces, 11 (4) (2019) 6344-6349

Lead halide perovskite nanocrystals have demonstrated their potential as active materials for optoelectronic applications over the past few years. Nevertheless, one issue that hampers their applicability has to do with the observation of photoluminescence intermittency, commonly referred to as "blinking", as in their inorganic counterparts. Such behavior, reported for structures well above the quantum confinement regime, has been discussed to be strongly related to the presence of charge carrier traps. In this work, we analyze the characteristics of this intermittency and explore the dependence on the surrounding atmosphere, showing evidence for the critical role played by the presence of oxygen. We discuss a possible mechanism in which a constant creation/annihilation of halide-related carrier traps takes place under light irradiation, with the dominant rate being determined by the atmosphere.


Febrero, 2019 | DOI: 10.1021/acsami.8b17122

Nanotecnología en Superficies y Plasma

Holmium doped fiber thermal sensing based on an optofluidic Fabry-Perot microresonator

Lahoz, F; Martin, IR; Soler-Carracedo, K; Caceres, JM; Gil-Rostra, J; Yubero, F
Journal of Luminescence, 206 (2019) 492-497

An optical temperature sensor suitable for label free liquid sensing has been designed and characterized. The sensor combines the photochemical stability of rare earth doped glasses and the high sensitivity of interferometric resonators. It is formed by a planar Eabry-Perot (FP) microcavity filled with the liquid to be monitored. A Ho3+ doped tapered optical fiber has been placed inside the microcavity surrounded by the fluid medium. An external laser is focused on the optical fiber inside the cavity to induce the luminescence of the Ho3+ ions, which couples to the FP optical resonances. The spectral position of the FP resonances is highly sensitive to the refractive index of the cavity medium. A second laser is co-aligned with the first one to locally heat the liquid medium around the optical fiber. An average blue shift of the FP resonances around 32 pm/degrees C is measured. The limit of detection of the laser induced heating of the liquid medium is about 0.3 degrees C in the biological temperature range. Alternatively, a hot-plate is used to heat the system. Interestingly, a red shift of the FP modes is observed with 75 pm/degrees C dependence and 0.12 degrees C limit of detection features.


Febrero, 2019 | DOI: 10.1016/j.jlumin.2018.10.103

Nanotecnología en Superficies y Plasma

An innovative approach for micro/nano structuring plasma polymer films

Thiry, D; Vinx, N; Aparicio, FJ; Moerman, D; Lazzaroni, R; Cossement, D; Snyders, R
Thin Solid Films, 672 (2019) 26-32

This work aims at presenting an innovative method for tailoring the morphology of functionalized plasma polymer films (PPF). The approach is based on the formation of a plasma polymer bilayer system in which the two layers differ by their chemical composition and cross-linking degree. As a case study, propanethiol-based plasma polymer films have been investigated. As revealed by a much higher S/C ratio than in the propanethiol precursor (i.e. 0.83 vs 0.33), it has been demonstrated that the bottom layer contains a large fraction of trapped sulfur-based molecules (e.g. H2S). When further covered by a denser PPF formed at higher energetic conditions, a three-dimensional morphological reorganization takes place giving rise to the micro/nano structuration of the organic material. The shape, the dimensions as well as the density of the generated structures are found to depend on the thickness of both coatings involved in the bilayer structure, offering a great flexibility for surface engineering. Annealing experiments unambiguously confirm the major role played by the sulfur-based trapped molecules for inducing the reshaping process. The whole set of data clearly paves the way for the development of an innovative approach for finely tailoring the morphology of functionalized PPF at the micro/nano scale.


Febrero, 2019 | DOI: 10.1016/j.tsf.2018.12.050

Tribología y Protección de Superficies

Influence of Al and Y content on the oxidation resistance of CrAlYN protective coatings for high temperature applications: New insights about the Y role

Rojas, TC; Dominguez-Meister, S; Brizuela, M; Sanchez-Lopez, JC
Journal of Alloys and Compounds, 777 (2019) 1172-1181

CrAlYN hard coatings with two different average Al contents: similar to 16 at.% and similar to 25 at.%, and Y concentration varying between 1.2 and 5.7 at.% were deposited by direct current reactive magnetron co-sputtering of mixed Cr-Al and Y targets on commercial M2 steel substrates. The samples were heated to 1000 degrees C in air during 2 h to study their oxidation resistance and thermal stability. The Y content is critical and the coatings present different behaviour depending on the Al content. The best oxidation resistance and thermal stability are obtained for the coating with similar to 16 at.% Al and 3.4 at.% Y. The initial film microstructure and the cubic phase (fcc-CrAlN) were retained, and a thin (Cr,Al)(2)O-3 oxide protective scale was formed. At lower Y content (1.2 at.%) iron, from the substrate crosses the coating, while a higher content (4.6 at.%) avoided the iron diffusion at the expense of a thicker oxide scale with new oxide phases. The coatings with higher Al content (similar to 25 at. %) were not thermally stable at 1000 degrees C. A good oxidation resistance was obtained for 2.6 at.% of Y although new phases (hcp-AlN and Cr-Fe) were formed. Higher amount of yttrium (similar to 5.7 at. %) led to the complete oxidation of the coating. 


Enero, 2019 | DOI: 10.1016/j.jallcom.2018.09.280

Nanotecnología en Superficies y Plasma

Isotope Labelling for Reaction Mechanism Analysis in DBD Plasma Processes

Navascues, P; Obrero-Perez, JM; Cotrino, J; Gonzalez-Elipe, AR; Gomez-Ramirez, A
Catalysts, 9(1) (2019) 45

Dielectric barrier discharge (DBD) plasmas and plasma catalysis are becoming an alternative procedure to activate various gas phase reactions. A low-temperature and normal operating pressure are the main advantages of these processes, but a limited energy efficiency and little selectivity control hinder their practical implementation. In this work, we propose the use of isotope labelling to retrieve information about the intermediate reactions that may intervene during the DBD processes contributing to a decrease in their energy efficiency. The results are shown for the wet reforming reaction of methane, using D2O instead of H2O as reactant, and for the ammonia synthesis, using NH3/D-2/N-2 mixtures. In the two cases, it was found that a significant amount of outlet gas molecules, either reactants or products, have deuterium in their structure (e.g., HD for hydrogen, CDxHy for methane, or NDxHy for ammonia). From the analysis of the evolution of the labelled molecules as a function of power, useful information has been obtained about the exchange events of H by D atoms (or vice versa) between the plasma intermediate species. An evaluation of the number of these events revealed a significant progression with the plasma power, a tendency that is recognized to be detrimental for the energy efficiency of reactant to product transformation. The labelling technique is proposed as a useful approach for the analysis of plasma reaction mechanisms.


Enero, 2019 | DOI: 10.3390/catal9010045



2018


Nanotecnología en Superficies y Plasma

Quantitative analysis of Yb 4d photoelectron spectrum of metallic Yb

Pauly, N; Yubero, F; Tougaard, S
Surface & Coatings Technology, 50 (2018) 1168-1173

The measured Yb 4d(3/2) intensity is larger than the Yb 4d(5/2) in X-ray photoelectron (XPS) emission of metallic Yb, which is unexpected. The shape and intensity of photoelectron peaks are strongly affected by extrinsic excitations due to electron transport out of the surface (including bulk and surface effects) and to intrinsic excitations due to the sudden creation of the static core hole. To quantitatively extract from experimental XPS the primary excitation spectrum (ie, the initial excitation process) of the considered transition, these effects must be included within the theoretical description. The combined effect of both extrinsic and intrinsic excitations can be described by an effective energy-differential inelastic electron scattering cross section for XPS evaluated by a dielectric response model with the dielectric function as only input. Then, using this cross section, a direct evaluation of the primary excitation spectrum is performed by standard peak shape analysis for thick homogeneous samples. We use this approach in the present paper to determine the Yb 4d photoemission spectrum for metallic Yb. We show that the unexpected larger intensity of Yb 4d(3/2) compared to 4d(5/2) can be fully accounted for by our model and that the total spectrum consists of a sum of symmetric primary excitation peaks.


Noviembre, 2018 | DOI: 10.1002/sia.6402

Nanotecnología en Superficies y Plasma

The Role of Surface Recombination on the Performance of Perovskite Solar Cells: Effect of Morphology and Crystalline Phase of TiO2 Contact

Idigoras, J; Contreras-Bernal, L; Cave, JM; Courtier, NE; Barranco, A; Borras, A; Sanchez-Valencia, JR; Anta, JA; Walker, AB
Advanced Materials Interfaces, 5 (2018) art. 1801076

Herein, the preparation of 1D TiO2 nanocolumnar films grown by plasma-enhanced chemical vapor deposition is reported as the electron selective layer (ESL) for perovskite solar devices. The impact of the ESL architecture (1D and 3D morphologies) and the nanocrystalline phase (anatase and amorphous) is analyzed. For anatase structures, similar power conversion efficiencies are achieved using an ESL either the 1D nanocolumns or the classical 3D nanoparticle film. However, lower power conversion efficiencies and different optoelectronic properties are found for perovskite devices based on amorphous 1D films. The use of amorphous TiO2 as electron selective contact produces a bump in the reverse scan of the current-voltage curve as well as an additional electronic signal, detected by impedance spectroscopy measurements. The dependence of this additional signal on the optical excitation wavelength used in the IS experiments suggests that it stems from an interfacial process. Calculations using a drift-diffusion model which explicitly considers the selective contacts reproduces qualitatively the main features observed experimentally. These results demonstrate that for a solar cell in which the contact is working properly the open-circuit photovoltage is mainly determined by bulk recombination, whereas the introduction of a "bad contact" shifts the balance to surface recombination.


Noviembre, 2018 | DOI: 10.1002/admi.201801076

Nanotecnología en Superficies y Plasma

Influence of irrigation conditions in the germination of plasma treated Nasturtium seeds

Molina, R; Lopez-Santos, C; Gomez-Ramirez, A; Vilchez, A; Espinos, JP; Gonzalez-Elipe, AR
Scientific Reports, 8 (2018) art. 16442

Plasma treatments had emerged as a useful technique to improve seed germination. In this work we investigate the influence of different irrigation conditions and plasma treatments on the germination of nasturtium seeds. During plasma treatment, seeds experience a progressive weight loss as a function of treatment time that has been associated to water release, a process that is more pronounced after longer plasma treatment times. Seeds treated for short times (<30 s) are able to germinate more efficiently than untreated specimen under hydric stress (drought conditions), while plasma treatments for longer times (up to 300 s) impaired germination independently on irrigation conditions. Characterization analysis of plasma treated seeds by FTIR-ATR, SEM/EDX and XPS showed that plasma treatment affected the chemical state of pericarp while, simultaneously, induced a considerable increase in the seeds water uptake capacity. The decrease in germination efficiency found after plasma treatment for long times, or for short times under optimum irrigation conditions, has been attributed to that the excess of water accumulated in the pericarp hampers the diffusion up to the embryo of other agents like oxygen which are deemed essential for germination.


Noviembre, 2018 | DOI: 10.1038/s41598-018-34801-0

Materiales Nanoestructurados y Microestructura

Nanoporous Pt-based catalysts prepared by chemical dealloying of magnetron-sputtered Pt-Cu thin films for the catalytic combustion of hydrogen

Giarratano, F; Arzac, GM; Godinho, V; Hufschmidt, D; de Haro, MCJ; Montes, O; Fernandez, A
Applied Catalysis B-Environmental, 235 (2018) 168-176

In this work, we prepared SiC-supported Pt-Cu thin films by magnetron sputtering for use as catalysts for the combustion of hydrogen under oxidizing conditions. We tested the catalysts as prepared and after chemical dealloying. A methodology is presented to fabricate catalytic thin films of a desired composition with tailored magnetron targets with lower Pt consumption. The deposition gas was changed to prepare columnar (Ar-deposited) and closed-porous (He-deposited) films to study the effect of the microstructure on the activity. The effect of composition was also studied for the columnar samples. The as-prepared Pt-Cu thin films showed significant activity only at temperatures higher than 100 °C. Dealloying permitted an increase in the activity to achieve near room-temperature activity. The dealloyed closed-porous He-deposited sample was the most active, being able to convert as much as 13.15 LH2·min−1 gPt−1 at 70 °C (Ea = 1 kJ mol−1). This sample was preferentially dealloyed on the surface, yielding an almost pure Pt shell (96% at. Pt) and a Cu-depleted interior (71% at. Pt). This compositional inhomogeneity enabled the sample to achieve enhanced activity compared to the Ar-deposited columnar sample (with similar initial composition, but uniformly dealloyed), probably due to the compressive surface lattice strain. The dealloyed closed-porous He-deposited sample was shown to be durable over five cycles.


Noviembre, 2018 | DOI: 10.1016/j.apcatb.2018.04.064

Tribología y Protección de Superficies

High-temperature oxidation of CrAlYN coatings: Implications of the presence of Y and type of steel

Rojas, TC; Dominguez-Meister, S; Brizuela, M; Sanchez-Lopez, JC
Surface & Coatings Technology, 354 (2018) 203-2013

Nanolayered CrAIN and CrAIYN/CrAIN (average contents of Al approximate to 25 at.% and Y approximate to 1.6 at. %) coatings are deposited on M2 and 316 steel substrates and heated to 1000 degrees C in air for 2 h to study their oxidation mechanism, the thermal stability and the reactive element (RE) effect of yttrium. CrAIN on M2 develops a Cr2O3/Al2O3 passivation layer that preserves in high degree the fcc-CrAIN structure however iron ions leave the substrate and travel to the surface along the column boundaries. The CrAIYN/CrAIN coatings deposited on steels are not stable at 1000 degrees C, and the initial fcc-CrAIN phase is partially transformed to hcp-Al(O)N and Cr-Fe phases (M2) and Cr2N and Al2O3 (316). The addition of Y changes the predominant scale growth direction. Inward oxygen diffusion becomes dominant but a reduction of the oxide scale thickness as compared to CrAIN is not observed. The advanced microstructural analysis made by transmission electron microscopy combined with electron energy loss spectroscopy determined that yttrium migrates mainly to the oxide scale (forming mixed oxides with substrate elements - V and Mo, either as dispersed particles or segregated at the grain boundaries) in M2, and to the oxide interface and column boundaries (forming Al-Y oxides and YN, respectively) in 316 steel. The benefits of addition of Y in improving the oxidation resistance are discussed comparatively with literature data. The RE effect of yttrium is thus observed to be dependent on the substrate, film architecture and composition.


Octubre, 2018 | DOI: 10.1016/j.surfcoat.2018.09.020

Tribología y Protección de Superficies

Adhesion enhancement of DLC hard coatings by HiPIMS metal ion etching pretreatment

Santiago, JA; Fernandez-Martinez, I; Wennberg, A; Molina-Aldareguia, JM; Castillo-Rodriguez, M; Rojas, TC; Sanchez-Lopez, JC; Gonzalez, MU; Garcia-Martin, JM; Li, H; Bellido-Gonzalez, V; Monclus, MA; Gonzalez-Arrabal, R
Surface & Coatings Technology, 349 (2018) 787-796

Poor adhesion is a recurrent problem for the wider use of diamond-like carbon (DLC) coatings in industrial applications. In this work, we investigate the effectiveness of high-power impulse magnetron sputtering (HiPIMS) metal ion etching to improve the adhesion of DLC coatings on high speed steel substrates. The influence of HiPIMS pretreatment parameters, the metal ion selection for the process and the addition of bonding layers on the adhesion properties were studied. Daimler-Benz and nanoscratch test methods were used to evaluate the adhesion. The elemental composition, morphology and microstructure of the samples were evaluated by EELS, SEM, AFM and HRTEM. In general, samples pretreated with HiPIMS metal ion etching withstand larger critical loads than those pretreated by conventional Ar + glow discharge and bonding layers. The pretreatment is proven to be very effective at removing surface contaminants and providing a gradual interface. The selection of Cr over Ti contributes to a significant improvement on the adhesion due to the reduction of the oxygen level at the interface thus ensuring an optimal coating-substrate contact and a more compliant structure, which prevents the delamination failure.


Septiembre, 2018 | DOI: 10.1016/j.surfcoat.2018.04.090

Nanotecnología en Superficies y Plasma

Sensing and biosensing with screen printed electrodes modified with nanostructured nickel oxide thin films prepared by magnetron sputtering at oblique angles

Salazar, P; Garcia-Garcia, FJ; Gonzalez-Elipe, AR
Electrochemistry Communications, 94 (2018) 5-8

This work reports about the sensing and biosensing applications of a novel screen printed electrode (SPE) modified by nanostructured nickel oxide thin films obtained by reactive magnetron sputtering under an oblique angle configuration. Using these films as electrodes we demonstrate their ability to detect hydrogen peroxide under neutral pH conditions. Furthermore, as a proof-of-concept, NiO-modified SPEs have been developed and their cholesterol biosensing properties determined by cyclic voltammetry and chronoamperometry.


Septiembre, 2018 | DOI: 10.1016/j.elecom.2018.07.020

Nanotecnología en Superficies y Plasma

Nanostructural Analysis of Porous Oblique Angle Deposited (OAD) Multilayer Systems by Grazing-Incidence Small-Angle X-Ray Scattering

Oliva-Ramirez, M; Lopez-Santos, C; Yubero, F; Gonzalez-Elipe, AR
Advanced Optical Materials, 5 (2018) 1800530

This work reports a thorough characterization analysis of various porous thin film multilayers by means of grazing-incidence small-angle X-ray scattering (GISAXS). Alternated TiO2/SiO2 nanocolumnar layers deposited at oblique angles are fabricated in slanted, chiral, and zig-zag configurations by rotating azimuthally the substrate from one layer to the next. Multilayer systems formed by the stacking of 3 and 15 alternant thin films of these two oxides are morphologically characterized by scanning electron microscopy (SEM) and structurally by GISAXS. This technique has provided a means to determine various vertical and lateral correlation lengths and to assess the anisotropic electron density distribution along the structural elements existing in the multilayers. This information can be systematically used to account for the actual arrangement of nanostructural elements in multilayer systems.


Septiembre, 2018 | DOI: 10.1002/admi.201800530

Materiales Ópticos Multifuncionales - Nanotecnología en Superficies y Plasma

Origin of Light-Induced Photophysical Effects in Organic Metal Halide Perovskites in the Presence of Oxygen

Anaya, M; Galisteo-Lopez, JF; Calvo, ME; Espinos, JP; Miguez, H
Journal of Physical Chemistry Letters, 9 (2018) 3891-3896

Herein we present a combined study of the evolution of both the photoluminescence (PL) and the surface chemical structure of organic metal halide perovskites as the environmental oxygen pressure rises from ultrahigh vacuum up to a few thousandths of an atmosphere. Analyzing the changes occurring at the semiconductor surface upon photoexcitation under a controlled oxygen atmosphere in an X-ray photoelectron spectroscopy (XPS) chamber, we can rationalize the rich variety of photophysical phenomena observed and provide a plausible explanation for light-induced ion migration, one of the most conspicuous and debated concomitant effects detected during photoexcitation. We find direct evidence of the formation of a superficial layer of negatively charged oxygen species capable of repelling the halide anions away from the surface and toward the bulk. The reported PL transient dynamics, the partial recovery of the initial state when photoexcitation stops, and the eventual degradation after intense exposure times can thus be rationalized.


Julio, 2018 | DOI: 10.1021/acs.jpclett.8b01830

Tribología y Protección de Superficies - Materiales Coloidales

Room temperature synthesis of water-dispersible Ln(3+):CeF3 (Ln = Nd, Tb) nanoparticles with different morphology as bimodal probes for fluorescence and CT imaging

Gonzalez-Mancebo, D; Becerro, AI; Rojas, TC; Olivencia, A; Corral, A; Balcerzyk, M; Cantelar, E; Cusso, F; Ocana, M
Journal of Colloid and Interface Science, 520 (2018) 134-144

The singular properties of lanthanide-based inorganic nanoparticles (NPs) has raised the attention of the scientific community in biotechnological applications. In particular, those systems with two or more functionalities are especially interesting. In this work, an effective and commercially attractive procedure has been developed that renders uniform, water-dispersible Ln(3+):CeF3 (Ln = Tb, Nd) NPs with different shapes and size. The method consists of the homogeneous precipitation, in a mixture of polyol and water, of cations and anions using precursors that allow the controlled release of the latter. The advantages of the reported method are related to the absence of surfactants, dispersing agents or corrosive precursors as well as to the room temperature of the process. The obtained Tb:CeF3 NPs produce an intense emission after excitation through the Ce-Tb energy transfer band located in the UV spectral region, thus being potentially useful as phosphors for in-vitro imaging purposes. On the other hand, the synthesized Nd:CeF3 NPs are good candidates for in-vivo imaging because their excitation and emission wavelengths lie in the biological windows. Finally, the excellent X-ray attenuation efficacy of the Nd:CeF(3)NPs is shown, which confers double functionality to this material as both luminescence bioprobe and contrast agent for X-ray computed-tomography. 


Junio, 2018 | DOI: 10.1016/j.jcis.2018.03.007

Materiales Nanoestructurados y Microestructura

Strong activation effect on a ru-co-c thin film catalyst for the hydrolysis of sodium borohydride

Arzac, GM; Paladini, M; Godinho, V; Beltran, AM; de Haro, MCJ; Fernandez, A
Scientific Reports, 8 (2018) art. 9755

In this work, we prepared a series of Ni foam supported Ru-Co, Ru-Co-B and Ru-Co-C catalysts in the form of columnar thin films by magnetron sputtering for the hydrolysis of sodium borohydride. We studied the activity and durability upon cycling. We found a strong activation effect for the Ru-Co-C sample which was the highest ever reported. This catalyst reached in the second cycle an activity 5 times higher than the initial (maximum activity 9310 ml.min(-1).g(CoRu)(-1) at 25 degrees C). Catalytic studies and characterization of the fresh and used samples permitted to attribute the strong activation effect to the following factors: (i) small column width and amorphous character (ii) the presence of Ru and (iii) dry state before each cycle. The presence of boron in the initial composition is detrimental to the durability. Our studies point out to the idea that after the first cycle the activity is controlled by surface Ru, which is the most active of the two metals. Apart from the activation effect, we found that catalysts deactivated in further cycles. We ascribed this effect to the loss of cobalt in the form of hydroxides, showing that deactivation was controlled by the chemistry of Co, the major surface metal component of the alloy. Alloying with Ru is beneficial for the activity but not for the durability, and this should be improved.


Junio, 2018 | DOI: 10.1038/s41598-018-28032-6

Nanotecnología en Superficies y Plasma

Growth of nanocolumnar porous TiO2 thin films by magnetron sputtering using particle collimators

Garcia-Valenzuela, A; Alvarez, R; Rico, V; Cotrino, J; Gonzalez-Elipe, AR; Palmero, A
Surface & Coatings Technology, 343 (2018) 172-177

The selective incorporation of deposition species with preferential directionality is analyzed during the growth of TiO2 thin films by magnetron sputtering. Using wisely-designed collimators, tilted nanocolumnar morphologies are grown in a ballistic deposition regime, i.e. when most deposition species arrive at the film surface along well-defined preferential directions, and also in a thermalized deposition regime, when these species follow an isotropic momentum distribution in the plasma gas. The obtained results suggest that the use of particle collimators may promote the growth of porous thin films even in the classical magnetron sputtering configuration, when the target and the substrate are parallel. General insights are given on this approach and, as a proof of concept, its principles applied for the synthesis of nanostructured films in a laboratory-size reactor.


Junio, 2018 | DOI: 10.1016/j.surfcoat.2017.09.039

Tribología y Protección de Superficies

Tribological properties of TiC/a-C:H nanocomposite coatings prepared via HiPIMS

Sanchez-Lopez, JC; Dominguez-Meister, S; Rojas, TC; Colasuonno, M; Bazzan, M; Patelli, A
Applied Surface Science, 440 (2018) 458-466

High power impulse magnetron sputtering (HiPIMS) technology has been employed to prepare TiC/a-C:H nanocomposite coatings from a titanium target in acetylene (C2H2) reactive atmospheres. Gas fluxes were varied from 1.3 to 4.4 sccm to obtain C/Ti ratios from 2 to 15 as measured by electron probe microanalysis (EPMA). X-ray diffraction and transmission electron microscopy demonstrate the presence of TiC nanocrystals embedded in an amorphous carbon-based matrix. The hardness properties decrease from 17 to 10 GPa as the carbon content increases. The tribological properties were measured using a pinon-disk tribometer in ambient air (RH = 30-40%) at 10 cm/s with 5 N of applied load against 6-mm 100Cr6 balls. The friction coefficient and the film wear rates are gradually improved from 0.3 and 7 x 10(-6) mm(3)/N m to 0.15 and 2 x 10(-7) mm(3)/N m, respectively, by increasing the C2H2 flux. To understand the tribological processes appearing at the interface and to elucidate the wear mechanism, microstructural and chemical investigations of the coatings were performed before and after the friction test. EPMA, X-ray photoelectron and electron energy-loss spectroscopies were employed to obtain an estimation of the fraction of the a-C:H phase, which can be correlated with the tribological behavior. Examination of the friction counterfaces (ball and track) by Raman microanalysis reveals an increased ordering of the amorphous carbon phase concomitant with friction reduction. The tribological results were compared with similar TiC/a-C(:H) composites prepared by the conventional direct current process. 


Mayo, 2018 | DOI: 10.1016/j.apsusc.2018.01.135

Materiales Nanoestructurados y Microestructura

The nanostructure of porous cobalt coatings deposited by magnetron sputtering in helium atmosphere

Lacroix, B; Godinho, V; Fernandez, A
Micron, 108 (2018) 49-54

In this work, (scanning) transmission electron microscopy has been used to study the nanostructure of porous cobalt coatings obtained by magnetron sputtering using helium as process gas. This nanostructure consists of closed pores of different nanometric size (about 4-20 nm) that are distributed all over a nanocrystalline Co matrix and filled with the deposition gas. Spatially resolved electron energy-loss spectroscopy analysis was applied to measure and map, with high lateral resolution, the relevant physical properties (density, pressure and He-K edge shift) of helium trapped inside these individual nanopores, in order to provide new insights about the growth mechanism involved in such systems. In particular, a coefficient of proportionality, C = 0.039 eV nm(3), between the blue shift of the He K-edge and the He density has been found. In addition, very high He densities (10-100 at./nm(3)) and pressures in the gigapascal range (0.05-5.0 GPa) have been measured. The linear dependence of these parameters as a function of the inverse radii obeying to the Laplace-Young law for most of the pores suggests that their formation during the coating's growth takes place in regime of elastic deformation of the Co matrix.


Mayo, 2018 | DOI: 10.1016/j.micron.2018.02.004

Materiales Nanoestructurados y Microestructura

Engineering of III-Nitride Semiconductors on Low Temperature Co-fired Ceramics

Manuel, JM; Jimenez, JJ; Morales, FM; Lacroix, B; Santos, AJ; Garcia, R; Blanco, E; Dominguez, M; Ramirez, M; Beltran, AM; Alexandrov, D; Tot, J; Dubreuil, R; Videkov, V; Andreev, S; Tzaneva, B; Bartsch, H; Breiling, J; Pezoldt, J; Fischer, M; Muller, J
Scientific Reports, 8 (2018) art. 6879

This work presents results in the field of advanced substrate solutions in order to achieve high crystalline quality group-III nitrides based heterostructures for high frequency and power devices or for sensor applications. With that objective, Low Temperature Co-fired Ceramics has been used, as a non-crystalline substrate. Structures like these have never been developed before, and for economic reasons will represent a groundbreaking material in these fields of Electronic. In this sense, the report presents the characterization through various techniques of three series of specimens where GaN was deposited on this ceramic composite, using different buffer layers, and a singular metal-organic chemical vapor deposition related technique for low temperature deposition. Other single crystalline ceramic-based templates were also utilized as substrate materials, for comparison purposes.


Mayo, 2018 | DOI: 10.1038/s41598-018-25416-6

Materiales Nanoestructurados y Microestructura

Microemulsion Assisted Sol-Gel Method as Approach to Load a Model Anticancer Drug inside Silica Nanoparticles for Controlled Release Applications

Jaramillo, N; Paucar, C; Fernandez, A; Negrete, CG; Garcia, C
Collid and Interface Science Communications, 24 (2018) 13-17

Silica nanoparticles are attractive carriers due to their improved safety and effectiveness in drug delivery. Silica nanoparticles were synthesized by using microemulsion assisted sol-gel method, and a model anticancer drug 5-fluorouracil (5-FU) was added to the silica precursor before hydrolysis and condensation reactions start. The obtained materials were characterized by Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR). Drug encapsulation within silica nanoparticles causes an increase in particle size. However, particle morphology is not affected. The drug release profile was obtained through high performance liquid chromatography (HPLC). The encapsulation approach showed to be effective for sustaining a continuous and increasing release during testing time (98 h). Further studies were performed to evaluate the cytotoxic effects of silica nanoparticles with loaded 5-FU on Chinese hamster ovary cells (CHO-K1). Materials are non-cytotoxic for all concentration tested (5-200 mu g/mL).


Mayo, 2018 | DOI: 10.1016/j.colcom.2018.03.002

Nanotecnología en Superficies y Plasma

In Vitro Comparative Study of Oxygen Plasma Treated Poly(Lactic-Co-Glycolic) (PLGA) Membranes and Supported Nanostructured Oxides for Guided Bone Regeneration Processes

Torres-Lagares, D; Castellanos-Cosano, L; Serrera-Figallo, MA; Lopez-Santos, C; Barranco, A; Rodriguez-Gonzalez-Elipe, A; Gutierrez-Perez, JL
Materials, 11 (2018) art. 752

(1) Background: The use of physical barriers to prevent the invasion of gingival and connective tissue cells into bone cavities during the healing process is called guided bone regeneration. The objective of this in-vitro study was to compare the growth of human osteoblasts on Poly(Lactic-co-Glycolic) (PLGA) membranes modified with oxygen plasma and Hydroxyapatite (HA), silicon dioxide (SiO2), and titanium dioxide (TiO2) composite nanoparticles, respectively. (2) Methods: All the membranes received a common treatment with oxygen plasma and were subsequently treated with HA nanostructured coatings (n = 10), SiO2 (n = 10) and TiO2 (n = 10), respectively and a PLGA control membrane (n = 10). The assays were performed using the human osteoblast line MG-63 acquired from the Center for Scientific Instrumentation (CIC) from the University of Granada. The cell adhesion and the viability of the osteoblasts were analyzed by means of light-field microphotographs of each condition with the inverted microscope Axio Observer A1 (Carl Zeiss). For the determination of the mitochondrial energy balance, the MitoProbe (TM) JC-1 Assay Kit was employed. For the determination of cell growth and the morphology of adherent osteoblasts, two techniques were employed: staining with phalloidin-TRITC and staining with DAPI. (3) Results: The modified membranes that show osteoblasts with a morphology more similar to the control osteoblasts follow the order: PLGA/PO2/HA > PLGA/PO2/SiO2 > PLGA/PO2/TiO2 > PLGA (p < 0.05). When analysing the cell viability, a higher percentage of viable cells bound to the membranes was observed as follows: PLGA/PO2/SiO2 > PLGA/PO2/HA > PLGA/PO2/TiO2 > PLGA (p < 0.05), with a better energy balance of the cells adhered to the membranes PLGA/PO2/HA and PLGA/PO2/SiO2. (4) Conclusion: The membrane in which osteoblasts show characteristics more similar to the control osteoblasts is the PLGA/PO2/HA, followed by the PLGA/PO2/SiO2.


Mayo, 2018 | DOI: 10.3390/ma11050752

Nanotecnología en Superficies y Plasma

Colorimetric energy sensitive scintillator detectors based on luminescent multilayer designs

Ferrer, FJ; Gil-Rostra, J; Gonzalez-Elipe, AR; Yubero, F
Sensors and Actuators A-Physical, 272 (2018) 217-222

In this work we present a new concept for energy sensitive radiation-beam scintillator detectors based on a luminescent multilayer design, where each layer within the stack consists of a rare-earth-doped highly transparent oxide. For a given type of particle beam (i.e., protons, a particles, etc.), its penetration depth, and therefore its energy loss at a particular buried layer, depends on its initial kinetic energy. Relying on this principle and since the intensity of the luminescent response of each layer and substrate should be proportional to the energy deposited by the radiation beam, we prove that a characteristic energy dependent color emission is obtained depending on both the phosphors integrated in the luminescent stack and on the primary energy and type of particle beam. Phosphor doping, emission efficiency, layer thickness, and multilayer structure design are key parameters to achieve a broad gamut in colorimetric response. The developed scintillators are designed to operate in a transmission geometry (light detection from the opposite side of the incident radiation) which is well suited for high energy particle detection in fields such as oncotherapy, space radiation, or of fusion studies. The principles of the method are illustrated with a case example typical of ion beam accelerators devoted to materials analysis. It is obtained that the kinetic energy of protons/alpha particle beams can be distinguished and evaluated with a sensitivity of 0.06/0.25 chromaticity units per MeV in the 0.7-2.0 MeV range. 


Abril, 2018 | DOI: 10.1016/j.sna.2018.01.062

Nanotecnología en Superficies y Plasma

Enhancing Moisture and Water Resistance in Perovskite Solar Cells by Encapsulation with Ultrathin Plasma Polymers

Idigoras, J; Aparicio, FJ; Contreras-Bemal, L; Ramos-Terron, S; Alcaire, M; Sanchez-Valencia, JR; Borras, A; Barranco, A; Anta, JA
ACS Applied Materials & Interfaces, 10 (2018) 11587-11594

A compromise between high power conversion efficiency and long-term stability of hybrid organic inorganic metal halide perovskite solar cells is necessary for their outdoor photovoltaic application and commercialization. Herein, a method to improve the stability of perovskite solar cells under water and moisture exposure consisting of the encapsulation of the cell with an ultrathin plasma polymer is reported. The deposition of the polymer is carried out at room temperature by the remote plasma vacuum deposition of adamantane powder. This encapsulation method does not affect the photovoltaic performance of the tested devices and is virtually compatible with any device configuration independent of the chemical composition. After 30 days under ambient conditions with a relative humidity (RH) in the range of 35-60%, the absorbance of encapsulated perovskite films remains practically unaltered. The deterioration in the photovoltaic performance of the corresponding encapsulated devices also becomes significantly delayed with respect to devices without encapsulation when vented continuously with very humid air (RH > 85%). More impressively, when encapsulated solar devices were immersed in liquid water, the photovoltaic performance was not affected at least within the first 60 s. In fact, it has been possible to measure the power conversion efficiency of encapsulated devices under operation in water. The proposed method opens up a new promising strategy to develop stable photovoltaic and photocatalytic perovskite devices.


Abril, 2018 | DOI: 10.1021/acsami.7b17824

Nanotecnología en Superficies y Plasma

Electrophoretic deposition of mixed copper oxide/GO as cathode and N-doped GO as anode for electrochemical energy storage

Jafari, EA; Moradi, M; Hajati, S; Kiani, MA; Espinos, JP
Electrochimica Acta, 268 (2018) 392-402

In this work, energy storage properties of mixed copper oxide wrapped by reduced graphene oxide and nitrogen-doped reduced graphene oxide were investigated. First, co-electrophoretic deposition technique was used to coat GO@CuO on nickel foam; followed by electrochemical phase transformation to rGO@CuxO. Electron spectroscopy analyses (XPS, REELS and UPS) confirm the phase transformation and electrochemical reduction. Then, an electrophoretic deposition was carried out for coating nitrogen-doped graphene oxide on nickel foam coupled to its electrochemical reduction to the NrGO. The cathode and anode performances were studied by galvanostatic charge-discharge, cyclic voltammetry and impedance spectroscopy. The rGO@CuxO and NrGO exhibit a favorable specific capacity of 267.2 and 332.6 C g(-1) at 2 A g(-1), respectively. High electrochemical activity and elimination of polymer binders with a maximum potential of 1.6 V are among the advantages of rGO@CuxO//NrGO electrochemical charge storage device. Furthermore, fabricated device provided a maximum specific power and specific energy of 11917.24 W kg(-1) and 14.15 Wh kg(-1), respectively, with 86% capacity retention after 2000 cycles.


Abril, 2018 | DOI: 10.1016/j.electacta.2018.02.122

Materiales para Bioingeniería y Regeneración Tisular

Copper-containing mesoporous bioactive glass promotes angiogenesis in an in vivo zebrafish model

Romero-Sanchez, LB; Mari-Beffa, M; Carrillo, P; Medina, MA; Diaz-Cuenca, A
Acta Biomaterialia, 68 (2018) 272-285

The osteogenic and angiogenic responses of organisms to the ionic products of degradation of bioactive glasses (BGs) are being intensively investigated. The promotion of angiogenesis by copper (Cu) has been known for more than three decades. This element can be incorporated to delivery carriers, such as BGs, and the materials used in biological assays. In this work, Cu-containing mesoporous bioactive glass (MBG) in the SiO2-CaO-P2O5compositional system was prepared incorporating 5% mol Cu (MBG-5Cu) by replacement of the corresponding amount of Ca. The biological effects of the ionic products of MBG biodegradation were evaluated on a well-known endothelial cell line, the bovine aorta endothelial cells (BAEC), as well as in an in vivo zebrafish (Danio rerio) embryo assay. The results suggest that ionic products of both MBG (Cu free) and MBG-5Cu materials promote angiogenesis. In vitro cell cultures show that the ionic dissolution products of these materials are not toxic and promote BAEC viability and migration. In addition, the in vivo assay indicates that both exposition and microinjection of zebrafish embryos with Cu free MBG material increase vessel number and thickness of the subintestinal venous plexus (SIVP), whereas assays using MBG-5Cu enhance this effect.


Marzo, 2018 | DOI: 10.1016/j.actbio.2017.12.032

Nanotecnología en Superficies y Plasma

Robust polarization active nanostructured 1D Bragg Microcavities as optofluidic label-free refractive index sensor

Oliva-Ramirez, M; Gil-Rostra, J; Yubero, F; Gonzalez-Elipe, AR
Sensors and Actuators B-Chemical, 256 (2018) 590-599

In this work we report the use of polarization active porous 1D Bragg microcavities (BM) prepared by physical vapor deposition at oblique angles for the optofluidic analysis of liquid solutions. These photonic structures consist of a series of stacked highly porous layers of two materials with different refractive indices and high birefringence. Their operational principle implies filling the pores with the analyzed liquid while monitoring with linearly polarized light the associated changes in optical response as a function of the solution refractive index. The response of both polarization active and inactive BMs as optofluidic sensors for the determination of glucose concentration in water solutions has been systematically compared. Different methods of detection, including monitoring the BM wave retarder behavior, are critically compared for both low and high glucose concentrations. Data are taken in transmission and reflection modes and different options explored to prove the incorporation of these nanostructured transducers into microfluidic systems and/or onto the tip of an optical fiber. This analysis has proven the advantages of the polarization active transducer sensors for the optofluidic analysis of liquids and their robustness even in the presence of light source instabilities or misalignments of the optical system used for detection.


Marzo, 2018 | DOI: 10.1016/j.snb.2017.10.060

Materiales Nanoestructurados y Microestructura

Biodegradabiliy of spherical mesoporous silica particles (MCM-41) in simulated body fluid (SBF)

Boccardi, E; Philippart, A; Beltran, AM; Schmidt, J; Liverani, L; Peukert, W; Boccaccini, AR
American Mineralogist, 103 (2018) 350-354

Mesoporous silica particles of type MCM-41 (Mobile Composition of Matter No. 41), exhibiting highly ordered mesoporosity (pores with diameter between 2 and 50 nm) and surface roughness, are developed and used as a functional coating on bioactive glass-based scaffolds for bone tissue engineering. The degradability and the mesostructure stability of these novel MCM-41 particles were evaluated. The particles are immersed in simulated body fluid (SBF) for up to 28 days at 37 degrees C, and the variation of the ordered porosity, surface characteristics, and chemical composition of the particles are assessed by SEM-EDX, HRTEM, FTIR, ICP-OES, and pH measurements. The results indicate that the MCM-41 particles are affected by immersion in SBF only during the first few days; however, the surface and the mesopore structure of the particles do not change further with increasing time in SBF. The pore channel diameter increased slightly, confirming the stability of the developed material. The release of dissolved Si-species, which reached a maximum of 260 mg SiO2 per gram of material, could play a key role in gene activation of osteoblast cells and in inducing new bone matrix formation. 


Marzo, 2018 | DOI: 10.2138/am-2018-6281

Nanotecnología en Superficies y Plasma

Dye Giant Absorption and Light Confinement Effects in Porous Bragg Microcavities

Oliva-Ramirez, M; Gil-Rostra, J; Simonsen, AC; Yubero, F; Gonzalez-Elipe, AR
ACS Photonics, 5 (2018) 984-991

This work presents a simple experimental procedure to probe light confinement effects in photonic structures. Two types of porous 1D Bragg microcavities with two resonant peaks in the reflection gap were prepared by physical vapor deposition at oblique angle configurations and then infiltrated with dye solutions of increasing concentrations. The unusual position shift and intensity drop of the transmitted resonant peak observed when it was scanned through the dye absorption band have been accounted for by the effect of the light trapped at their optical defect layer. An experimentally observed giant absorption of the dye molecules and a strong anomalous dispersion in the refractive index of the solution are claimed as the reasons for the observed variations in the Bragg microcavity resonant feature. Determining the giant absorption of infiltrated dye solutions is proposed as a general and simple methodology to experimentally assess light trapping effects in porous photonic structures.


Marzo, 2018 | DOI: 10.1021/acsphotonics.7b01283

Nanotecnología en Superficies y Plasma

In situ monitoring of the phenomenon of electrochemical promotion of catalysis

Espinos, JP; Rico, VJ; Gonzalez-Cobos, J; Sanchez-Valencia, JR; Perez-Dieste, V; Escudero, C; de Lucas-Consuegra, A; Gonzalez-Elipe, AR
Journal of Catalysis, 358 (2018) 27-34

In this work we investigate by in-situ near-ambient pressure photoemission (NAPP) spectroscopy the phenomenon of Electrochemical Promotion of Catalysis (EPOC). We studied the reduction and diffusion kinetics of alkaline ions in a solid electrolyte cell formed by a nickel electrode supported on K+-beta-alumina electrolyte. Experiments in ultra-high vacuum and in the presence of steam showed that the amount of potassium atoms supplied to the surface is probably affected by nickel electronic modifications induced by adsorbed OH- groups. It was also deduced that part of the segregated potassium would be adsorbed at inner interfaces where it would be inaccessible to the photoelectron analyzer. A migration mechanism of the promoter is proposed consisting in: (i) the electrochemical reduction of the alkali ions (potassium) at the Ni/solid electrolyte/gas interface; (ii) the spillover of potassium atoms onto the Ni gas-exposed surface; and (iii) the diffusion of potassium atoms to Ni inner grain boundary interfaces.


Febrero, 2018 | DOI: 10.1016/j.jcat.2017.11.027

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Self-Assembly of the Nonplanar Fe(III) Phthalocyanine Small-Molecule: Unraveling the Impact on the Magnetic Properties of Organic Nanowires

Filippin, AN; Lopez-Flores, V; Rojas, TC; Saghi, Z; Rico, VJ; Sanchez-Valencia, JR; Espinos, JP; Zitolo, A; Viret, M; Midgley, PA; Barranco, A; Borras, A
Chemistry of Materials, 30 (2018) 879-887

In this article we show for the first time the formation of magnetic supported organic nanowires (ONWs) driven by self-assembly of a nonplanar Fe(III) phthalocyanine chloride (FePcCl) molecule. The ONWs grow by a crystallization mechanism on roughness-tailored substrates. The growth methodology consists of a vapor deposition under low vacuum and mild temperature conditions. The structure, microstructure, and chemical composition of the FePcCl NWs are thoroughly elucidated and compared with those of Fe(II) phthalocyanine NWs by a consistent and complementary combination of advanced electron microscopies and X-ray spectroscopies. In a further step, we vertically align the NWs by conformal deposition of a SiO2 shell. Such orientation is critical to analyze the magnetic properties of the FePcCl and FePc supported NWs. A ferromagnetic behavior below 30 K with an easy axis perpendicular to the phthalocyanine plane was observed in the two cases with the FePcCl nanowires presenting a wider hysteresis. These results open the path to the fabrication of nanostructured one-dimensional small-molecule spintronic devices.


Febrero, 2018 | DOI: 10.1021/acs.chemmater.7b04515

Materiales para Bioingeniería y Regeneración Tisular

Nanostructured hybrid device mimicking bone extracellular matrix as local and sustained antibiotic delivery system

Borrego-Gonzalez, S; Romero-Sanchez, LB; Blazquez, J; Diaz-Cuenca, A
Microporous and Mesoporous Materials, 256 (2018) 165-176

A fluidic permeable and stable in wet media, MBG-NfGel, device consisting of a mesoporous ceramic embodied in a nanofibrillar biodegradable polymer has been processed using appropriate thermally induced phase separation (TIPS) processing variables of 5.4% (wt/v) gelatin in 50/50 water/ethanol (v/v) ratio. The device comprises high surface area mesoporous bioactive glass (MBG) microparticles within a fibrous matrix of 170 nm average diameter nanofibers gelatin, forming a meshwork of 0.2-1.6 mu m range voids. Gentamicin sulphate (GS) antibiotic high loading capacity and sustained release ability, as well as in vitro bioactivity and osteoprogenitor cells biocompatibility supports long-term antibacterial and bone growth stimulation properties. Antibiotic local delivery functionality in vitro of this device has been analysed and discussed in relation to other systems previously reported. The presented device properties as well as its industrial scalability potential, in terms of process reliability and absence of toxic chemical agents, low raw material biopolymer cost and immunogenicity, are other important advantages. These advantages rank MBG-NfGel device as a potential candidate to further development for application as local antibiotic device in bone surgery and therapy.


Enero, 2018 | DOI: 10.1016/j.micromeso.2017.08.010

Nanotecnología en Superficies y Plasma

Nickel/Copper Bilayer-modified Screen Printed Electrode for Glucose Determination in Flow Injection Analysis

Salazar, P.; Rico, V.; Gonzalez-Elipe, Agustin R.
Electroanalysis, 30 (2018) 187-193

This work reports about the performance of a Ni/Cu-modified screen printed electrodes (SPE/Ni/Cu), prepared by physical vapor deposition (PVD) in an oblique angle configuration (OAD), for non-enzymatic glucose sensing applications. SPE/Ni/Cu electrodes showed an excellent reversibility and a catalytic behavior for detection of glucose that were controlled by the diffusion of reactants up to the active sites at the electrode surface. The study with a flow injection analysis (FIA) setup of the main experimental variables affecting the detection process has shown that the developed electrode system had an excellent glucose sensitivity of 1.04AM(-1)cm(-2) (R-2:0.999), a linear response up to 1mM, a limit of detection of 0.33M and a time of analysis of ca. 30s per sample. The selectivity of the sensor was checked against various interferences, including ascorbic acid, uric acid, acetaminophen and other sugars, in all cases with excellent results. The feasibility of using this sensor for practical applications was successfully confirmed by determining the glucose concentration in different commercial beverages.


Enero, 2018 | DOI: 10.1002/elan.201700592

Nanotecnología en Superficies y Plasma

Microstructural engineering and use of efficient poison resistant Au-doped Ni-GDC ultrathin anodes in methane-fed solid oxide fuel cells

Garcia-Garcia, FJ; Yubero, F; Gonzalez-Elipe, AR; Lambert, RM
International Journal of Refractory Metals & Hard Materials, 43 (2018) 885-893

Ultrathin porous solid oxide fuel cell (SOFC) anodes consisting of nickel-gadolinia-dopedceria (Ni-GDC) cermets with a unique porous micro-columnar architecture with intimate contact between the GDC and the Ni phases were made by magnetron sputtering at an oblique deposition angle and characterised in detail by a variety of methods prior to use in hydrogen or methane-fuelled SOFCs. These Ni-GDC anodes exhibited excellent transport properties, were robust under thermal cycling and resistant to delamination from the underlying yttria-stabilised zirconia electrolyte. Similarly prepared Au-doped Ni-GDC anodes exhibited the same morphology, porosity and durability. The gold associated exclusively with the Ni component in which it was present as a surface alloy. Strikingly, whatever their treatment, a substantial amount of Ce3+ persisted in the anodes, even after operation at 800 degrees C under fuel cell conditions. With hydrogen as fuel, the un-doped and Au doped Ni-GDC anodes exhibited identical electrochemical performances, comparable to that of much thicker commercial state-of-the-art Ni-GDC anodes. However, under steam reforming conditions with CH4/H(2)0 mixtures the behaviour of the Au-doped Ni-GDC anodes were far superior, exhibiting retention of good power density and dramatically improved resistance to deactivation by carbon deposition. Thus two distinct beneficial effects contributed to overall performance: persistence of Ce3+ in the working anodes could induce a strong metal-support interaction with Ni that enhanced the catalytic oxidation of methane, while formation of a Ni Au surface alloy that inhibited carbonisation and poisoning of the active nickel surface. 


Enero, 2018 | DOI: 10.1016/j.ijhydene.2017.11.020



2017


Nanotecnología en Superficies y Plasma

Silver and gold nanoparticles in nanometric confined templates: synthesis and alloying within the anisotropic pores of oblique angle deposited films

Parra-Barranco, J., Sánchez-Valencia, J.R., Barranco, A., González-Elipe, A.R.
Nanotechnology, 28 (2017) 485602

In this work we have developed an infiltration methodology to incorporate metal nanoparticles (NPs) of controlled size and shape into the open voids available in oblique angle deposited thin films. These NPs exhibited well-defined surface plasmon resonances (SPRs). The nanometric confined space provided by their porous microstructure has been used as a template for the growth of anisotropic NPs with interesting SPR properties. The fabrication methodology has been applied for the preparation of films with embedded Ag and Au NPs with two associated plasmon resonance features that developed a dichroic behaviour when examined with linearly polarized light. A confined alloying process was induced by near IR nanosecond laser irradiation yielding bimetallic NPs with SPR features covering a large zone of the electromagnetic spectrum. The possibilities of the method for the tailored fabrication of a wide range colour palette based on SPR features are highlighted.


Diciembre, 2017 | DOI: 10.1088/1361-6528/aa92af

Nanotecnología en Superficies y Plasma

Micron-scale wedge thin films prepared by plasma enhanced chemical vapor deposition

Lopez-Santos, MC; Alvarez, R; Palmero, A; Borras, A; del Campo, RC; Holgado, M; Gonzalez-Elipe, AR
Plasma Processes and Polymers, 14 (2017) e1700043

Wedge-shaped materials are currently employed for optical analyses and sensing applications. In this paper, we present an easy to implement plasma enhanced chemical vapor deposition procedure to grow wedge-shaped thin films with controlled slope at the scale of few hundred microns. The method relies on the use of few tenths micron height obstacles to alter the laminar flow of precursor gas during deposition and is applied for the fabrication of wedge-shaped ZnO thin films. Local interference patterns, refractive index, and birefringence of the films have been measured with one micron resolution using a specially designed optical set-up. Their micro- and nano-structures have been characterized by means of scanning electron microscopy and theoretically reproduced by Monte Carlo calculations.


Diciembre, 2017 | DOI: 10.1002/ppap.201700043

Tribología y Protección de Superficies

Determination of the thickness of the embedding phase in 0D nanocomposites

Martinez-Martinez, D; Sanchez-Lopez, JC
Applied Surface Science, 421 (2017) 179-184

0D nanocomposites formed by small nanoparticles embedded in a second phase are very interesting systems which may show properties that are beyond those observed in the original constituents alone. One of the main parameters to understand the behavior of such nanocomposites is the determination of the separation between two adjacent nanoparticles, in other words, the thickness of the embedding phase. However, its experimental measurement is extremely complicated. Therefore, its evaluation is performed by an indirect approach using geometrical models. The ones typically used represent the nanoparticles by cubes or spheres. 
In this paper the used geometrical models are revised, and additional geometrical models based in other parallelohedra (hexagonal prism, rhombic and elongated dodecahedron and truncated octahedron) are presented. Additionally, a hybrid model that shows a transition between the spherical and tessellated models is proposed. Finally, the different approaches are tested on a set of titanium carbide/amorphous carbon (TiC/a-C) nanocomposite films to estimate the thickness of the a-C phase and explain the observed hardness properties. 


Noviembre, 2017 | DOI: 10.1016/j.apsusc.2016.12.081

Nanotecnología en Superficies y Plasma

Structural control in porous/compact multilayer systems grown by magnetron sputtering

Garcia-Valenzuela, A; Lopez-Santos, C; Alvarez, R; Rico, V; Cotrino, J; Gonzalez-Elipe, AR; Palmero, A
Nanotechnology, 28 (2017) 46

In this work we analyze a phenomenon that takes place when growing magnetron sputtered porous/compact multilayer systems by alternating the oblique angle and the classical configuration geometries. We show that the compact layers develop numerous fissures rooted in the porous structures of the film below, in a phenomenon that amplifies when increasing the number of stacked layers. We demonstrate that these fissures emerge during growth due to the high roughness of the porous layers and the coarsening of a discontinuous interfacial region. To minimize this phenomenon, we have grown thin interlayers between porous and compact films under the impingement of energetic plasma ions, responsible for smoothing out the interfaces and inhibiting the formation of structural fissures. This method has been tested in practical situations for compact TiO2/porous SiO2 multilayer systems, although it can be extrapolated to other materials and conditions.


Noviembre, 2017 | DOI: 10.1088/1361-6528/aa8cf4

Nanotecnología en Superficies y Plasma

Vapor and liquid optical monitoring with sculptured Bragg microcavities

Oliva-Ramirez, M; Gil-Rostra, J; Lopez-Santos, MC; Gonzalez-Elipe, AR; Yubero, F
Journal of Nanophotonics, 11 (2017) 046009

Sculptured porous Bragg microcavities (BMs) formed by the successive stacking of columnar SiO2 and TiO2 thin films with a zig-zag columnar microstructure are prepared by glancing angle deposition. These BMs act as wavelength-dependent optical retarders. This optical behavior is attributed to a self-structuration of the stacked layers involving the lateral association of nanocolumns in the direction perpendicular to the main flux of particles during the multilayer film growth, as observed by focused ion beam scanning electron microscopy. The retardance of these optically active BMs can be modulated by dynamic infiltration of their open porosity with vapors, liquids, or solutions with different refractive indices. The tunable birefringence of these nanostructured photonic systems has been successfully simulated with a simple model that assumes that each layer within the BMs stack has uniaxial birefringence. The sculptured BMs have been incorporated as microfluidic chips for optical transduction for label-free vapor and liquid sensing. Several examples of the detection performance of these chips, working either in reflection or transmission configuration, for the optical monitoring of vapor and liquids of different refractive indices and aqueous solutions of glucose flowing through the microfluidic chips are described.


Octubre, 2017 | DOI: 10.1117/1.JNP.11.046009

Materiales y Procesos Catalíticos de Interés Ambiental y Energético - Materiales Nanoestructurados y Microestructura

Towards Extending Solar Cell Lifetimes: Addition of a Fluorous Cation to Triple Cation-Based Perovskite Films

Salado, M; Fernandez, MA; Holgado, JP; Kazim, S; Nazeeruddin, MK; Dyson, PJ; Ahmad, S
Chemsuschem, 10 (2017) 3846-3853

Organohalide perovskites have emerged as highly promising replacements for thin-film solar cells. However, their poor stability under ambient conditions remains problematic, hindering commercial exploitation. The addition of a fluorous-functionalized imidazolium cation during the preparation of a highly stable cesium-based mixed perovskite material Cs-0.05(MA(0.15)FA(0.85))(0.95)Pb(I0.85Br0.15)(3) (MA= methylammonium; FA= formamidinium) has been shown to influence its stability. The resulting materials, which vary according to the amount of the fluorous-functionalized imidazolium cation present during fabrication, display a prolonged tolerance to atmospheric humidity (> 100 days) along with power conversion efficiencies exceeding 16%. This work provides a general route that can be implemented in a variety of perovskites and highlights a promising way to increase perovskite solar cell stability.


Octubre, 2017 | DOI: 10.1002/cssc.201700797

Tribología y Protección de Superficies - Materiales Coloidales

HoF3 and DyF3 Nanoparticles as Contrast Agents for High-Field Magnetic Resonance Imaging

Gonzalez-Mancebo, Daniel; Becerro, Ana I.; Rojas, T. Cristina; Garcia-Martin, Maria L.; de la Fuente, Jesus M.; Ocana, Manuel
Particle & particle systems characterization, 34 (2017) art. 1700116

Clinical contrast agents (CAs) currently used in magnetic resonance imaging (MRI) at low fields are less effective at high magnetic fields. The development of new CAs is mandatory to improve diagnostic capabilities of the new generation of high field MRI scanners. The purpose of this study is to synthesize uniform, water dispersible LnF3 (Ln = Ho, Dy) nanoparticles (NPs) and to evaluate their relaxivity at high magnetic field (9.4 T) as a function of size and composition. Two different types of HoF3 NPs are obtained by homogeneous precipitation in ethylene glycol at 120 °C. The use of holmium acetate as holmium precursor leads to rhombus-like nanoparticles, while smaller, ellipsoid-like nanoparticles are obtained when nitrate is used as the holmium salt. To explain this behavior, the mechanism of formation of both kinds of particles is analyzed in detail. Likewise, rhombus-like DyF3 nanoparticles are prepared following the same method as for the rhombus-like HoF3 nanoparticles. We have found, to the best of knowledge, the highest transverse relaxivity values at 9.4 T described in the literature for this kind of CAs. Finally, the LnF3 NPs have shown negligible cytotoxicity for C6 rat glioma cells for concentrations up to 0.1 mg mL−1.


Octubre, 2017 | DOI: 10.1002/ppsc.201700116

Materiales Nanoestructurados y Microestructura

Incorporation of Calcium Containing Mesoporous (MCM-41-Type) Particles in Electrospun PCL Fibers by Using Benign Solvents

Liverani, L.;Boccardi, E.; Beltrán, A.M.; Boccaccini, A.R.
Polymers, 9 (2017) 487

The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO2particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The main aims of the present work are both the optimization of the particle synthesis and the fabrication of composite fibers, obtained using benign solvents, suitable as drug delivery systems and scaffolds for soft tissue engineering applications. The optimized synthesis and characterization of calcium-containing MCM-41 particles are reported. Homogeneous bead-free composite electrospun mats were obtained by using acetic acid and formic acid as solvents; neat PCL electrospun mats were used as control. Initially, an optimization of the electrospinning environmental parameters, like relative humidity, was performed. The obtained composite nanofibers were characterized from the morphological, chemical and mechanical points of view, the acellular bioactivity of the composite nanofibers was also investigated. Positive results were obtained in terms of mesoporous particle incorporation in the fibers and no significant differences in terms of average fiber diameter were detected between the neat and composite electrospun fibers. Even if the Ca-containing MCM-41 particles are bioactive, this property is not preserved in the composite fibers. In fact, during the bioactivity assessment, the particles were released confirming the potential application of the composite fibers as a drug delivery system. Preliminary in vitro tests with bone marrow stromal cells were performed to investigate cell adhesion on the fabricated composite mats, the positive obtained results confirmed the suitability of the composite fibers as scaffolds for soft tissue engineering.


Octubre, 2017 | DOI: 10.3390/polym9100487

Nanotecnología en Superficies y Plasma

Enhanced green fluorescent protein in optofluidic Fabry-Perot microcavity to detect laser induced temperature changes in a bacterial culture

Lahoz, F; Martin, IR; Walo, D; Freire, R; Gil-Rostra, J; Yubero, F; Gonzalez-Elipe, AR
Applied Physics Letters, 111 (2017) 111103

Thermal therapy using laser sources can be used in combination with other cancer therapies to eliminate tumors. However, high precision temperature control is required to avoid damage in healthy surrounding tissues. Therefore, in order to detect laser induced temperature changes, we have used the fluorescence signal of the enhanced Green Fluorescent Protein (eGFP) over-expressed in an E. coli bacterial culture. For that purpose, the bacteria expressing eGFP are injected in a Fabry-Perot (FP) optofluidic planar microcavity. In order to locally heat the bacterial culture, external infrared or ultraviolet lasers were used. Shifts in the wavelengths of the resonant FP modes are used to determine the temperature increase as a function of the heating laser pump power. Laser induced local temperature increments up to 6-7 degrees C were measured. These results show a relatively easy way to measure laser induced local temperature changes using a FP microcavity and using eGFP as a molecular probe instead of external nanoparticles, which could damage/alter the cell. Therefore, we believe that this approach can be of interest for the study of thermal effects in laser induced thermal therapies. 


Septiembre, 2017 | DOI: 10.1063/1.4990870

Nanotecnología en Superficies y Plasma

High performance novel gadolinium doped ceria/yttria stabilized zirconia/nickel layered and hybrid thin film anodes for application in solid oxide fuel cells

Garcia-Garcia, FJ; Beltran, AM; Yubero, E; Gonzalez-Elipe, AR; Lambert, RM
Journal of Power Sources, 363 (2017) 251-259

Magnetron sputtering under oblique angle deposition was used to produce Ni-containing ultra thin film anodes comprising alternating layers of,gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) of either 200 nm or 1000 nm thickness. The evolution of film structure from initial deposition, through calcination and final reduction was examined by XRD, SEM, TEM and TOF-SIMS. After subsequent fuel cell usage, the porous columnar architecture of the two-component layered thin film anodes was maintained and their resistance to delamination from the underlying YSZ electrolyte was superior to that of corresponding single component Ni-YSZ and Ni-GDC thin films. Moreover, the fuel cell performance of the 200 nm layered anodes compared favorably with conventional commercially available thick anodes. The observed dependence of fuel cell performance on individual layer thicknesses prompted study of equivalent but more easily fabricated hybrid anodes consisting of simultaneously deposited Ni-GDC and Ni-YSZ, which procedure resulted in exceptionally intimate mixing and interaction of the components. The hybrids exhibited very unusual and favorable I-V characteristics, along with exceptionally high power densities at high currents. Their discovery is the principal contribution of the present work. 


Septiembre, 2017 | DOI: 10.1016/j.jpowsour.2017.07.085

Nanotecnología en Superficies y Plasma

In Vitro and in Vivo Study of Poly(Lactic-co-Glycolic) (PLGA) Membranes Treated with Oxygen Plasma and Coated with Nanostructured Hydroxyapatite Ultrathin Films for Guided Bone Regeneration Processes

Torres-Lagares, D; Castellanos-Cosano, L; Serrera-Figallo, MA; Garcia-Garcia, FJ; Lopez-Santos, C; Barranco, A; Elipe, ARG; Rivera-Jimenez, C; Gutierrez-Perez, JL
Polymers, 9 (2017) art. 410

The novelty of this study is the addition of an ultrathin layer of nanostructured hydroxyapatite (HA) on oxygen plasmamodified poly(lactic-co-glycolic) (PLGA) membranes (PO2) in order to evaluate the efficiency of this novel material in bone regeneration. Methods: Two groups of regenerative membranes were prepared: PLGA (control) and PLGA/PO2/HA (experimental). These membranes were subjected to cell cultures and then used to cover bone defects prepared on the skulls of eight experimental rabbits. Results: Cell morphology and adhesion of the osteoblasts to the membranes showed that the osteoblasts bound to PLGA were smaller and with a lower number of adhered cells than the osteoblasts bound to the PLGA/PO2/HA membrane (p < 0.05). The PLGA/PO2/HA membrane had a higher percentage of viable cells bound than the control membrane (p < 0.05). Both micro-CT and histological evaluation confirmed that PLGA/PO2/HA membranes enhance bone regeneration. A statistically significant difference in the percentage of osteoid area in relation to the total area between both groups was found. Conclusions: The incorporation of nanometric layers of nanostructured HA into PLGA membranes modified with PO2 might be considered for the regeneration of bone defects. PLGA/PO2/HA membranes promote higher osteosynthetic activity, new bone formation, and mineralisation than the PLGA control group.


Septiembre, 2017 | DOI: 10.3390/polym9090410

Nanotecnología en Superficies y Plasma

Optical properties and electronic transitions of zinc oxide, ferric oxide, cerium oxide, and samarium oxide in the ultraviolet and extreme ultraviolet

Pauly, N; Yubero, F; Espinos, JP; Tougaard, S
Applied Optics, 56 (2017) 6611-6621

Optical properties and electronic transitions of four oxides, namely zinc oxide, ferric oxide, cerium oxide, and samarium oxide, are determined in the ultraviolet and extreme ultraviolet by reflection electron energy loss spectroscopy using primary electron energies in the range 0.3 - 2.0 keV. This technique allows the evaluation of the optical response in these ultraviolet spectral regions of a thin layer of material, and the analysis is straightforward. It is performed within the dielectric response theory by means of the QUEELS-epsilon(k,omega)-REELS software developed by Tougaard and Yubero [Surf. Interface Anal. 36, 824 ( 2004)]. The method consists basically in the fitting of experimentally determined single-scattering electron energy loss cross sections with a parametric energy loss function of the corresponding material, to the one calculated within a dielectric response formalism. The obtained refractive index and extinction coefficients, as well as the identified electronic transitions are compared, when available, with previously published results. 


Agosto, 2017 | DOI: 10.1364/AO.56.006611

Materiales Nanoestructurados y Microestructura

The role of cobalt hydroxide in deactivation of thin film Co-based catalysts for sodium borohydride hydrolysis

Paladini, M; Arzac, GM; Godinho, V; Hufschmidt, D; de Haro, MCJ; Beltran, AM; Fernandez, A
Applied Catalysis B-Environmental, 210 (2017) 342-351

Deactivation of a Co catalyst prepared as thin film by magnetron sputtering was studied for the sodium borohydride (SB) hydrolysis reaction under different conditions. Under high SB concentration in single run experiments, the formation of a B-O passivating layer was observed after 1.5 and 24 h use. This layer was not responsible for the catalyst deactivation. Instead, a peeling-off mechanism produced the loss of cobalt. This peeling-off mechanism was further studied in cycling experiments (14 cycles) under low SB concentrations. Ex-situ study of catalyst surface after use and solid reaction products (precipitates) was performed by X-Ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The presence of cobalt hydroxide and oxyhydroxide was detected as major components on the catalyst surface after use and as precipitates in the supernatant solutions after washing. Cobalt borate, cobalt carbonate and oxycarbonate were also formed but in lesser amounts. These oxidized cobalt species were formed and further detached from the catalyst at the end of the reaction and/or during catalyst washing by decomposition of the unstable in-situ formed cobalt boride. Leaching of cobalt soluble species was negligible. Thin film mechanical detachment was also found but in a smaller extent. To study the influence of catalyst composition on deactivation processes, cycling experiments were performed with Co-B and Co-C catalysts, also prepared as thin films. We found that the deactivation mechanism proposed by us for the pure Co catalyst also occurred for a different pure Co (prepared at higher pressure) and the Co-B and Co-C samples in our experimental conditions. 


Agosto, 2017 | DOI: 10.1016/j.apcatb.2017.04.005

Nanotecnología en Superficies y Plasma

One-reactor plasma assisted fabrication of ZnO@TiO2 multishell nanotubes: assessing the impact of a full coverage on the photovoltaic performance

Filippin, Alejandro Nicolas; Macias-Montero, Manuel; Saghi, Zineb; Idigoras, Jesus; Burdet, Pierre; Sanchez-Valencia, Juan R.; Barranco, Angel; Migdley, Paul A.; Anta, Juan A.; Borras, Ana
Scientific Reports, 7 (2017) art 9621

This paper addresses the fabrication of vertically aligned ZnO@TiO2multishell nanotubes by a combined full vacuum-plasma approach at mild temperatures. The growth is carried out within the premises of a one-reactor approach, i.e. minimizing the number of vacuum chambers and sample transferences. In this way, the interface between ZnO and TiO2 is fully preserved from humidity thus increasing ZnO durability and stability. These nanostructures are studied by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy in STEM (EDX-STEM). High density one-dimensional arrays of these nanotubes formed on FTO substrates are applied as photoanode in a dye-sensitized solar cell (DSC). The evolution of the dye adsorption capacity and solar cells parameters are explored as a function of the crystallinity and thickness of the TiO2 shell. The results show the critical effect of a full coverage by TiO2 of ZnO core to explain the mixed results found in the literature.


Agosto, 2017 | DOI: 10.1038/s41598-017-09601-7

Nanotecnología en Superficies y Plasma

Surface chemistry and germination improvement of Quinoa seeds subjected to plasma activation

Gomez-Ramierez, A.; Lopez-Santos, C.; Cantos, M.; Garcia, J. L.; Molina, R.; Cotrino, J.; Espinos, J. P.; Gonzalez-Elipe, A. R.
Scientific Reports, 7 (2017) art. 5924

Plasma treatment is recognized as a suitable technology to improve germination efficiency of numerous seeds. In this work Quinoa seeds have been subjected to air plasma treatments both at atmospheric and low pressure and improvements found in germination rate and percentage of success. Seed water uptake by exposure to water vapor, although slightly greater for plasma treated seeds, did not justify the observed germination improvement. To identify other possible factors contributing to germination, the chemical changes experienced by outer parts of the seed upon plasma exposure have been investigated by X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM-EDX). XPS revealed that the outer layers of the Quinoa plasma treated seeds were highly oxidized and appeared enriched in potassium ions and adsorbed nitrate species. Simultaneously, SEM-EDX showed that the enrichment in potassium and other mineral elements extended to the seed pericarp and closer zones. The disappearance from the surface of both potassium ions and nitrate species upon exposure of the plasma treated seeds to water vapor is proposed as a factor favoring germination. The use of XPS to study chemical changes at seed surfaces induced by plasma treatments is deemed very important to unravel the mechanisms contributing to germination improvement.


Julio, 2017 | DOI: 10.1038/s41598-017-06164-5

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Plasma assisted deposition of single and multistacked TiO2 hierarchical nanotube photoanodes

Filippin, AN; Sanchez-Valencia, JR; Idigoras, J; Rojas, TC; Barranco, A; Anta, JA; Borras, A
Nanoscale, 9 (2017) 8133-8141

We present herein an evolved methodology for the growth of nanocrystalline hierarchical nanotubes combining physical vapor deposition of organic nanowires (ONWs) and plasma enhanced chemical vacuum deposition of anatase TiO2 layers. The ONWs act as vacuum removable 1D and 3D templates, with the whole process occurring at temperatures ranging from RT to 250 degrees C. As a result, a high density of hierarchical nanotubes with tunable diameter, length and tailored wall microstructures are formed on a variety of processable substrates as metal and metal oxide films or nanoparticles including transparent conductive oxides. The reiteration of the process leads to the development of an unprecedented 3D nanoarchitecture formed by stacking the layers of hierarchical TiO2 nanotubes. As a proof of concept, we present the superior performance of the 3D nanoarchitecture as a photoanode within an excitonic solar cell with efficiencies as high as 4.69% for a nominal thickness of the anatase layer below 2.75 mu m. Mechanical stability and straightforward implementation in devices are demonstrated at the same time. The process is extendable to other functional oxides fabricated by plasma-assisted methods with readily available applications in energy harvesting and storage, catalysis and nanosensing.


Julio, 2017 | DOI: 10.1039/c7nr00923b

Nanotecnología en Superficies y Plasma

Low-Temperature Plasma Processing of Platinum Porphyrins for the Development of Metal Nanostructured Layers

Filippin, AN; Sanchez-Valencia, JR; Idigoras, J; Macias-Montero, M; Alcaire, M; Aparicio, FJ; Espinos, JP; Lopez-Santos, C; Frutos, F; Barranco, A; Anta, JA; Borras, A
Advanced Materials Interfaces, 4 (2017) 1601233

This article establishes the bases for a vacuum and plasma supported methodology for the fabrication at mild temperatures of nanostructured platinum in the form of porous layers and nanocolumns using platinum octaethylporphyrin as precursor. In addition, the application of these materials as tunable optical filters and nano-counterelectrodes is proved. On one hand, the transparency in the ultraviolet-visible-near infrared range can be adjusted precisely between 70% and 1% by tuning the deposition and processing conditions, obtaining a high spectral planarity. Deviations of the spectra from an ideal flat filter are below 4%, paving the way to the fabrication of neutral density filters. The transparency limit values yield a sheet resistivity of approximate to 1350 and 120 Omega square(-1), respectively. On the other hand, the catalytic properties of the nanostructures are further demonstrated by their implementation as counterelectrodes of excitonic solar cells surpassing the performance of commercial platinum as counterelectrode in a 20% of the overall cell efficiency due to simultaneous enhancement of short-circuit photocurrent and open-circuit photovoltage. One of the most interesting features of the developed methodology is its straightforward application to other metal porphyrins and phthalocyanines readily sublimable under mild vacuum and temperature conditions.


Julio, 2017 | DOI: 10.1002/admi.201601233

Nanotecnología en Superficies y Plasma

Formation of Subsurface W5+ Species in Gasochromic Pt/WO3 Thin Films Exposed to Hydrogen

Castillero, Pedro; Rico-Gavira, Victor; Lopez-Santos, Carmen; Barranco, Angel; Perez-Dieste, Virginia; Escudero, Carlos; Espinos, Juan P.; Gonzalez-Elipe, Agustin R.
Journal of Physical Chemistry C, 121 (2017) 15719-15727

M/WO3 (M = Pt, Pd) systems formed by a porous WO3 thin film decorated by metal nanoparticles are known for their reversible coloring upon exposure to H2 at room temperature. In this work, this gasochromic behavior is investigated in situ by means of near-ambient photoemission (NAPP). Pt/WO3 systems formed by very small Pt nanoparticles (10 ± 1 nm average size) incorporated in the pores of nanocolumnar WO3 thin films prepared by magnetron sputtering at an oblique angle have been exposed to a small pressure of hydrogen at ambient temperature. The recorded UV–vis transmission spectra showed the reversible appearance of a very intense absorption band responsible for the blue coloration of these gasochromic films. In an equivalent experiment carried out in the NAPP spectrometer, W 4f, O 1s, Pt 4f, and valence band photoemission spectra have been recorded at various photon energies to follow the evolution of the reduced tungsten species and hydroxyl groups formed upon film exposure to hydrogen. The obtained results are compared with those of a conventional X-ray photoemission study after hydrogen exposure between 298 and 573 K. As investigated by NAPP, the gasochromic behavior at 298 K is accounted for by a reaction scheme in which hydrogen atoms resulting from the dissociation of H2 onto the Pt nanoparticles are spilt over to the WO3 substrate where they form surface OH–/H2O species and subsurface W5+ cations preferentially located in buried layers of the oxide network.


Julio, 2017 | DOI: 10.1021/acs.jpcc.7b03385

Nanotecnología en Superficies y Plasma

A compact and portable optofluidic device for detection of liquid properties and label-free sensing

Lahoz, F; Martin, IR; Walo, D; Gil-Rostra, J; Yubero, F; Gonzalez-Elipe, AR
Journal of Physics D: Applied Physics, 50 (2017) 21

Optofluidic lasers have been widely investigated over the last few years mainly because they can be easily integrated in sensor devices. However, high power pulse lasers arc required as excitation sources, which, in practice, limit the portability of the system. Trying to overcome some of these limitations, in this paper we propose the combined use of a small CW laser with a Fabry-Perot optofluidic planar microcavity showing high sensitivity and versatility for detection of liquid properties and label-free sensing. Firstly, a fluorescein solution in ethanol is used to demonstrate the high performances of the FP microcavity as a temperature sensor both in the laser (high pump power above laser threshold) and in the fluorescence (low pump power) regimes. A shift in the wavelength of the resonant cavity modes is used to detect changes in the temperature and our results show that high sensitivities could be already obtained using cheap and portable CW diode lasers. In the second part of the paper, the demonstration of this portable device for label-free sensing is illustrated under low CW pumping. The wavelength positions of the optolluidic resonant modes are used to detect glucose concentrations in water solutions using a protein labelled with a fluorescent dye as the active medium.


Junio, 2017 | DOI: 10.1088/1361-6463/aa6cdd

Nanotecnología en Superficies y Plasma

Impact of moisture on efficiency-determining electronic processes in perovskite solar cells

Salado, Manuel; Contreras-Bernal, Lidia; Calio, Laura; Todinova, Anna; Lopez-Santos, Carmen; Ahmad, Shahzada; Borras, Ana; Idigoras, Jesus; Anta, Juan A.
Journal of Materials Chemistry A, 5 (2017) 10917-10927

Moisture-induced degradation in perovskite solar cells was thoroughly investigated by structural (SEM, EDS, XRD and XPS) and device characterization (impedance and intensity modulated photocurrent spectroscopy) techniques. Both the influence of the perovskite composition and the nature of the hole selective material were analyzed. The degradation rate was found to be significantly slower for mixed perovskites and P3HT-based devices. However, for a fixed degradation degree (defined as a 50% drop from the initial photocurrent), all configurations show similar features in small-perturbation analysis. Thus, a new mid-frequency signal appears in the impedance response, which seems to be related to charge accumulation at the interfaces. In addition, faster recombination, with a more important surface contribution, and slower transport were clearly inferred from our results. Both features can be associated with the deterioration of the contacts and the formation of a higher number of grain boundaries.


Junio, 2017 | DOI: 10.1039/c7ta02264f

Nanotecnología en Superficies y Plasma

In Situ Determination of the Water Condensation Mechanisms on Superhydrophobic and Superhydrophilic Titanium Dioxide Nanotubes

Macias-Montero, Manuel; Lopez-Santos, Carmen; Nicolas Filippin, A.; Rico, Victor J.; Espinos, Juan P.; Fraxedas, Jordi; Perez-Dieste, Virginia; Escudero, Carlos; Gonzalez-Elipe, Agustin R.; Borras, Ana
Langmuir, 33 (2017) 6449-6456

One-dimensional (1D) nanostructured surfaces based on high-density arrays of nanowires and nanotubes of photoactive titanium dioxide (TiO2) present a tunable wetting behavior from superhydrophobic to superhydrophilic states. These situations are depicted in a reversible way by simply irradiating with ultraviolet light (superhydrophobic to superhydrophilic) and storage in dark. In this article, we combine in situ environmental scanning electron microscopy (ESEM) and near ambient pressure photoemission analysis (NAPP) to understand this transition. These experiments reveal complementary information at microscopic and atomic level reflecting the surface wettability and chemical state modifications experienced by these 1D surfaces upon irradiation. We pay special attention to the role of the water condensation mechanisms and try to elucidate the relationship between apparent water contact angles of sessile drops under ambient conditions at the macroscale with the formation of droplets by water condensation at low temperature and increasing humidity on the nanotubes surfaces. Thus, for the as-grown nanotubes, we reveal a metastable and superhydrophobic Cassie state for sessile drops that tunes toward water dropwise condensation at the microscale compatible with a partial hydrophobic Wenzel state. For the UV-irradiated surfaces, a filmwise wetting behavior is observed for both condensed water and sessile droplets. NAPP analyses show a hydroxyl accumulation on the as-grown nanotubes surfaces during the exposure to water condensation conditions, whereas the water filmwise condensation on a previously hydroxyl enriched surface is proved for the superhydrophilic counterpart.


Junio, 2017 | DOI: 10.1021/acs.langmuir.7b00156

Nanotecnología en Superficies y Plasma

About the enhancement of chemical yield during the atmospheric plasma synthesis of ammonia in a ferroelectric packed bed reactor

Gomez-Ramirez, Ana; Montoro-Damas, Antonio M.; Cotrino, Jose; Lambert, Richard M.; Gonzalez-Elipe, Agustin R.
Plasma Processes and Polymers, 14 (2017) e1600081

Plasma reactions offer an attractive alternative route for the synthesis of a variety of valuable chemical compounds. Here we investigate the parameters that determine the efficiency of ammonia synthesis in a ferroelectric packed bed dielectric barrier discharge (DBD) reactor. The effects of varying the operating frequency, the size of the ferroelectric pellets and the inter-electrode distance have been systematically studied. Under optimised conditions nitrogen conversions in excess of 7% were achieved, higher than those previously obtained using DBD reactors. These findings are discussed with respect to variations in the electrical characteristics of the reactor under operating conditions and in the light of emission spectra obtained as a function of reactant flow rates. These encouraging results signpost future developments that could very substantially improve the efficiency of ammonia synthesis by means of DBD technology.


Junio, 2017 | DOI: 10.1002/ppap.201600081

Materiales para Bioingeniería y Regeneración Tisular

High surface area biopolymeric-ceramic scaffolds for hard tissue engineering

Romero-Sanchez, LB; Borrego-Gonzalez, S; Diaz-Cuenca, A
Biomedical Physics & Engineering Express, 3 (2017) art UNSP 035012

The development of scaffolds mimicking native bone tissue composition and structure is a challenge in bone tissue engineering. 3D scaffolds with both an interconnected macropore structure and nanotextured surfaces are required. However, 3D scaffolds processed by microfabrication usually lack of nanotextured surface, while nanotextured materials generated by bottom-up nanofabrication are difficult to process conforming scaffolds having well interconnected microsized cavities. In this work, the processing of reticulated (macropore interconnected) structures using nanostructured precursors has been performed to improve the mechanical properties of the scaffolds. The application of a fibrillar collagen coating, using less than 1 wt% collagen per scaffold, has allow a significant increase of the compressive strength while preserving a high surface area and nanopore accessibility. Besides, the fibrillar nanostructured collagen coating promotes hydroxyapatite mineralization. Two different collagen-coating procedures are applied showing interesting differences in terms of mechanical performance.


Junio, 2017 | DOI: 10.1088/2057-1976/aa7001

Nanotecnología en Superficies y Plasma - Materiales y Procesos Catalíticos de Interés Ambiental y Energético

Critical Role of Oxygen in Silver-Catalyzed Glaser-Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

Orozco, N; Kyriakou, G; Beaumont, SK; Sanz, JF; Holgado, JP; Taylor, MJ; Espinos, JP; Marquez, AM; Watson, DJ; Gonzalez-Elipe, AR; Lambert, RM
ACS Catalysis, 7 (2017) 3113-3120

The essential role of oxygen in enabling heterogeneously catalyzed Glaser–Hay coupling of phenylacetylene on Ag(100) was elucidated by STM, laboratory and synchrotron photoemission, and DFT calculations. In the absence of coadsorbed oxygen, phenylacetylene formed well-ordered dense overlayers which, with increasing temperature, desorbed without reaction. In striking contrast, even at 120 K, the presence of oxygen led to immediate and complete disruption of the organic layer due to abstraction of acetylenic hydrogen with formation of a disordered mixed layer containing immobile adsorbed phenylacetylide. At higher temperatures phenylacetylide underwent Glaser–Hay coupling to form highly ordered domains of diphenyldiacetylene that eventually desorbed without decomposition, leaving the bare metal surface. DFT calculations showed that, while acetylenic H abstraction was otherwise an endothermic process, oxygen adatoms triggered a reaction-initiating exothermic pathway leading to OH(a) + phenylacetylide, consistent with the experimental observations. Moreover, it was found that, with a solution of phenylacetylene in nonane and in the presence of O2, Ag particles catalyzed Glaser–Hay coupling with high selectivity. Rigorous exclusion of oxygen from the reactor strongly suppressed the catalytic reaction. Interestingly, too much oxygen lowers the selectivity toward diphenyldiacetylene. Thus, vacuum studies and theoretical calculations revealed the key role of oxygen in the reaction mechanism, subsequently borne out by catalytic studies with Ag particles that confirmed the presence of oxygen as a necessary and sufficient condition for the coupling reaction to occur. The direct relevance of model studies to a mechanistic understanding of coupling reactions under conditions of practical catalysis was reaffirmed.


Mayo, 2017 | DOI: 10.1021/acscatal.7b00431

Nanotecnología en Superficies y Plasma

Non-enzymatic hydrogen peroxide detection at NiO nanoporous thin film-electrodes prepared by physical vapor deposition at oblique angles

Salazar, Pedro; Rico, Victor; Gonzalez-Elipe, Agustin R.
Electrochimica Acta, 235 (2017) 534-542

In this work we report a non-enzymatic sensor for hydrogen peroxide (H2O2) detection based on nanostructured nickel thin films prepared by physical vapor deposition at oblique angles. Porous thin films deposited on ITO substrates were characterized by X-ray diffraction analysis, scanning electron microcopy (SEMs), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques such as Cyclic Voltammetry (CV) and Constant Potential Amperometry (CPA). The microstructure of the thin films consisted of inclined and separated Ni nanocolumns forming a porous thin layer of about 500 nm thickness. Prior to their use, the films surface was electrochemically modified and the chemical state studied by CV and XPS analysis. These techniques also showed that Ni2+/Ni3+ species were involved in the electrochemical oxidation and detection of H2O2 in alkaline medium. Main analytical parameters such as sensitivity (807 mA M(-1)cm(-2)), limit of detection (3.22 mu M) and linear range (0.011-2.4 mM) were obtained under optimal operation conditions. Sensors depicted an outstanding selectivity and a high stability and they were successfully used to determine H2O2 concentration in commercial antiseptic solutions.


Mayo, 2017 | DOI: 10.1016/j.electacta.2017.03.087

Nanotecnología en Superficies y Plasma

Energy-Sensitive Ion- and Cathode-Luminescent Radiation-Beam Monitors Based on Multilayer Thin-Film Designs

Gil-Rostra, Jorge; Ferrer, Francisco J.; Pedro Espinos, Juan; Gonzalez-Elipe, Agustin R.; Yubero, Francisco
ACS Applied Materials & Interfaces, 9 (2017) 16313-16320

A multilayer luminescent design concept is presented to develop energy sensitive radiation-beam monitors on the basis of colorimetric analysis. Each luminescent layer within the stack consists of rare-earth-doped transparent oxides of optical quality and a characteristic luminescent emission under excitation with electron or ion beams. For a given type of particle beam (electron, protons, alpha particles, etc.), its penetration depth and therefore its energy loss at a particular buried layer within the multilayer stack depend on the energy of the initial beam. The intensity of the luminescent response of each layer is proportional to the energy deposited by the radiation beam within the layer, so characteristic color emission will be achieved if different phosphors are considered in the layers of the luminescent stack. Phosphor doping, emission efficiency, layer thickness, and multilayer structure design are key parameters relevant to achieving a broad colorimetric response. Two case examples are designed and fabricated to illustrate the capabilities of these new types of detector to evaluate the kinetic energy of either electron beams of a few kilo-electron volts or a particles of alpha few mega-electron volts.


Mayo, 2017 | DOI: 10.1021/acsami.7b01175

Nanotecnología en Superficies y Plasma

1-dimensional TiO2 nano-forests as photoanodes for efficient and stable perovskite solar cells fabrication

Salado, M; Oliva-Ramirez, M; Kazim, S; Gonzalez-Elipe, AR; Ahmad, S
Nano Energy, 35 (2017) 215-222

During the last years, perovskite solar cells have gained increasing interest among the photovoltaic community, in particularly after reaching performances at par with mature thin film based PV. This rapid evolution has been fostered by the compositional engineering of perovskite and new device architectures. In the present work, we report the fabrication of perovskite solar cells based on highly ordered 1-dimensional vertically oriented TiO2 nano-forests. These vertically oriented porous TiO2 photoanodes were deposited by physical vapor deposition in an oblique angle configuration, a method which is scalable to fabricate large area devices. Mixed (MA0.15FA0.85)Pb(I0.85Br0.15)3 or triple cation Cs0.05(MA0.15FA0.85)0.95Pb(I0.85Br0.15)3 based perovskites were then infiltrated into these 1-dimensional nanostructures and power conversion efficiencies of 16.8% along with improved stability was obtained. The devices fabricated using 1D-TiO2 were found to be more stable compare to the classical 3-dimensional TiO2 photoanodes prepared by wet chemistry. These 1-D photoanodes will be of interest for scaling up the technology and in other opto-electrical devices as they can be easily fabricated utilizing industrially adapted methodologies.


Mayo, 2017 | DOI: 10.1016/j.nanoen.2017.03.034

Nanotecnología en Superficies y Plasma

Improving the pollutant removal efficiency of packed-bed plasma reactors incorporating ferroelectric components

Gomez-Ramirez, Ana; Montoro-Damas, Antonio M.; Rodriguez, Miguel A.; Gonzalez-Elipe, Agustin R.; Cotrino, Jose
Chemical Engineering Journal, 314 (2017) 311-319

In this work we have studied the plasma removal of air contaminants such as methane, chloroform, toluene and acetone in two parallel plate packed-bed dielectric barrier discharge (DBD) reactors of different sizes. Removal and energy efficiencies have been determined as a function of the residence time of the contaminated air within the reactor, the kind of packed-bed material (ferroelectrics or classical dielectric materials), the frequency and the incorporation of a ferroelectric plate onto the active electrode together with the inter-electrode ferroelectric pellets filling the gap. Results at low frequency with the small reactor and the ferroelectric plate showed an enhancement in energy efficiency (e.g., it was multiplied by a factor of six and three for toluene and chloroform, respectively) and in removal yield (e.g., it increased from 22% to 52% for chloroform and from 15% to 21% for methane). Such enhancements have been attributed to the higher energy of plasma electrons and a lower reactor capacitance found for this plate-modified configuration. A careful analysis of reaction efficiencies and electron energy distributions for the different investigated conditions and the simulation of the electric field at the necks between ferroelectric/dielectric pellets complete the present study. Overall, the obtained results prove the critical role of the barrier architecture and operating conditions for an enhanced performance of pollution removal processes using DBD systems.


Abril, 2017 | DOI: 10.1016/j.cej.2016.11.065

Nanotecnología en Superficies y Plasma

Formation of nitrile species on Ag nanostructures supported on a-Al2O3: a new corrosion route for silver exposed to the atmosphere

Pelaez, RJ; Espinos, JP; Afonso, CN
Nanotechnology, 28 (2017) 175709

The aging of supported Ag nanostructures upon storage in ambient conditions (air and room temperature) for 20 months has been studied. The samples are produced on glass substrates by pulsed laser deposition (PLD); first a 15 nm thick buffer layer of amorphous aluminum oxide (a-Al2O3) is deposited, followed by PLD of Ag. The amount of deposited Ag ranges from that leading to a discontinuous layer up to an almost-percolated layer with a thickness of <6 nm. Some regions of the as-grown silver layers are converted, by laser induced dewetting, into round isolated nanoparticles (NPs) with diameters of up to ~25 nm. The plasmonic, structural and chemical properties of both as-grown and laser exposed regions upon aging have been followed using extinction spectroscopy, scanning electron microscopy and x-ray photoelectron spectroscopy, respectively. The results show that the discontinuous as-grown regions are optically and chemically unstable and that the metal becomes oxidized faster, the smaller the amount of Ag. The corrosion leads to the formation of nitrile species due to the reaction between NO x species from the atmosphere adsorbed at the surface of Ag, and hydrocarbons adsorbed in defects at the surface of the a-Al2O3 layer during the deposition of the Ag nanostructures by PLD that migrate to the surface of the metal with time. The nitrile formation thus results in the main oxidation mechanism and inhibits almost completely the formation of sulphate/sulphide. Finally, the optical changes upon aging offer an easy-to-use tool for following the aging process. They are dominated by an enhanced absorption in the UV side of the spectrum and a blue-shift of the surface plasmon resonance that are, respectively, related to the formation of a dielectric overlayer on the Ag nanostructure and changes in the dimensions/features of the nanostructures, both due to the oxidation process.


Abril, 2017 | DOI: 10.1088/1361-6528/aa65c0

Tribología y Protección de Superficies

Solid lubricant behavior of MoS2 and WSe2-based nanocomposite coatings

Dominguez-Meister, S; Rojas, TC; Brizuela, M; Sanchez-Lopez, JC
Science and Tecnology of Advances Materials, 18 (2017) 1

Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30-40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSe x film (specific wear rate of 2 x 10(-8) mm(3) N(-1)m(-1) and a friction coefficient of 0.03-0.05) was compared with that of the well-established MoS2 lubricant material.


Marzo, 2017 | DOI: 10.1080/14686996.2016.1275784

Materiales Nanoestructurados y Microestructura

On the effect of wall slip on the determination of the yield stress of magnetorheological fluids

Caballero-Hernandez, J; Gomez-Ramirez, A; Duran, JDG; Gonzalez-Caballero, F; Zubarev, AY; Lopez-Lopez, MT
Applied Rheology, 27 (2017) 15001 (8 pages)

We study the effect of wall slip on the measured values of the yield stress of magnetorheological (MR) fluids. For this aim we used a rheometer provided with parallel-plate geometries of two types, distinguished by having smooth or rough surfaces. We found that wall slip led to the underestimation of the yield stress when measuring geometries with smooth surfaces were used, and that this underestimation was more pronounced for the static than for the dynamic yield stress. Furthermore, we analysed the effect that both irreversible particle aggregation due to colloidal interactions and reversible magnetic fieldinduced particle aggregation had on the underestimation provoked by wall slip. We found that the higher the degree of aggregation the stronger the underestimation of the yield stress. At low intensity of the applied magnetic field irreversible particle aggregation was dominant and, thus, the underestimation of the yield stress was almost negligible for well-dispersed MR fluids, whereas it was rather pronounced for MR fluids suffering from irreversible aggregation. As the magnetic field was increased the underestimation of the yield stress became significant even for the best dispersed MR fluid.


Marzo, 2017 | DOI: 10.3933/ApplRheol-27-15001

Nanotecnología en Superficies y Plasma

Antibacterial response of titanium oxide coatings doped by nitrogen plasma immersion ion implantation

Esparza, J; Fuentes, GF; Bueno, R; Rodriguez, R; Garcia, JA; Vitas, AI; Rico, V; Gonzalez-Elipe, AR
Surface and Coatings Technology, 314 (2017) 67-71

Plasma immersion ion implantation technology has been utilized to enhance the photocatalytic activity of the anatase phase of TiO2 thin films deposited by cathodic arc evaporation PVD. The main objective of this study is to shift the light absorbance of the titania in order to obtain antibacterial activity under visible light irradiation. TiO2 thin films, deposited on polished stainless steel AISI 304 and silicon wafers, were implanted with nitrogen ions (N+/N2+) at 20 kV energy and different temperatures between 250 and 350 °C. The antibacterial activity of nitrogen implanted titania coatings has been monitored for Escherichia coli under visible light irradiation. Additionally ultra violet/visible spectrophotometry tests have been carried out to measure the changes in the light absorbance of the doped films. Further characterization has been performed, including X-ray photoelectron spectroscopy, X-ray diffraction and glow discharge optical emission spectrometry. As a result of Nitrogen implantation, the light absorption peak shifted from ultra violet region (UV-A) to visible wavelength range, which led to an increase of the antibacterial efficacy under visible light irradiation.


Marzo, 2017 | DOI: 10.1016/j.surfcoat.2016.11.002

Nanotecnología en Superficies y Plasma

Multicolored Emission and Lasing in DCM-Adamantane Plasma Nanocomposite Optical Films

Alcaire, M; Cerdan, L; Zamarro, FL; Aparicio, FJ; Gonzalez, JC; Ferrer, FJ; Borras, A; Espinos, JP; Barranco, A
ACS Applied Materials & Interfaces, 9 (2017) 8948-8959

We present a low-temperature versatile protocol for the fabrication of plasma nanocomposite thin films to act as tunable emitters and optical gain media. The films are obtained by the remote plasma-assisted deposition of a 4-(dicyano-methylene)-2-methy1-6-(4-dimethylamino-styry1)-4Hpyran (DCM) laser dye alongside adamantane. The experimental parameters that determine the concentration of the dye in the films and their optical properties, including light absorption, the refractive index, and luminescence, are evaluated. Amplified spontaneous emission experiments in the DCM/adamantane nano composite waveguides show the improvement of the copolymerized nano composites' properties compared to films that were deposited with DCM as the sole precursor. Moreover, one-dimensional distributed feed-back laser emission is demonstrated and characterized in some of the nanocomposite films that are studied. These results open new paths for the optimization of the optical and lasing properties of plasma nanocomposite polymers, which can be straightforwardly integrated as active components in optoelectronic devices.


Marzo, 2017 | DOI: 10.1021/acsami.7b01534

Tribología y Protección de Superficies - Materiales Ópticos Multifuncionales

Strong Quantum Confinement and Fast Photoemission Activation in CH3NH3PbI3 Perovskite Nanocrystals Grown within Periodically Mesostructured Films

Miguel Anaya; Andrea Rubino; Teresa Cristina Rojas; Juan Francisco Galisteo-López; Mauricio Ernesto Calvo; Hernán Míguez
Advanced Optical Materials, 5 (2017) 1601087

In this Communication, a synthetic route is demonstrated to obtain stabilized MAPbI3 nanocrystals embedded in thin metal oxide films that display well-defined and adjustable quantum confinement effects over a wide range of 0.34 eV. Mesostructured TiO2 and SiO2 films displaying an ordered 3D pore network are prepared by evaporation-induced self-assembly of a series of organic supramolecular templates in the presence of metal oxide precursors. The pores in the inorganic films obtained after thermal annealing are then used as nanoreactors to synthesize MAPbI3crystallites with narrow size distribution and average radius comprised between 1 and 4 nm, depending on the template of choice. Both the static and dynamic photoemission properties of the ensemble display features distinctive of the regime of strong quantum confinement. Photoemission maps demonstrate that the spectral and intensity properties of the luminescence extracted from the perovskite quantum dot loaded films are homogeneous over squared centimeters areas. At variance with their bulk counterparts, constant emission intensity is reached in time scales at least four orders of magnitude shorter.


Marzo, 2017 | DOI: 10.1002/adom.201601087

Nanotecnología en Superficies y Plasma

Reliability of new poly (lactic-co-glycolic acid) membranes treated with oxygen plasma plus silicon dioxide layers for pre-prosthetic guided bone regeneration processes

Castillo-Dali, G; Castillo-Oyague, R; Batista-Cruzado, A; Lopez-Santos, C; Rodriguez-Gonzalez-Elipe, A; Saffar, JL; Lynch, CD; Gutierrez-Perez, JL; Torres-Lagares, D
Medicina Oral Patología Oral y Cirugia Oral, 22 (2017) E242-E250

Background: The use of cold plasmas may improve the surface roughness of poly(lactic-co-glycolic) acid (PLGA) membranes, which may stimulate the adhesion of osteogenic mediators and cells, thus accelerating the biodegradation of the barriers. Moreover, the incorporation of metallic-oxide particles to the surface of these membranes may enhance their osteoinductive capacity. Therefore, the aim of this paper was to evaluate the reliability of a new PLGA membrane after being treated with oxygen plasma (PO2) plus silicon dioxide (SiO2) layers for guided bone regeneration (GBR) processes. 
Material and Methods: Circumferential bone defects (diameter: 11 mm; depth: 3 mm) were created on the top of eight experimentation rabbits' skulls and were randomly covered with: (1) PLGA membranes (control), or (2) PLGA/ PO2/SiO2 barriers. The animals were euthanized two months afterwards. A micromorphologic study was then performed using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone, concentration of osteoclasts, and intensity of ostheosynthetic activity were assessed and compared with those of the original bone tissue. The Kruskal-Wallis test was applied for between-group com asignificance level of a=0.05 was considered. 
Results: The PLGA/ PO2/SiO2 membranes achieved the significantly highest new bone formation, length of miner-alised bone, concentration of osteoclasts, and ostheosynthetic activity. The percentage of regenerated bone supplied by the new membranes was similar to that of the original bone tissue. Unlike what happened in the control group, PLGA/PO2/SiO2 membranes predominantly showed bone layers in advanced stages of formation. Conclusions: The addition of SiO2 layers to PLGA membranes pre-treated with PO2 improves their bone-regeneration potential. Although further research is necessary to corroborate these conclusions in humans, this could be a promising strategy to rebuild the bone architecture prior to rehabilitate edentulous areas.


Marzo, 2017 | DOI: 10.4317/medoral.21512

Nanotecnología en Superficies y Plasma

Preparation and Optimization of Fluorescent Thin Films of Rosamine-SiO2/TiO2 Composites for NO2 Sensing

Guillen, MG; Gamez, F; Suarez, B; Queiros, C; Silva, AMG; Barranco, A; Sanchez-Valencia, JR; Pedrosa, JM; Lopes-Costa, T
Materials, 10 (2017) art 124

The incorporation of a prototypical rosamine fluorescent dye from organic solutions into transparent and microstructured columnar TiO2 and SiO2 (MO2) thin films, prepared by evaporation at glancing angles (GAPVD), was evaluated. The aggregation of the adsorbed molecules, the infiltration efficiency and the adsorption kinetics were studied by means of UV-Vis absorption and fluorescence spectroscopies. Specifically, the infiltration equilibrium as well as the kinetic of adsorption of the emitting dye has been described by a Langmuir type adsorption isotherm and a pseudosecond order kinetic model, respectively. The anchoring mechanism of the rosamine to the MO2 matrix has been revealed by specular reflectance Fourier transform infrared spectroscopy and infiltration from aqueous solutions at different pH values. Finally, the sensing performance towards NO2 gas of optimized films has been assessed by following the changes of its fluorescence intensity revealing that the so-selected device exhibited improved sensing response compared to similar hybrid films reported in the literature.


Febrero, 2017 | DOI: 10.3390/ma10020124

Nanotecnología en Superficies y Plasma

Fabrication of black-gold coatings by glancing angle deposition with sputtering

Vitrey, A; Alvarez, R; Palmero, A; Gonzalez, MU; Garcia-Martin, JM
Beilstein Journal of Nanotechnology, 8 (2017) 434–439

The fabrication of black-gold coatings using sputtering is reported here. Glancing angle deposition with a rotating substrate is needed to obtain vertical nanostructures. Enhanced light absorption is obtained in the samples prepared in the ballistic regime with high tilt angles. Under these conditions the diameter distribution of the nanostructures is centered at about 60 nm and the standard deviation is large enough to obtain black-metal behavior in the visible range.


Febrero, 2017 | DOI: 10.3762/bjnano.8.46

Nanotecnología en Superficies y Plasma

Cholesterol biosensing with a polydopamine-modified nanostructured platinum electrode prepared by oblique angle physical vacuum deposition

Martin, M; Salazar, P; Alvarez, R; Palmero, A; Lopez-Santos, C; Gonzalez-Mora, JL; Gonzalez-Elipe, AR
Sensors and Actuators B-Chemical, 240 (2017) 37-45

This paper reports a novel cholesterol biosensor based on nanostructured platinum (Pt) thin films prepared by Magnetron Sputtering (MS) in an oblique angle (OAD) configuration. Pt thin films were deposited onto a gold screen-printed electrode and characterized using Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Cyclic Voltammetry (CV), X-ray Photo-electron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and wetting analysis. Our results confirmed that the film is highly porous and formed by tilted nanocolumns, with an inclination of around 40 degrees and a total thickness of 280 nm. XRD and CV analysis confirmed the polycrystalline nature of the Pt thin film. Cholesterol oxidase (ChOx) was covalently immobilized using a bioinspired polymer, polydopamine (PDA), via Schiff base formation and Michael-type addition. After being immobilized, ChOx displayed apparent activation energy of 34.09 kJ mol(-1) and Michaelis constant (K-M) values of 34.09 kJ mol(-1) and 3.65 mM, respectively, confirming the high affinity between ChOx and cholesterol and the excellent ability of the PDA film for immobilizing biological material without degradation. Under optimized working conditions the developed biosensor presented a sensitivity of 14.3 mA M(-1)cm(-2) (R-2:0.999) with a linear range up to 0.5 mM and a limit of detection of 10.5 mu M (S/N= 3). Furthermore, the biosensor exhibited a fast response (<8 s), good anti-interference properties and high stability after relatively long-term storage (2 months). 


Febrero, 2017 | DOI: 10.1016/j.snb.2016.08.092

Nanotecnología en Superficies y Plasma

High vacuum synthesis and ambient stability of bottom-up graphene nanoribbons

Fairbrother, A; Sanchez-Valencia, JR; Lauber, B; Shorubalko, I; Ruffieux, P; Hintermann, T; Fasel, R
Nanoscale, 9 (2017) 2785-2792

Carbon-based nanomaterials such as graphene are at a crucial point in application development, and their promising potential, which has been demonstrated at the laboratory scale, must be translated to an industrial setting for commercialization. Graphene nanoribbons in particular overcome one limitation of graphene in some electronic applications because they exhibit a sizeable bandgap. However, synthesis of bottom-up graphene nanoribbons is most commonly performed under ultra-high vacuum conditions, which are costly and difficult to maintain in a manufacturing environment. Additionally, little is known about the stability of graphene nanoribbons under ambient conditions or during transfer to technologically relevant substrates and subsequent device processing. This work addresses some of these challenges, first by synthesizing bottom-up graphene nanoribbons under easily obtained high vacuum conditions and identifying water and oxygen as the residual gases responsible for interfering with proper coupling during the polymerization step. And second, by using Raman spectroscopy to probe the stability of nanoribbons during storage under ambient conditions, after transfer to arbitrary substrates, and after fabrication of field-effect transistor devices, which shows structurally intact nanoribbons even several months after synthesis. These findings demonstrate the potential of graphene nanoribbon technologies by addressing some limitations which might arise in their commercialization.


Febrero, 2017 | DOI: 10.1039/C6NR08975E

Nanotecnología en Superficies y Plasma

Optical Gas Sensing of Ammonia and Amines Based on Protonated Porphyrin/TiO2 Composite Thin Films

Castillero, Pedro; Roales, Javier; Lopes-Costa, Tania; Sanchez-Valencia, Juan R.; Barranco, Angel; Gonzalez-Elipe, Agustin R.; Pedrosa, Jose M.
Sensors, 17 (2017) 24

Open porous and transparent microcolumnar structures of TiO2 prepared by physical vapour deposition in glancing angle configuration (GLAD-PVD) have been used as host matrices for two different fluorescent cationic porphyrins, 5-(N-methyl 4-pyridyl)-10,15,20-triphenyl porphine chloride (MMPyP) and meso-tetra (N-methyl 4-pyridyl) porphine tetrachloride (TMPyP). The porphyrins have been anchored by electrostatic interactions to the microcolumns by self-assembly through the dip-coating method. These porphyrin/TiO2 composites have been used as gas sensors for ammonia and amines through previous protonation of the porphyrin with HCl followed by subsequent exposure to the basic analyte. UV-vis absorption, emission, and time-resolved spectroscopies have been used to confirm the protonation-deprotonation of the two porphyrins and to follow their spectral changes in the presence of the analytes. The monocationic porphyrin has been found to be more sensible (up to 10 times) than its tetracationic counterpart. This result has been attributed to the different anchoring arrangements of the two porphyrins to the TiO2 surface and their different states of aggregation within the film. Finally, there was an observed decrease of the emission fluorescence intensity in consecutive cycles of exposure and recovery due to the formation of ammonium chloride inside the film.


Enero, 2017 | DOI: 10.3390/s17010024

Materiales para Bioingeniería y Regeneración Tisular

Regenerative Endodontic Procedures: A Perspective from Stem Cell Niche Biology

M. Marí-Beffa, J.J. Segura-Egea, A. Díaz-Cuenca
Journal of Endodontics, 43 (2017) 52-62

Introduction

Endodontics uses cell therapy strategies to treat pulpal and periapical diseases. During these therapies, surgeons aim to reconstruct the natural microenvironments that regulate the activity of dental stem cells.

Methods

We searched for more than 400 articles in PubMed using key words from regenerative endodontics and dental stem cell biology. In 268 articles, we reviewed what factors may influence histologic results after preclinical dental treatments that use regenerative endodontic procedures after pulpectomy.

Results

Several factors, such as the origin of stem cells, the biomimicry of scaffolds used, and the size of lesions, are considered to influence the histologic appearance of the regenerated pulp-dentin complex after treatments. Information is accumulating on transcription factors that generate the pulp-dentin complex and survival/trophic factors that would benefit niche recovery and histologic results.

Conclusions

In this article, we discuss the noninterchangeability of stem cells, the influence of dentin-entrapped molecule release on pulp regeneration and survival of stem cells, and the need of positional markers to assess treatments histologically. The ex vivo amplification of appropriate dental stem cells, the search for scaffolds storing the molecular diversity entrapped in the dentin, and the use of positional transcription factors as histologic markers are necessary to improve future preclinical experiments.


Enero, 2017 | DOI: 10.1016/j.joen.2016.09.011

Materiales Nanoestructurados y Microestructura

Pt-impregnated catalysts on powdery SiC and other commercial supports for the combustion of hydrogen under oxidant conditions

Arzac, G. M.; Montes, O.; Fernandez, A.
Applied Catalysis B-Envionmental, 201 (2017) 391-399

We report the study of the catalytic hydrogen combustion over Pt-impregnated powdery silicon carbide (SiC) using H2PtCl6 as precursor. The reaction was conducted in excess of oxygen. beta-SiC was selected for the study because of its thermal conductivity, mechanical properties, chemical inertness and surface area. The obtained Pt particles over SiC were medium size (average particle diameter of 5 nm for 0.5 wt% Pt). The activity of the Pt-impregnated catalyst over SiC was compared to those obtained in oxidized form over TiO2 and Al2O3 commercial supports (Pt particles very small in size, average particle diameter of 1 nm for 0.5 wt% Pt in both cases). The case of a SiO2 support was also discussed. Those Pt/SiC particles were the most active because of their higher contribution of surface Pt, indicating that partially oxidized surfaces have better activity than those totally oxidized in these conditions. SiC was modified with an acid treatment and thus bigger (average particle diameter of 7 nm for 0.5 wt% Pt) and more active Pt particles were obtained. Durability of the SiC and TiO2 supported catalysts was tested upon 5 cycles and both have shown to be durable and even more active than initially. Exposure to the oxidative reaction mixture activates the catalysts and the effect is more pronounced for the completely oxidized particles. This is due to the surface oxygen chemisorption which activates catalystsi surface.


Enero, 2017 | DOI: 10.1016/j.apcatb.2016.08.042



2016


Nanotecnología en Superficies y Plasma

Stoichiometric Control of SiOx Thin Films Grown by Reactive Magnetron Sputtering at Oblique Angles

Garcia-Valenzuela, A; Alvarez, R; Lopez-Santos, C; Ferrer, FJ; Rico, V; Guillen, E; Alcon-Camas, M; Escobar-Galindo, R; Gonzalez-Elipe, AR; Palmero, A
Plasma Processes and Polymers, 13 (2016) 1242-1248

The deposition of SiOx (x <= 2) compound thin films by the reactive magnetron sputtering technique at oblique angles is studied from both theoretical and experimental points of view. A simple mathematical formula that links the film stoichiometry and the deposition conditions is deduced. Numerous experiments have been carried out to test this formula at different deposition pressures and oblique angle geometries obtaining a fairly good agreement in all studied conditions. It is found that, at low deposition pressures, the proportion of oxygen with respect to silicon in the film increases a factor of similar to 5 when solely tilting the film substrate with respect to the target, whereas at high pressures the film stoichiometry depends very weakly on the tilt angle. This behavior is explained by considering the fundamental processes mediating the growth of the film by this technique.


Diciembre, 2016 | DOI: 10.1002/ppap.201600077

Nanotecnología en Superficies y Plasma

Non-Enzymatic Glucose Sensors Based on Nickel Nanoporous Thin Films Prepared by Physical Vapor Deposition at Oblique Angles for Beverage Industry Applications

Salazar, P; Rico, V; Gonzalez-Elipe, AR
Journal of the Electrochemical Society, 163 (14) (2016) B704-B709

Nickel nanoporous thin films deposited on Indium tin oxide conductive plates have been prepared by physical vapor deposition in an oblique angle configuration. The scanning electron microscopy characterization of these films revealed a microstructure formed by tilted nanocolumns of ca. 40-60 nm of diameter inclined by ca. 26 degrees with respect to the normal. These highly porous films had ca. 30% of void space and provided a large exposed area and outstanding diffusion properties for sensor applications. X-ray diffraction analysis confirmed the deposition of metallic nickel, while Raman and X-ray photoelectron spectroscopies demonstrated that electrochemically treated films presented an oxi/hydroxide outer layer that is the active phase for glucose sensing. The activated electrodes had a high sensitivity (2.05 A M-1 cm(-2)), an excellent coefficient of determination (R-2: 0.999), an outstanding reproducibility (3.2%) and a detection limit of 0.34 mu M. Their glucose selectivity was excellent with regard to common electroactive interferences and other sugars found in agro-alimentary products. Tests carried out with commercial beverages proved the reliability of these electrodes for glucose analysis in real conditions.


Diciembre, 2016 | DOI: 10.1149/2.1241614jes

Materiales Nanoestructurados y Microestructura

Characterization and Validation of a-Si Magnetron-Sputtered Thin Films as Solid He Targets with High Stability for Nuclear Reactions

Godinho, V; Ferrer, FJ; Fernandez, B; Caballero-Hernandez, J; Gomez-Camacho, J; Fernandez, A
ACS Omega, 1 (2016) 1229-1238

In this work, we present our magnetron sputtering based methodology to produce amorphous silicon coatings with closed porosity, as a strategy to fabricate solid helium targets, in the form of supported or self-supported thin films, for nuclear reactions. We show how by changing the He working pressure it is possible to obtain highly porous homogeneous structures incorporating different He amounts. These porous coatings (a-Si: He) are very reproducible from run to run, and the high He amount incorporated makes them excellent candidates for solid He targets. The possibility of producing self-supported films is illustrated here, and its potential use in inverse kinematics experiments with radioactive beams is shown through the dispersion in forward geometry of a stable Li-6 beam. Also the elastic scattering cross-sections for proton from helium were determined using an a-Si: He coating. The results agree well with the ones reported in the literature. These two examples validate our coatings as good candidates to be used as solid He targets in nuclear reactions. The stability of He inside the coatings, fundamental for its use as solid He targets, was investigated, both over time and after irradiation. The coatings proved to be very stable, and the amount of He inside the pores remains unaltered at least 2 years after deposition and after high irradiation fluence (5 x 10(17) particles/cm(2); with a dose rate of 5 x 10(12) particles/(cm(2) s)).


Noviembre, 2016 | DOI: 10.1021/acsomega.6b00270

Materiales Nanoestructurados y Microestructura

Tailor-made preparation of Co-C, Co-B, and Co catalytic thin films using magnetron sputtering: insights into structure-composition and activation effects for catalyzed NaBH4 hydrolysis

Paladini, M; Godinho, V; Arzac, GM; de Haro, MCJ; Beltran, AM; Fernandez, A
RSC Advances, 6 (2016) 108611-108620

The magnetron sputtering (MS) methodology is a powerful tool for tailor-made fabrication of Co-based thin film catalysts with controlled microstructures and compositions for sodium borohydride (SBH) hydrolysis. In particular, Co-C catalysts were tested in this reaction and compared to Co-B and Co catalyst coatings. The microstructural and chemical analyses by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), Rutherford back scattering (RBS) and X-ray photoelectron spectroscopy (XPS) were used to characterize a complete library of thin film catalysts. Pure Co materials were characterized by their nanocrystalline microstructure, and grain refinement was achieved via an increase in the deposition pressure. The incorporation of boron or carbon via co-deposition results in amorphization and dispersion of the active metallic Co phase. The composition can be tuned while keeping a controlled microstructure, and a comparison of activity at 25 degrees C was performed on catalysts deposited on Ni foam substrates. A comparison of the initial activities showed that the Co-B samples were more active than the Co-C samples because of electronic effects. However, a strong activation was found for the Co-C catalysts after the first use. This effect was dependent upon the incorporation of cobalt boride (CoxB) species on the catalysts' surface, as shown by XPS. After the first several uses, the activity of the Co-C samples (values up to 2495 mL min(-1) g(catalyst)(-1)) were as high as that of fresh Co-B, and the surface composition of both the catalysts was similar. This activation was not observed for the pure Co and was very weak for the Co-B catalysts. The use of polymeric (PTFE) substrates (flexible membranes) illustrated the versatility of the methodology to obtain catalytic membranes and allowed for a TEM microstructural analysis at the nanoscale. Catalytic activities at 60 degrees C were as high as 16.7 and 20 L min(-1) g(Co)(-1) for the Co-C and Co-B membranes, respectively. We determined the optimized conditions to increase the catalytic activity of Co-based coatings prepared via magnetron sputtering.


Noviembre, 2016 | DOI: 10.1039/c6ra23171c

Glutamate microbiosensors based on Prussian Blue modified carbon fiber electrodes for neuroscience applications: In-vitro characterization

Salazar, P; Martin, M; O'Neill, RD; Gonzalez-Mora, JL
Sensors and Actuators B: Chemical, 235 (2016) 117-125

Herein we report a Prussian Blue modified carbon fiber electrode (CFE/PB) to be used in microbiosensors for glutamate monitoring in physiological applications as an alternative to the classical Pt and Pt-Ir transducers. Their low dimensions (∼250 μm CFE length and ∼10 μm diameter) are advantageous for measuring in living tissues. In addition, PB-modified microelectrodes allow the detection of enzyme-generated hydrogen peroxide at a low applied potential (∼0.0 V against SCE), contrasting the high potential used in many previous designs (∼0.7 V), decreasing the endogenous interference contributions. Moreover, the electrosynthesized polymer, poly-o-phenylenediamine (PoPD), was used to improve biosensor stability and selectivity. CFE/PB was conveniently characterized using impedance, Raman and XPS spectroscopies. Optimization of the fabrication procedure and analytical conditions is described, including activation of CFE/PB, enzyme enrichment, cross-linking, stabilization and anti-interference. A range of analytical parameters were also characterized such as sensitivity, limit of detection, linear range, and enzymatic loading. Finally, an optimized biosensor displaying a linear sensitivity of 135 ± 2 nA μM−1 cm−2 (n = 3), LOD of <2 μM, linear range up to 150 μM and effectively free of interference, is proposed as a suitable candidate for in-vivo glutamate monitoring in the central nervous system.


Noviembre, 2016 | DOI: 10.1016/j.snb.2016.05.057

Nanotecnología en Superficies y Plasma

Cathode and ion-luminescence of Eu:ZnO thin films prepared by reactive magnetron sputtering and plasma decomposition of non-volatile precursors

Gil-Rostra, J; Ferrer, FJ; Martin, IR; Gonzalez-Elipe, AR; Yubero, F
Journal of Luminescence, 178 (2016) 139-146

This paper reports the luminescent behavior of Eu:ZnO thin films prepared by an one-step procedure that combines reactive magnetron sputtering deposition of ZnO with the plasma activated decomposition of a non-volatile acetylacetonate precursor of Eu sublimated in an effusion cell. Chemical composition and microstructure of the Eu:ZnO thin films have been characterized by several methods and their photo-, cathode- and ion-luminescent properties studied as a function of Eu concentration. The high transparency and well controlled optical properties of the films have demonstrated to be ideal for the development of cathode- and ion- luminescence sensors.


Octubre, 2016 | DOI: 10.1016/j.jlumin.2016.01.034

Nanotecnología en Superficies y Plasma

High-Rate Deposition of Stoichiometric Compounds by Reactive Magnetron Sputtering at Oblique Angles

Rafael Alvarez, Aurelio Garcia-Valenzuela, Carmen Lopez-Santos, Francisco J. Ferrer, Victor Rico, Elena Guillen, Mercedes Alcon-Camas, Ramon Escobar-Galindo, Agustin R. Gonzalez-Elipe, Alberto Palmero
Plasma Processes and Polymers, 13 (2016) 571-576

Target poisoning in reactive magnetron sputtering deposition of thin films is an undesired phenomenon, well known for causing a drastic fall of the process efficiency. We demonstrate that when this technique is operated at oblique angles, films with composition raging from pure metallic to stoichiometric compound can be grown in non-poisoned conditions, thus avoiding most of the associated drawbacks. We have employed amorphous TiOx, although the presented results can be easily extrapolated to other materials and conditions. It is found that the proposed method improves 400% the growth rate of TiO2 thin films.


Octubre, 2016 | DOI: 10.1002/ppap.201600019

Nanotecnología en Superficies y Plasma

Nanocolumnar association and domain formation in porous thin films grown by evaporation at oblique angles

Lopez-Santos, C; Alvarez, R; Garcia-Valenzuela, A; Rico, V; Loeffler, M; Gonzalez-Elipe, AR; Palmero, A
Nanotechnology, 27 (2016) 395702

Porous thin films grown at oblique angles by evaporation techniques are formed by tilted nanocolumnar structures which, depending on the material type and growth conditions, associate along certain preferential directions, giving rise to large domains. This arrangement, commonly denoted as bundling association, is investigated in the present work by performing fundamental experiments and growth simulations. It is proved that trapping processes of vapor species at the film surface, together with the shadowing mechanism, mediate the anisotropic widening of the nanocolumns and promote their preferential coalescence along certain directions, giving rise to domains with different shape and size. The role of these two processes is thoroughly studied in connection with the formation of these domains in materials as different as SiO2 and TiO2.


Septiembre, 2016 | DOI: 10.1088/0957-4484/27/39/395702

Nanotecnología en Superficies y Plasma

Laser Treatment of Nanoparticulated Metal Thin Films for Ceramic Tile Decoration

Rico, VJ; Lahoz, R; Rey-Garcia, F; Yubero, F; Espinos, JP; de la Fuente, GF; Gonzalez-Elipe, AR
Applied Materials & Interfaces, 8 (2016) 24880-24886

This paper presents a new method for the fabrication of metal-like decorative layers on glazed ceramic tiles. It consists of the laser treatment of Cu thin films prepared by electron-beam evaporation at glancing angles. A thin film of discontinuous Cu nanoparticles was electron-beam-evaporated in an oblique angle configuration onto ceramic tiles and an ample palette of colors obtained by laser treatment both in air and in vacuum. Scanning electron microscopy along with UV–vis–near-IR spectroscopy and time-of-flight secondary ion mass spectrometry analysis were used to characterize the differently colored layers. On the basis of these analyses, color development has been accounted for by a simple model considering surface melting phenomena and different microstructural and chemical transformations of the outmost surface layers of the samples.


Septiembre, 2016 | DOI: 10.1021/acsami.6b07469

Materiales Nanoestructurados y Microestructura

Timing of calcium nitrate addition affects morphology, dispersity and composition of bioactive glass nanoparticles

Zheng, K; Taccardi, N; Beltran, AM; Sui, BY; Zhou, T; Marthala, VRR; Hartmann, M; Boccaccini, AR
RSC Advances, 6 (2016) 95101-95111

Bioactive glass nanoparticles (BGN) are promising materials for a number of biomedical applications. Many parameters related to the synthesis of BGN using sol–gel methods can affect their characteristics. In this study, the influence of timing of calcium nitrate (calcium precursor) addition during processing on BGN characteristics was investigated. The results showed that the addition timing could affect the morphology, dispersity and composition of BGN. With delayed addition of calcium nitrate, larger, more regular and better dispersed BGN could be synthesized while the gap between nominal and actual compositions of BGN was widened. However, the addition timing had no significant influence on structural characteristics, as BGN with different addition-timing of calcium nitrate exhibited similar infrared spectra and amorphous nature. The results also suggested that monodispersed BGN could be synthesized by carefully controlling the addition of calcium nitrate. The synthesized monodispersed BGN could release Si and Ca ions continuously for up to at least 14 days. They also showed in vitro bioactivity and non-cytotoxicity towards rat bone marrow-derived mesenchymal stem cells (rBMSCs). In conclusion, the timing of calcium precursor addition is an essential parameter to be considered when producing BGN which should exhibit monodisperse characteristics for biomedical applications.


Septiembre, 2016 | DOI: 10.1039/C6RA05548F

Nanotecnología en Superficies y Plasma

Effect of Nickel and Magnesium on the Electrochemical Behavior of AA 1050 Alloys in Nitric Acid Solution

Garcia-Garcia, FJ; Skeldon, P; Thompson, GE
Journal of the Electrochemical Society, 163 (9) (2016) C593-C601

The study investigates the influence of nickel and magnesium additions to AA 1050 aluminum alloy on the electrochemical behavior of the alloy in nitric acid solution under conditions relevant to the lithographic and electronic industries. Magnesium and nickel additions are of interest, since they can improve the alloy properties for the printing process by improving reverse bending fatigue strength and thermal softening resistance, while nickel may provide uniform pitting during electrograining. Scanning electron microscopy was used to characterize the resulting surface morphologies. The addition of nickel led to an increase in the pitting and corrosion potentials; additionally, it reduced the rate of dissolution of intermetallic particles during anodic polarization and increased the rate of aluminum dissolution during cathodic polarization. In contrast, the addition of magnesium had negligible influence on the open circuit and pitting behaviors, since the magnesium is retained in solid solution and has negligible influence on the cathodic behavior of intermetallic particles, which dominate the corrosion behavior.


Septiembre, 2016 | DOI: 10.1149/2.1181609jes

Nanotecnología en Superficies y Plasma

Isotope labelling to study molecular fragmentation during the dielectric barrier discharge wet reforming of methane

Montoro-Damas, AM; Gomez-Ramirez, A; Gonzalez-Elipe, AR; Cotrino, J
Journal of Power Sources, 325 (2016) 501-505

Isotope labelling is used to study the wet plasma reforming of methane in a dielectric barrier discharge reactor using D2O and CH4 as reactants. Besides the formation of CO and hydrogen as main products, different partitions of H and D atoms are found in the hydrogen (i.e., Hz, HD, D-2), methane (i.e., CH4, CH3D and CH2D2) and water (D2O, DHO) molecules detected by mass spectrometry as outlet gases of the plasma process. The effect of operating parameters such as applied current, residence time and the addition of oxygen to the reaction mixture is correlated with the H/D distribution in these molecules, the overall reaction yield and the energetic efficiency of the process. The results prove the plasma formation of intermediate excited species that rendering water and methane instead of CO and hydrogen greatly contribute to decrease the overall energy efficiency of the reforming process.


Septiembre, 2016 | DOI: 10.1016/j.jpowsour.2016.06.028

Nanotecnología en Superficies y Plasma

Metallization of ceramic substrates by laser induced decomposition of coordination complexes

Rico, V; Lopez-Gascon, C; Espinos, JP; Lahoz, R; Laguna, M; Gonzalez-Elipe, AR; de la Fuente, GF
Journal of the European Ceramic Society, 36 (2016) 2831-2836

This work describes an in-situ Nd:YAG laser-assisted coating method to modify industrial glazed ceramic surfaces. The method makes use of a Cu polymer coordination complex, transformed via 1064 nm continuos wave (cw) laser irradiation, into a lustre-type glassy coating covering the ceramic substrate. The obtained coatings, with typical thicknesses ranging between 4 and 14 μm, become integrated onto the ceramic glaze via a sharp interface, as found by SEM observation. Diffuse Reflectance UV-vis spectroscopy shows that the lustre effect arises from surface plasmon resonant effects associated to the formation of nanometric size Cu particles dispersed throughout the glaze coating. This was confirmed by XPS analysis and other techniques showing that the laser decomposition treatment induces the redox transformation of the Cu (II) complexes, present in the original precursor, into reduced Cu (0) nanoparticles.


Septiembre, 2016 | DOI: 10.1016/j.jeurceramsoc.2016.04.016

Nanotecnología en Superficies y Plasma

Stabilization of catalyst particles against sintering on oxide supports with high oxygen ion lability exemplified by Ir-catalyzed decomposition of N2O

Yentekakis, IV; Goula, G; Panagiotopoulou, P; Kampouri, S; Taylor, MJ; Kyriakou, G; Lambert, RM
Applied Catalysis B-Environmental, 192 (2016) 357-364

Iridium nanoparticles deposited on a variety of surfaces exhibited thermal sintering characteristics that were very strongly correlated with the lability of lattice oxygen in the supporting oxide materials. Specifically, the higher the lability of oxygen ions in the support, the greater the resistance of the nanoparticles to sintering in an oxidative environment. Thus with gamma-Al2O3 as the support, rapid and extensive sintering occurred. In striking contrast, when supported on gadolinia-ceria and alumina-ceria-zirconia composite, the Ir nanoparticles underwent negligible sintering. In keeping with this trend, the behavior found with yttria-stabilized zirconia was an intermediate between the two extremes. This resistance, or lack of resistance, to sintering is considered in terms of oxygen spillover from support to nanoparticles and discussed with respect to the alternative mechanisms of Ostwald ripening versus nanoparticle diffusion. Activity towards the decomposition of N2O, a reaction that displays pronounced sensitivity to catalyst particle size (large particles more active than small particles), was used to confirm that catalytic behavior was consistent with the independently measured sintering characteristics. It was found that the nanoparticle active phase was Ir oxide, which is metallic, possibly present as a capping layer. Moreover, observed turnover frequencies indicated that catalyst-support interactions were important in the cases of the sinter-resistant systems, an effect that may itself be linked to the phenomena that gave rise to materials with a strong resistance to nanoparticle sintering. 


Septiembre, 2016 | DOI: 10.1016/j.apcatb.2016.04.011

Materiales de Diseño para la Energía y Medioambiente - Materiales Nanoestructurados y Microestructura

Monolithic supports based on biomorphic SiC for the catalytic combustion of hydrogen

Arzac, G. M.; Ramirez-Rico, J.; Gutierrez-Pardo, A.; Jimenez de Haro, M. C.; Hufschmidt, D.; Martinez-Fernandez, J.; Fernandez, A.
RSC Advances, 6 (2016) 66373-66384

Catalytic hydrogen combustion was studied with H-2/air mixtures in conditions that simulate the H-2 concentration of the exhaust gases from fuel cells (3-4% v/v H-2 in air). Pt-impregnated monoliths based on porous biomorphic SiC (bio-SiC) substrates were employed for the first time for this reaction. Capillary forces were exploited for the incipient impregnation of supports with H2PtCl6 solutions. Freeze drying permitted us to obtain a homogeneous distribution of the active phase reducing accumulation at the monolith's outer shell. The supports and catalysts were characterized from a structural and thermal point of view. Catalytic tests were performed in a homemade reactor fed with up to 1000 ml min(-1) H-2/air mixtures and a diffusional regime (non-isothermal) was achieved in the selected conditions. Catalyst loading was tested in the range of 0.25-1.5 wt% Pt and 100% conversion was achieved in all cases. Temperatures were recorded at different points of the monoliths during the reaction showing anisotropic thermal behavior for selected bio-SiC substrates. These effects are of interest for heat management applications and were explained in correlation with thermal conductivity measurements performed on the supports. Pt-impregnated monoliths were also tested in less than 100% conversion conditions (1% v/v H-2 in air) and in powder form in kinetic conditions for comparative purposes.


Septiembre, 2016 | DOI: 10.1039/c6ra09127j

Nanotecnología en Superficies y Plasma

Reduced graphene oxide-carboxymethylcellulose layered with platinum nanoparticles/PAMAM dendrimer/magnetic nanoparticles hybrids. Application to the preparation of enzyme electrochemical biosensors

Borisova, B; Sanchez, A; Jimenez-Falcao, S; Martin, M; Salazar, P; Parrado, C; Pingarron, JM; Villalonga, R
Sensors and Actuators B-Chemical, 232 (2016) 84-90

The assembly of a novel layer-by-layer biosensor architecture using hybrid nanomaterials is explored for the construction of an amperometric enzyme biosensors. The nanostructured sensing interface was prepared with poly(dopamine)-modified magnetic nanoparticles which were covalently coated with four-generation ethylenediamine core polyamidoamine G-4 dendrimers and further decorated with platinum nanoparticles. This nanohybrid was fully characterized and further layered on glassy carbon electrodes coated with a graphene oxide-carboxymethylcellulose hybrid nanomaterial through electrostatic interactions. The nanostructured surface was then employed as scaffold for the covalent immobilization of the enzyme xanthine oxidase through a glutaraldehyde-mediated cross-linking. The enzyme electrode allowed the amperometric detection of xanthine in the 50 nM-12 mu M range, with a high sensitivity of 140 mA/M cm(2) and low detection limit of 13 nM. The biosensor exhibited high reproducibility and repeatability, and was successfully tested for the quantification of xanthine in fish samples. 


Septiembre, 2016 | DOI: 10.1016/j.snb.2016.02.106

Effects of electronic and nuclear stopping power on disorder induced in GaN under swift heavy ion irradiation

Moisy, F; Sall, M; Grygiel, C; Balanzat, E; Boisserie, M; Lacroix, B; Simon, P; Monnet, I
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 381 (2016) 39-44

Wurtzite GaN epilayers, grown on the c-plane of sapphire substrate, have been irradiated with swift heavy ions at different energies and fluences, and thereafter studied by Raman scattering spectroscopy, UV–visible spectroscopy and transmission electron microscopy. Raman spectra show strong structural modifications in the GaN layer. Indeed, in addition to the broadening of the allowed modes, a large continuum and three new modes at approximately 200 cm−1, 300 cm−1 and 670 cm−1 appear after irradiation attributed to disorder-activated Raman scattering. In this case, spectra are driven by the phonon density of states of the material due to the loss of translation symmetry of the lattice induced by defects. It was shown qualitatively that both electronic excitations and elastic collisions play an important role in the disorder induced by irradiation. UV–visible spectra reveal an absorption band at 2.8 eV which is linked to the new mode at 300 cm−1observed in irradiated Raman spectra and comes from Ga-vacancies. These color centers are produced by elastic collisions (without any visible effect of electronic excitations).


Agosto, 2016 | DOI: 10.1016/j.nimb.2016.05.024

Nanotecnología en Superficies y Plasma

Effect of TiO2-Pd and TiO2-Ag on the photocatalytic oxidation of diclofenac, isoproturon and phenol

Espino-Estevez, MR; Fernandez-Rodriguez, C; Gonzalez-Diaz, OM; Arana, J; Espinos, JP; Ortega-Mendez, JA; Dona-Rodriguez, JM
Chemical Engineering Journal, 298 (2016) 82-95

The effects of silver and palladium metals on the photocatalytic degradation of diclofenac sodium salt (DCF), isoproturon (IP) and phenol (PHL) in water over lab-made TiO2 synthesized following a sol-gel method were investigated. Silver and palladium catalysts were prepared by photodeposition at 1 wt.% of loading metal. The resulting materials were characterized through BET, XRD, TEM, SEM, XPS and DRS-UV-Vis. The photodeposition test conditions of both metals determined their final oxidation state, with reduced particles of palladium and silver as well as silver oxides found on the catalysts. The results showed that the type of metal had different effects on the photodegradation mechanism depending on the nature of the pollutants. Accordingly, the highest degradation rate for IP and DCF was obtained when using the catalyst photodeposited with palladium and for PHL the catalyst photodeposited with silver. The photodegradation intermediates of PHL, DCF and IP were also identified.


Agosto, 2016 | DOI: 10.1016/j.cej.2016.04.016

Nanotecnología en Superficies y Plasma

Synthesis, characterization and performance of robust poison resistant ultrathin film yttria stabilized zirconia nickel anodes for application in solid electrolyte fuel cells

Garcia-Garcia, FJ; Yubero, F; Espinos, JP; Gonzalez-Elipe, AR; Lambert, RM
Journal of Power Sources, 324 (2016) 679-686

We report on the synthesis of undoped ∼5 μm YSZ-Ni porous thin films prepared by reactive pulsed DC magnetron sputtering at an oblique angle of incidence. Pre-calcination of the amorphous unmodified precursor layers followed by reduction produces a film consisting of uniformly distributed tilted columnar aggregates having extensive three-phase boundaries and favorable gas diffusion characteristics. Similarly prepared films doped with 1.2 at.% Au are also porous and contain highly dispersed gold present as Ni-Au alloy particles whose surfaces are strongly enriched with Au. With hydrogen as fuel, the performance of the undoped thin film anodes is comparable to that of 10–20 times thicker typical commercial anodes. With a 1:1 steam/carbon feed, the un-doped anode cell current rapidly falls to zero after 60 h. In striking contrast, the initial performance of the Au-doped anode is much higher and remains unaffected after 170 h. Under deliberately harsh conditions the performance of the Au-doped anodes decreases progressively, almost certainly due to carbon deposition. Even so, the cell maintains some activity after 3 days operation in dramatic contrast with the un-doped anode, which stops working after only three hours of use. The implications and possible practical application of these findings are discussed.


Julio, 2016 | DOI: 10.1016/j.jpowsour.2016.05.124

Materiales para Bioingeniería y Regeneración Tisular

In vitro stimulation of MC3T3-E1cells and sustained drug delivery by a hierarchical nanostructured SiO2-CaO-P2O5 scaffold

Ramiro-Gutierrez, ML; Santos-Ruiz, L; Borrego-Gonzalez, S; Becerra, J; Diaz-Cuenca, A
Microporous and Mesoporous Materials, 229 (2016) 31-43

A hierarchical scaffold, SP1_h_HA, consisting of a biomimetic nano-hydroxyapatite surface coating growth onto a reticulated structure having a nano-organized porous texture was fabricated and functionally studied in vitro using osteoprogenitor cells. Three scaffold materials (designated as SP0_l, SP0_h and SP1_h) were also prepared through modifications of the processing variables as control materials. The scaffolds were characterized showing well-interconnected micron-sized voids and a nano (4–6 nm)-organized porosity. In order to evaluate potential local risks and performance over mammalian cells the scaffolds were studied in comparison with a commercial clinical grade scaffold material, ProOsteon® 500R. MC3T3-E1 pre-osteoblast viability was evaluated using the resazurin assay and field emission gun scanning electron microscopy (FEG-SEM), showing in all cases good proliferative response. Alkaline phosphatase (ALP) production and analysis of the differentiation marker osteocalcin (OC), both in non-osteoinductive and osteoinductive media, were assessed using colorimetric and RT-PCR methods. The implementation of the new scaffold processing variables enhanced ALP activity with respect to the SP0_l control material. The cell proliferation, ALP activity, and mRNA OC expression response to SP1_h_HA scaffold were higher than those observed after the use of ProOsteon® 500R. In addition, SP1_h_HA scaffold showed a two stage sustained release of gentamicin sulfate (GS) instead of the quick release shown by ProOsteon® 500R. These results suggest that our synthesized scaffold could be effective for antibiotic delivery and bone regeneration and a better option than ProOsteon® 500R.


Julio, 2016 | DOI: 10.1016/j.micromeso.2016.04.018

Nanotecnología en Superficies y Plasma

A Full Vacuum Approach for the Fabrication of Hybrid White-Light-Emitting Thin Films and Wide-Range In Situ Tunable Luminescent Microcavities

Y. Oulad-Zian, J.R. Sánchez-Valencia, M. Oliva, J. Parra-Barranco, M. Alcaire, F.J. Aparicio, A. Mora-Boza, J.P. Espinós, F. Yubero, A.R. González-Elipe, A. Barranco, A. Borras
Advanced Optical Materials, 4 (2016) 1134

A wide-range in situ tunable 1D Bragg microcavity including a hybrid layer as white light emitter defect is shown by J. R. Sanchez-Valencia, A. Borras, and co-workers on page 1124. White emission is obtained by Förster resonance energy transfer between blue (1,3,5-triphenyl-2-pyrazoline) and orange (rubrene) dyes homogeneously infiltrated within the host nanocolumnar SiO2film, which is formed by glancing angle deposition. Sequential physical vapor deposition at low temperatures provides the organic dyes localization within the porous nanostructure of the defect layer.


Junio, 2016 | DOI: 10.1002/adom.201670041

Nanotecnología en Superficies y Plasma

The 16th European Conference on Applications of Surface and Interface Analysis

Yubero, F
Surface and Interface Analysis

Nanotecnología en Superficies y Plasma

Portable IR dye laser optofluidic microresonator as a temperature and chemical sensor

Lahoz, F; Martin, IR; Gil-Rostra, J; Oliva-Ramirez, M; Yubero, F; Gonzalez-Elipe, AR
Optics Express, 24 (2016) 14383-14392

A compact and portable optofluidic microresonator has been fabricated and characterized. It is based on a Fabry-Perot microcavity consisting essentially of two tailored dichroic Bragg mirrors prepared by reactive magnetron sputtering deposition. The microresonator has been filled with an ethanol solution of Nile-Blue dye. Infrared laser emission has been measured with a pump threshold as low as 0.12 MW/cm2 and an external energy conversion efficiency of 41%. The application of the device as a temperature and a chemical sensor is demonstrated. Small temperature variations as well as small amount of water concentrations in the liquid laser medium are detected as a shift of the resonant laser modes.


Junio, 2016 | DOI: 10.1364/OE.24.014383

Nanotecnología en Superficies y Plasma

Dye-based photonic sensing systems

Aparicio, FJ; Alcaire, M; Gonzalez-Elipe, AR; Barranco, A; Holgado, M; Casquel, R; Sanza, FJ; Griol, A; Bernier, D; Dortu, F; Caceres, S; Antelius, M; Lapisa, M; Sohlstrom, H; Niklaus, F
Sensors and Actuators B: Chemical, 228 (2016) 649-657

We report on dye-based photonic sensing systems which are fabricated and packaged at wafer scale. For the first time luminescent organic nanocomposite thin-films deposited by plasma technology are integrated in photonic sensing systems as active sensing elements. The realized dye-based photonic sensors include an environmental NO2 sensor and a sunlight ultraviolet light (UV) A+B sensor. The luminescent signal from the nanocomposite thin-films responds to changes in the environment and is selectively filtered by a photonic structure consisting of a Fabry-Perot cavity. The sensors are fabricated and packaged at wafer-scale, which makes the technology viable for volume manufacturing. Prototype photonic sensor systems have been tested in real-world scenarios. 


Junio, 2016 | DOI: 10.1016/j.snb.2016.01.092

Nanotecnología en Superficies y Plasma

The interaction between hybrid organic-inorganic halide perovskite and selective contacts in perovskite solar cells: an infrared spectroscopy study

Idigoras, J; Todinova, A; Sanchez-Valencia, JR; Barranco, A; Borras, A; Anta, JA
Physical Chemistry Chemical Physics, 18 (2016) 13583-13590

The interaction of hybrid organic-inorganic halide perovskite and selective contacts is crucial to get efficient, stable and hysteresis-free perovskite-based solar cells. In this report, we analyze the vibrational properties of methylammonium lead halide perovskites deposited on different substrates by infrared absorption (IR) measurements (4000-500 cm(-1)). The materials employed as substrates are not only characterized by different chemical natures (TiO2, ZnO and Al2O3), but also by different morphologies. For all of them, we have investigated the influence of these substrate properties on perovskite formation and its degradation by humidity. The effect of selective-hole contact (Spiro-OmeTad and P3HT) layers on the degradation rate by moisture has also been studied. Our IR results reveal the existence of a strong interaction between perovskite and all ZnO materials considered, evidenced by a shift of the peaks related to the N-H vibrational modes. The interaction even induces a morphological change in ZnO nanoparticles after perovskite deposition, pointing to an acid-base reaction that takes place through the NH3+ groups of the methylammonium cation. Our IR and X-ray diffraction results also indicate that this specific interaction favors perovskite decomposition and PbI2 formation for ZnO/perovskite films subjected to humid conditions. Although no interaction is observed for TiO2, Al2O3, and the hole selective contact, the morphology and chemical nature of both contacts appear to play an important role in the rate of degradation upon exposure to moisture.


Mayo, 2016 | DOI: 10.1039/c6cp01265e

Nanotecnología en Superficies y Plasma

Non-enzymatic Glucose electrochemical sensor made of porous NiO thin films prepared by reactive magnetron sputtering at oblique angles

Garcia-Garcia, FJ; Salazar, P; Yubero, F; Gonzalez-Elipe, AR
Electrochimica Acta, 201 (2016) 38-44

Porous nanostructured NiO thin films have been prepared in one step by magnetron sputtering in an oblique angle configuration (MS-OAD) and used as electrodes for the non-enzymatic detection of glucose. The films have been thoroughly characterized by different complementary techniques and their performance for the analysis of glucose in basic solutions determined by electrochemical methods. These electrodes presented four times higher sensitivity that equivalent compact thin films prepared by MS in a normal configuration and were superior in terms of sensitivity than majority of nickel based electrodes prepared by other methods. Finally, a high sensitivity towards detection of glucose in blood, insensitivity to common interferences, a long term stability and high reproducibility confirmed the good performance and reliability of these electrodes for practical analytical purposes.


Mayo, 2016 | DOI: 10.1016/j.electacta.2016.03.193

Tribología y Protección de Superficies

Structure, electrochemical properties and functionalization of amorphous CN films deposited by femtosecond pulsed laser ablation

Maddi, C; Bourquard, F; Tite, T; Loir, AS; Donnet, C; Garrelie, F; Barnier, V; Wolski, K; Fortgang, P; Zehani, N; Braiek, M; Lagarde, F; Chaix, C; Jaffrezic-Renault, N; Rojas, TC; Sanchez-Lopez, JC
Diamond and Related Materials,65 (2016) 17-25

Amorphous carbon nitride (a-C:N) material has attracted much attention in research and development Recently, it has become a more promising electrode material than conventional carbon based electrodes in electrochemical and biosensor applications. Nitrogen containing amorphous carbon (a-C:N) thin films have been synthesized by femtosecond pulsed laser deposition (fs-PLD) coupled with plasma assistance through Direct Current (DC) bias power supply. During the deposition process, various nitrogen pressures (0 to 10 Pa) and DC bias (0 to -350 V) were used in order to explore a wide range of nitrogen content into the films. The structure and chemical composition of the films have been studied by using Raman spectroscopy, electron energy-loss spectroscopy (EELS) and high-resolution transmission electron microscopy (HRTEM). Increasing the nitrogen pressure or adding a DC bias induced an increase of the N content, up to 21 at%. Nitrogen content increase induces a higher sp(2) character of the film. However DC bias has been found to increase the film structural disorder, which was detrimental to the electrochemical properties. Indeed the electrochemical measurements, investigated by cyclic voltammetry (CV), demonstrated that a-C:N film with moderate nitrogen content (10 at.%) exhibited the best behavior, in terms of reversibility and electron transfer kinetics. Electrochemical grafting from diazonium salts was successfully achieved on this film, with a surface coverage of covalently bonded molecules close to the dense packed monolayer of ferrocene molecules. Such a film may be a promising electrode material in electrochemical detection of electroactive pollutants on bare film, and of biopathogen molecules after surface grafting of the specific affinity receptor. 


Abril, 2016 | DOI: 10.1016/j.diamond.2016.01.001

Nanotecnología en Superficies y Plasma

Nickel-copper bilayer nanoporous electrode prepared by physical vapor deposition at oblique angles for the non-enzymatic determination of glucose

Salazar, P; Rico, V; Gonzalez-Elipe, AR
Sensors and Actuators B: Chemical, 226 (2016) 436-443

This work presents a novel bilayer Ni/Cu porous nanostructured film electrode prepared by physical vapor deposition (PVD) in an oblique angle configuration. Scanning electron microscopy (SEM) data revealed that the film, with an approximate thickness of 200 nm, is formed by tilted nanocolumns of around 50 nm of diameter and an inclination of 30° with respect to the surface normal. X ray photoelectron spectroscopy (XPS) data confirmed a bilayer configuration with Cu and Ni located at the top and bottom parts of the film, respectively. A porosity of ca. 45–35% as determined by Rutherford back scattering (RBS) offered a large exposed area and excellent diffusion properties that, combined with a very good catalytic activity, rendered these films excellent electrodes for the quantitative determination of glucose. Under optimized working conditions of detection these electrodes presented a high sensitivity of 2.53 A M−1 cm−2 (R2: 0.999), a limit of detection of 0.23 μM and a time response of ca. 2 s. The sensors did not show any loss of response during a period of 4 months. The selectivity of the sensor was checked against various interferences, including physiological compounds, different sugars and ethanol, in all cases with excellent results. The feasibility of using of this sensor for practical applications was confirmed by successfully determining the glucose content in different commercial beverages.


Abril, 2016 | DOI: 10.1016/j.snb.2015.12.003

Nanotecnología en Superficies y Plasma

Light management: porous 1-dimensional nanocolumnar structures as effective photonic crystals for perovskite solar cells

Ramos, FJ; Oliva-Ramirez, M; Nazeeruddin, MK; Graetzel, M; Gonzalez-Elipe, AR; Ahmad, S
Journal of Materials Chemistry A, 4 (2016) 4962-4970

Hybrid organic-inorganic perovskite solar cells are a topic of increasing interest, as in a short time span they are able to lead in the third generation photovoltaics. Organohalide perovskites possess exceptional optoelectronic and physical properties, thus making their implementation possible in many diverse configurations of photovoltaic devices. In this work, we present three different configurations of porous 1-dimensional photonic crystals (1-DPCs) based on alternated nanocolumnar layers of oxides with different refractive indices (n) that were deposited by Physical Vapor Deposition at Oblique Angle Deposition (PVD-OAD). They are then implemented as the photoanode in CH3NH3PbI3 solar cells to improve the management of light into the device. These configurations improved the performance of the photovoltaic system by designing a light interference structure capable of enhancing the absorption capability of the perovskite. A device fabricated using these photonic crystal structures presented an efficiency >12% in contrast with only 10.22% for a reference device based on non-photonic crystal TiO2 layers deposited under analogous conditions.


Abril, 2016 | DOI: 10.1039/c5ta08743k

Nanotecnología en Superficies y Plasma

Growth Assisted by Glancing Angle Deposition: A New Technique to Fabricate Highly Porous Anisotropic Thin Films

Sanchez-Valencia, JR; Longtin, R; Rossell, MD; Groning, P
ACS Applied Materials & Interfaces, 8 (2016) 8686-8693

We report a new methodology based on glancing angle deposition (GLAD) of an organic molecule in combination with perpendicular growth of a second inorganic material. The resulting thin films retain a very well-defined tilted columnar microstructure characteristic of GLAD with the inorganic material embedded inside the columns. We refer to this new methodology as growth assisted by glancing angle deposition or GAGLAD, since the material of interest (here, the inorganic) grows in the form of tilted columns, though it is deposited under a nonglancing configuration. As a “proof of concept”, we have used silver and zinc oxide as the perpendicularly deposited material since they usually form ill-defined columnar microstructures at room temperature by GLAD. By means of our GAGLAD methodology, the typical tilted columnar microstructure can be developed for materials that otherwise do not form ordered structures under conventional GLAD. This simple methodology broadens significantly the range of materials where control of the microstructure can be achieved by tuning the geometrical deposition parameters. The two examples presented here, Ag/Alq3 and ZnO/Alq3, have been deposited by physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD), respectively: two different vacuum techniques that illustrate the generality of the proposed technique. The two type of hybrid samples present very interesting properties that demonstrate the potentiality of GAGLAD. On one hand, the Ag/Alq3 samples present highly optical anisotropic properties when they are analyzed with linearly polarized light. To our knowledge, these Ag/Alq3 samples present the highest angular selectivity reported in the visible range. On the other hand, ZnO/Alq3 samples are used to develop highly porous ZnO thin films by using Alq3 as sacrificial material. In this way, antireflective ZnO samples with very low refractive index and extinction coefficient have been obtained.


Abril, 2016 | DOI: 10.1021/acsami.6b00232

Nanotecnología en Superficies y Plasma

Pre-prosthetic use of poly(lactic-co-glycolic acid) membranes treated with oxygen plasma and TiO2 nanocomposite particles for guided bone regeneration processes

Castillo-Dali, G; Castillo-Oyague, R; Terriza, A; Saffar, JL; Batista-Cruzado, A; Lynch, CD; Sloan, AJ; Gutierrez-Perez, JL; Torres-Lagares, D
Journal of Dentistry, 47 (2016) 71-79

Objectives: Guided bone regeneration (GBR) processes are frequently necessary to achieve appropriate substrates before the restoration of edentulous areas. This study aimed to evaluate the bone regeneration reliability of a new poly-lactic-co-glycolic acid (PLGA) membrane after treatment with oxygen plasma (PO2) and titanium dioxide (TiO2) composite nanoparticles. 

Methods: Circumferential bone defects (diameter: 10 mm; depth: 3 mm) were created on the parietal bones of eight experimentation rabbits and were randomly covered with control membranes (Group 1: PLGA) or experimental membranes (Group 2: PLGA/PO2/TiO2). The animals were euthanized two months afterwards, and a morphologic study was then performed under microscope using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone formed in the grown defects, concentration of osteoclasts, and intensity of osteosynthetic activity were assessed. Comparisons among the groups and with the original bone tissue were made using the Kruskal-Wallis test. The level of significance was set in advance at a = 0.05. 

Results: The experimental group recorded higher values for new bone formation, mineralised bone length, and osteoclast concentration; this group also registered the highest osteosynthetic activity. Bone layers in advanced formation stages and low proportions of immature tissue were observed in the study group. 


Abril, 2016 | DOI: 10.1016/j.jdent.2016.01.015

Nanotecnología en Superficies y Plasma

Electrocatalytic System for the Simultaneous Hydrogen Production and Storage from Methanol

Gonzalez-Cobos, J; Rico, VJ; Gonzalez-Elipe, AR; Valverde, JL; de Lucas-Consuegra, A
ACS Catalysis, 6 (2016) 1942-1951

This paper reports a groundbreaking approach for simultaneous hydrogen production and storage that entails catalysis, electrochemistry, surface science, and materials synthesis. A novel electrocatalytic system is developed based on nickel nanocolumnar films of controlled microstructure prepared on K-βAl2O3 solid electrolyte supports by oblique angle physical vapor deposition. The outstanding characteristics of this system are a hydrogen storage capacity of up to 19 g of H2 (100 g of Ni)−1, which is unparalleled in the literature and the possibility of controlling its release electrochemically, under fixed mild conditions (280 °C and normal pressure). H2 is produced in situ by methanol steam re-forming on the Ni catalyst, and it spills over onto graphene oxide aggregates formed during the catalytic process, as confirmed by SEM, FTIR, and Raman spectroscopy. The proposed storage mechanism considers a synergetic contribution of both Ni and graphene oxide, promoted by K+ ions, in enhancing the hydrogen storage capacity of the system.


Marzo, 2016 | DOI: 10.1021/acscatal.5b02844

Nanotecnología en Superficies y Plasma

Characterization and application of a new pH sensor based on magnetron sputtered porous WO3 thin films deposited at oblique angles

Salazar, P; Garcia-Garcia, FJ; Yubero, F; Gil-Rostra, J; Gonzalez-Elipe, AR
Electrochimica Acta, 193 (2016) 24-31

In this communication we report about an outstanding solid-state pH sensor based on amorphous nanocolumnar porous thin film electrodes. Transparent WO3 thin films were deposited by reactive magnetron sputtering in an oblique angle configuration to enhance their porosity onto indium tin oxide (ITO) and screen printed electrodes (SPE). The potentiometric pH response of the nanoporous WO3-modified ITO electrode revealed a quasi-Nernstian behaviour, i.e. a linear working range from pH 1 to 12 with a slope of about -57.7 mV/pH. pH detection with this electrode was quite reproducible, displayed excellent anti-interference properties and a high stable response that remained unaltered over at least 3 months. Finally, a pH sensor was developed using nanoporous WO3-modified screen printed electrode (SPE) using a polypyrrole-modified Ag/AgCl electrode as internal reference electrode. This full solid state pH sensor presented a Nernstian behaviour with a slope of about -59 mV/pH and offered important analytical and operation advantages for decentralized pH measurements in different applications. 


Marzo, 2016 | DOI: 10.1016/j.electacta.2016.02.040

Nanotecnología en Superficies y Plasma

Perspectives on oblique angle deposition of thin films: From fundamentals to devices

Barranco, A; Borras, A; Gonzalez-Elipe, AR; Palmero, A
Progress in Materials Science, 78 (2016) 59-153

The oblique angle configuration has emerged as an invaluable tool for the deposition of nanostructured thin films. This review develops an up to date description of its principles, including the atomistic mechanisms governing film growth and nanostructuration possibilities, as well as a comprehensive description of the applications benefiting from its incorporation in actual devices. In contrast with other reviews on the subject, the electron beam assisted evaporation technique is analyzed along with other methods operating at oblique angles, including, among others, magnetron sputtering and pulsed laser or ion beam-assisted deposition techniques. To account for the existing differences between deposition in vacuum or in the presence of a plasma, mechanistic simulations are critically revised, discussing well-established paradigms such as the tangent or cosine rules, and proposing new models that explain the growth of tilted porous nanostructures. In the second part, we present an extensive description of applications wherein oblique-angle-deposited thin films are of relevance. From there, we proceed by considering the requirements of a large number of functional devices in which these films are currently being utilized (e.g., solar cells, Li batteries, electrochromic glasses, biomaterials, sensors, etc.), and subsequently describe how and why these nanostructured materials meet with these needs. 


Marzo, 2016 | DOI: 10.1016/j.pmatsci.2015.06.003

Materiales Nanoestructurados y Microestructura

Nitrogen Nanobubbles in a-SiOxNy Coatings: Evaluation of Its Physical Properties and Chemical Bonding State by Spatially Resolved Electron Energy-Loss Spectroscopy

Lacroix, B.; Godinho, V.; Fernández, A.
Journal of Physical Chemistry C, 120 (2016) 5651-5658

Nanoporous silicon-based materials with closed porosity filled with the sputtering gas have been recently developed by magnetron sputtering. In this work the physical properties (density and pressure) of molecular nitrogen inside closed pores in a SiOxNy coating are investigated for the first time using spatially resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope. The paper offers a detailed methodology to record and process multiple EELS spectrum images (SIs) acquired at different energy ranges and with different dwell times. An adequate extraction and quantification of the N–K edge contribution due to the molecular nitrogen inside nanopores is demonstrated. Core-loss intensity and N chemical bond state were evaluated to retrieve 2D maps revealing the stable high density of molecular nitrogen (from 40 to 70 at./nm3) in nanopores of different size (20–11 nm). This work provides new insights into the quantification of molecular N2 trapped in porous nitride matrices that could also be applied to other systems.


Marzo, 2016 | DOI: 10.1021/acs.jpcc.5b09036

Nanotecnología en Superficies y Plasma

Nanoindentation and scratch resistance of multilayered TiO2-SiO2 coatings with different nanocolumnar structures deposited by PV-OAD

Roa, JJ; Rico, V; Oliva-Ramirez, M; Gonzalez-Elipe, AR; Jimenez-Pique, E
Journal of Physics D-Applied Physics, 49 (2016) 13

This paper presents a study of the mechanical properties and an evaluation of damage mechanisms of nanocolumnar TiO2-SiO2 multilayer coatings prepared by physical vapour oblique angle deposition at different configurations (slanted, zigzag or chiral) and two zenithal evaporation angles (70 degrees or 85 degrees). The characterization at micro-and nanometric length scales of the mechanical properties of the multilayers has been carried out by nanoindentation and nanoscratch tests, while the morphological evaluation of the surface and sub-surface damages produced with a sharp indenter and the adhesive and/or cohesive failures between coating and substrate have been investigated by field emission scanning electron microscopy and focused ion beam, respectively. The obtained results have shown that the main processing parameters controlling the mechanical response of the different multilayers is the zenithal angle of deposition and the number of layers in the multilayer stack, while the coating architecture had only a minor effect on the mechanical response. This analysis also revealed a higher resistance to scratch testing and a brittle failure behaviour for the low zenithal angle coatings as compared with the high angle ones.


Febrero, 2016 | DOI: 10.1088/0022-3727/49/13/135104

Materiales Nanoestructurados y Microestructura

Determination of the Anisotropic Elastic Properties of Rocksalt Ge2Sb2Te5 by XRD, Residual Stress, and DFT

Cecchini, R; Kohary, K; Fernandez, A; Cabibbo, M; Marmier, A
Journal of Physical Chemistry C, 120 (2016) 5624-5629

The chalcogenide material Ge2Sb2Te5 is the prototype phase-change material, with widespread applications for optical media and random access memory. However, the full set of its independent elastic properties has not yet been published. In this study, we determine the elastic constants of the rocksalt Ge2Sb2Te5, experimentally by X-ray diffraction (XRD) and residual stress and computationally by density functional theory (DFT). The stiffnesses (XRD-stress/DFT) in GPa are C-11 = 41/58, C-12 = 7/8, and C-44 = 8/12, and the Zener ratio is 0.46/0.48. These values are important to understand the effect of elastic distortions and nonmelting processes on the performances of increasingly small phase change data bits.


Febrero, 2016 | DOI: 10.1021/acs.jpcc.5b09867

Nanotecnología en Superficies y Plasma

Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls

Filippin, AN; Macias-Montero, M; Saghi, Z; Idigoras, J; Burdet, P; Barranco, A; Midgley, P; Anta, JA; Borras, A
Scientific Reports, 5 (2016) 20637

A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a post-annealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensor.


Febrero, 2016 | DOI: 10.1038/srep20637

Nanotecnología en Superficies y Plasma

Ripening and recrystallization of NaCl nanocrystals in humid conditions

Oliva-Ramirez, M; Macias-Montero, M; Borras, A; Gonzalez-Elipe, AR
RSC Advances, 6 (2016) 3778-3782

This study shows that Ostwald ripening, a universal mechanism responsible for the increase of crystal size during precipitation from solutions, can be meditated by ion diffusion through condensed monolayers of water that connect separated nanocrystals. In an environmental electron microscope we have observed "in situ" the time evolution of the number, shape, size and crystallographic texture of NaCl nanoparticles deposited by electron beam evaporation at oblique angles. Analysis of NaCl nanoparticles before and after water vapor condensation has evidenced that the size of nanocrystals is not the unique driving force inducing nanoparticle ripening and recrystallization, but the faceting of their crystalline habits and the amorphisation degree of the initially deposited nuclei also play important roles. These findings have implications for other crystallization and nucleation processes and can be of relevance for rock weathering and related phenomena.


Febrero, 2016 | DOI: 10.1039/C5RA22425J

Nanotecnología en Superficies y Plasma

Nanostructured Ti thin films by magnetron sputtering at oblique angles

Alvarez, R; Garcia-Martin, JM; Garcia-Valenzuela, A; Macias-Montero, M; Ferrer, FJ; Santiso, J; Rico, V; Cotrino, J; Gonzalez-Elipe, AR; Palmero, A
Journal of Physics D-Applied Physics, 49 (2016) 045303

The growth of Ti thin films by the magnetron sputtering technique at oblique angles and at room temperature is analysed from both experimental and theoretical points of view. Unlike other materials deposited in similar conditions, the nanostructure development of the Ti layers exhibits an anomalous behaviour when varying both the angle of incidence of the deposition flux and the deposition pressure. At low pressures, a sharp transition from compact to isolated, vertically aligned, nanocolumns is obtained when the angle of incidence surpasses a critical threshold. Remarkably, this transition also occurs when solely increasing the deposition pressure under certain conditions. By the characterization of the Ti layers, the realization of fundamental experiments and the use of a simple growth model, we demonstrate that surface mobilization processes associated to a highly directed momentum distribution and the relatively high kinetic energy of sputtered atoms are responsible for this behaviour.


Febrero, 2016 | DOI: 10.1088/0022-3727/49/4/045303

Nanotecnología en Superficies y Plasma

Quantitative analysis of Ni 2p photoemission in NiO and Ni diluted in a SiO2 matrix

Pauly, N; Yubero, F; Garcia-Garcia, FJ; Tougaard, S
Surface Science, 644 (2016) 46-52

In X-ray excited photoelectron emission (XPS), besides the initial excitation process, the shape and intensity of photoelectron peaks are strongly affected by extrinsic excitations due to electron transport out of the surface (including bulk and surface effects) and to intrinsic excitations due to the sudden creation of the static core hole. To make an accurate quantitative interpretation of features observed in XPS, these effects must be included in the theoretical description of the emitted photoelectron spectra. It was previously shown [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17] that these three effects can be calculated by means of the QUEELS-XPS software (Quantitative analysis of Electron Energy Losses at Surfaces for XPS) in terms of effective energy-differential inelastic electron scattering cross-sections. The only input needed to calculate these cross-sections is the energy loss function of the media which is determined from analysis of Reflection Electron Energy Loss Spectra (REELS). The full XPS spectrum is then modeled by convoluting this energy loss cross-section with the primary excitation spectrum that accounts for all effects which are part of the initial photo-excitation process, i.e. lifetime broadening, spin-orbit coupling, and multiplet splitting. In this paper we apply the previously presented procedure to the study of Ni 2p photoemission in NiO and Ni diluted in a SiO2 matrix (Ni:SiO2), samples being prepared by reactive magnetron sputtering at room temperature. We observe a significant difference between the corresponding Ni 2p primary excitation spectra. The procedure allows quantifying the relative intensity of the c3d(9)L, c3d(10)L(2), and c3d(8) final states contributing to the Ni 2p photoemission spectra of the Ni2+ species in the oxide matrices. Especially, the intensity ratio in NiO between the non-local and local contributions to the 3d(9)L configuration is determined to be 2.5. Moreover the relative intensity ratio of the c3d(9)L/c3d(10)L(2)/c3d(8) configurations is found to be 1.0/0.83/0.11 for both the NiO and Ni:SiO2 samples. 


Enero, 2016 | DOI: 10.1016/j.susc.2015.09.012

Nanotecnología en Superficies y Plasma

Optofluidic Modulation of Self-Associated Nanostructural Units Forming Planar Bragg Microcavities

Oliva-Ramirez, M; Barranco, A; Loffler, M; Yubero, F; Gonzalez-Elipe, AR
ACS Nano, 10 (2016) 1256-1264

Bragg microcavities (BMs) formed by the successive stacking of nanocolumnar porous SiO2 and TiO2 layers with slanted, zigzag, chiral, and vertical configurations are prepared by physical vapor deposition at oblique angles while azimuthally varying the substrate orientation during the multilayer growth. The slanted and zigzag BMs act as wavelength-selective optical retarders when they are illuminated with linearly polarized light, while no polarization dependence is observed for the chiral and vertical cavities. This distinct optical behavior is attributed to a self-nanostructuration mechanism involving a fence-bundling association of nanocolumns as observed by focused ion beam scanning electron microscopy in the slanted and zigzag microcavities. The outstanding retarder response of the optically active BMs can be effectively modulated by dynamic infiltration of nano- and mesopores with liquids of different refraction indices acting as a switch of the polarization behavior. The unprecedented polarization and tunable optofluidic properties of these nanostructured photonic systems have been successfully simulated with a simple model that assumes a certain birefringence for the individual stacked layers and accounts for the light interference phenomena developed in the BMs. The possibilities of this type of self-arranged nanostructured and optically active BMs for liquid sensing and monitoring applications are discussed.


Enero, 2016 | DOI: 10.1021/acsnano.5b06625

Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies

Highly Porous ZnO Thin Films and 1D Nanostructures by Remote Plasma Processing of Zn-Phthalocyanine

Alcaire, M; Filippin, AN; Macias-Montero, M; Sanchez-Valencia, JR; Rojas, TC; Mora-Boza, A; Lopez-Santos, C; Espinos, JP; Barranco, A; Borras, A
Plasma Processes and Polymers, 13 (2016) 287-297

In this paper the fabrication of highly porous 1D nanostructures by a vacuum and plasma etching combined protocol is presented. Zn-phthalocyanine (ZnPc) is utilized as a solid precursor to form the ZnO. First the ZnPc is sublimated in low argon pressure. Depending on the substrate temperature and microstructure, polycrystalline films or single crystal ZnPc nanowires are grown. These starting materials are then subjected to a remote plasma oxidizing treatment. Experimental parameters such as substrate position, plasma power, treatment duration, and substrate temperature determine the microstructure and properties of the final ZnO nanostructures. The article gathers an in depth study of the obtained porous nanostructured films following scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), UV-Vis transmittance, and fluorescence spectroscopies.


Enero, 2016 | DOI: 10.1002/ppap.201500133

Nanotecnología en Superficies y Plasma

Application of Prussian Blue electrodes for amperometric detection of free chlorine in water samples using Flow Injection Analysis

Salazar, P; Martin, M; Gonzalez-Mora, JL; Gonzalez-Elipe, AR
Talanta, 146 (2016) 410-416

The performance for free chlorine detection of surfactant-modified Prussian Blue screen printed carbon electrodes (SPCEs/PB-BZT) have been assessed by cyclic voltammetry and constant potential amperometry. The characterization of SPCEs/PB-BZT by X-ray photoemission, Raman and infrared spectroscopies confirmed the correct electrodeposition of the surfactant-modified PB film. These electrodes were incorporated in a Flow Injection device and the optimal working conditions determined as a function of experimental variables such as detection potential, electrolyte concentration or flow-rate. The sensor presented a linear response in the range 0–3 ppm free chlorine, with a sensitivity of 16.2 μA ppm−1 cm−2. The limit of detection (LOD) (S/N=3.3) and the limit of quantification (S/N=10) amounted to 8.25 and 24.6 ppb, respectively, adequate for controlling tap and drinking waters. To demonstrate the feasibility of using this free chlorine sensor for real applications possible interferences such as nitrate, nitrite and sulfate ions were successfully tested and discarded. Real free chlorine analysis was carried out in spiked tap water samples and commercial bleaches.


Enero, 2016 | DOI: 10.1016/j.talanta.2015.08.072

Materiales Nanoestructurados y Microestructura

Investigation of a Pt containing washcoat on SiC foam for hydrogen combustion applications

Fernandez, A; Arzac, GM; Vogt, UF; Hosoglu, F; Borgschulte, A; de Haro, MCJ; Montes, O; Zuttel, A
Applied Catalysis B: Environmental, 180 (2016) 336-343

A commercial Pt based washcoat, used for catalytic methane combustion, was studied supported on a commercial SiC foam as catalytic material (Pt/SiC) for catalytic hydrogen combustion (CHC). Structural and chemical characterization was performed using Electron Microscopy, X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The reaction was monitored following water concentration by Fourier Transform Infrared spectra (FTIR). The FTIR method was compared with H2 detection by Gas Cromatography (GC) and has shown to be adequate to study the kinetics of the CHC reaction in steady state under our experimental conditions (very lean 1% (v/v) H2/air mixtures). The catalyst is composed of 5–20 nm disperse Pt nanoparticles decorating a mixture of high surface area Al2O3 and small amounts of ceria supported on the SiC foam which also contains alumina as binder. The Pt/SiC catalytic material has demonstrated to be active enough to start up the reaction in a few seconds at room temperature. The material has been able to convert at least 18.5 Lhydrogen min−1 gPt−1 at room temperature in conditions of excess of catalyst. The Pt/SiC material was studied after use using XPS and no significant changes on Pt oxidation states were found. The material was characterized from a kinetic point of view. From the conversion-temperature plot a T50(temperature for 50% conversion) of 34 °C was obtained. Activation energy measured in our conditions was 35 ± 1 kJ mol−1.


Enero, 2016 | DOI: 10.1016/j.apcatb.2015.06.040

Nanotecnología en Superficies y Plasma

A novel 3D absorption correction method for quantitative EDX-STEM tomography

Burdet, P; Saghi, Z; Filippin, AN; Borras, A; Midgley, PA
Ultramicroscopy, 160 (2016) 118-129

This paper presents a novel 3D method to correct for absorption in energy dispersive X-ray (EDX) microanalysis of heterogeneous samples of unknown structure and composition. By using STEM-based tomography coupled with EDX, an initial 3D reconstruction is used to extract the location of generated X-rays as well as the X-ray path through the sample to the surface. The absorption correction needed to retrieve the generated X-ray intensity is then calculated voxel-by-voxel estimating the different compositions encountered by the X-ray. The method is applied to a core/shell nanowire containing carbon and oxygen, two elements generating highly absorbed low energy X-rays. Absorption is shown to cause major reconstruction artefacts, in the form of an incomplete recovery of the oxide and an erroneous presence of carbon in the shell. By applying the correction method, these artefacts are greatly reduced. The accuracy of the method is assessed using reference X-ray lines with low absorption.


Enero, 2016 | DOI: 10.1016/j.ultramic.2015.09.012

Materiales Nanoestructurados y Microestructura

Disorder-order phase transformation in a fluorite-related oxide thin film: In-situ X-ray diffraction and modelling of the residual stress effects

Gaboriaud, RJ; Paumier, F; Lacroix, B
Thin Solid Films, 601 (2016) 84-88

This work is focused on the transformation of the disordered fluorite cubic-F phase to the ordered cubic-C bixbyite phase, induced by isothermal annealing as a function of the residual stresses resulting from different concentrations of microstructural defects in the yttrium oxide, Y2O3. 

This transformation was studied using in-situ X-ray diffraction and was modelled using Kolmogorov-Johnson-Mehl-Avrami (KJMA) analysis. The degree of the disorder of the oxygen network was associated with the residual stress, which was a key parameter for the stability and the kinetics of the transition of the different phases that were present in the thin oxide film. When the degree of disorder/residual stress level is high, this transition, which occurs at a rather low temperature (300 degrees C), is interpreted as a transformation of phases that occurs by a complete recrystallization via the nucleation and growth of a new cubic-C structure. Using the KJMA model, we determined the activation energy of the transformation process, which indicates that this transition occurs via a one-dimensional diffusion process. Thus, we present the analysis and modelling of the stress state. When the disorder/residual stress level was low, a transition to the quasi-perfect ordered cubic-C structure of the yttrium oxide appeared at a rather high temperature (800 degrees C), which is interpreted as a classic recovery mechanism of the cubic-C structure.


Enero, 2016 | DOI: 10.1016/j.tsf.2015.08.030



2015


Nanotecnología en Superficies y Plasma

"In Operando" X-ray Absorption Spectroscopy Analysis of Structural Changes During Electrochemical Cycling of WO3 and WxSiyOz Amorphous Electrochromic Thin Film Cathodes

Garcia-Garcia, FJ; Gil-Rostra, J; Yubero, F; Espinos, JP; Gonzalez-Elipe, AR; Chaboy, J
Journal of Physical Chemistry C, 119 (2015) 644-652

This work reports a X-ray absorption spectroscopy (XAS) study under in operando conditions of the structural and chemical changes undergone by WO3 and WxSiyOz thin films used as electrochromic cathodes. The electrochromic films were prepared by magnetron sputtering deposition at oblique angles and then characterized by a large variety of techniques. The voltammograms and chronoamperometric diagrams in both aqueous and organic electrolyte media revealed a total reversibility of the electrochromic behavior, a low response time, and a high coloration efficiency for the two types of thin films. The in operando X-ray absorption study of the films working in aqueous solutions revealed that when they were electrochemically cycled the average WO distances reversibly varied by a Delta d of 0.06 and 0.08 angstrom for, respectively, WO3 and WxSiyOz. These changes are discussed by assuming the reduction of W6+ cations and the transformation of W-O double bonds into single WO bond structures during the electrochemical cycling of the films.


Enero, 2015 | DOI: 10.1021/jp508377v

Nanotecnología en Superficies y Plasma

Optical properties of zirconium oxynitride films: The effect of composition, electronic and crystalline structures

Carvalho, P; Borges, J; Rodrigues, MS; Barradas, NP; Alves, E; Espinos, JP; Gonzalez-Elipe, AR; Cunha, L; Marques, L; Vasilevskiy, MI; Vaz, F
Applied Surface Science, 358 (2015) 660-669

This work is devoted to the investigation of zirconium oxynitride (ZrOxNy) films with varied optical responses prompted by the variations in their compositional and structural properties. The films were prepared by dc reactive magnetron sputtering of Zr, using Ar and a reactive gas mixture of N-2 + O-2 ( 17:3). The colour of the films changed from metallic-like, very bright yellow-pale and golden yellow, for low gas flows to red-brownish for intermediate gas flows. Associated to this colour change there was a significant decrease of brightness. With further increase of the reactive gas flow, the colour of the samples changed from red-brownish to dark blue or even to interference colourations. The variations in composition disclosed the existence of four different zones, which were found to be closely related with the variations in the crystalline structure. XRD analysis revealed the change from a B1 NaCl face-centred cubic zirconium nitride-type phase for films prepared with low reactive gas flows, towards a poorly crystallized over-stoichiometric nitride phase, which may be similar to that of Zr3N4 with some probable oxygen inclusions within nitrogen positions, for films prepared with intermediate reactive gas flows. For high reactive gas flows, the films developed an oxynitride-type phase, similar to that of gamma-Zr2ON2 with some oxygen atoms occupying some of the nitrogen positions, evolving to a ZrO2 monoclinic type structure within the zone where films were prepared with relatively high reactive gas flows. The analysis carried out by reflected electron energy loss spectroscopy (REELS) revealed a continuous depopulation of the d-band and an opening of an energy gap between the valence band (2p) and the Fermi level close to 5 eV. The ZrN-based coatings (zone land II) presented intrinsic colourations, with a decrease in brightness and a colour change from bright yellow to golden yellow, red brownish and dark blue. Associated to these changes, there was also a shift of the reflectivity minimum to lower energies, with the increase of the non-metallic content. The samples lying in the two last zones (zone III, oxynitride and zone IV, oxide films) revealed a typical semi-transparent-optical behaviour showing interference-like colourations only due to the complete depopulation of the d band at the Fermi level. The samples lying in these zones presented also an increase of the optical bandgap from 2 to 3.6 eV. 


Diciembre, 2015 | DOI: 10.1016/j.apsusc.2015.09.129

Nanotecnología en Superficies y Plasma

Efficient synthesis of ammonia from N-2 and H-2 alone in a ferroelectric packed-bed DBD reactor

Gomez-Ramirez, A; Cotrino, J; Lambert, RM; Gonzalez-Elipe, AR
Plasma Sources Science and Technology, 24 (2015) 065011

A detailed study of ammonia synthesis from hydrogen and nitrogen in a planar dielectric barrier discharge (DBD) reactor was carried out. Electrical parameters were systematically varied, including applied voltage and frequency, electrode gap, and type of ferroelectric material (BaTiO3 versus PZT). For selected operating conditions, power consumption and plasma electron density were estimated from Lissajous diagrams and by application of the Bolsig + model, respectively. Optical emission spectroscopy was used to follow the evolution of plasma species (NH*, N*, N-2(+) and N-2*) as a function of applied voltage with both types of ferroelectric material. PZT gave both greater energy efficiency and higher ammonia yield than BaTiO3: 0.9 g NH3 kWh(-1) and 2.7% single pass N-2 conversion, respectively. This performance is substantially superior to previously published findings on DBD synthesis of NH3 from N-2 and H-2 alone. The influence of electrical working parameters, the beneficial effect of PZT and the importance of controlling reactant residence time are rationalized in a reaction model that takes account of the principal process variables


Diciembre, 2015 | DOI: 10.1088/0963-0252/24/6/065011

Materiales Nanoestructurados y Microestructura

Atomic scale characterization of SiO2/4H-SiC interfaces in MOSFETs devices

Beltran, AM; Duguay, S; Strenger, C; Bauer, AJ; Cristiano, F; Schamm-Chardon, S
Solid State Communications, 221 (2015) 28-32

The breakthrough of 4H-SiC MOSFETs is stemmed mainly due to the mobility degradation in their channel in spite of the good physical intrinsic material properties. Here, two different n-channel 4H-SiC MOSFETs are characterized in order to analyze the elemental composition at the SiC/SiO2 interface and its relationship to their electrical properties. Elemental distribution analyses performed by EELS reveal the existence of a transition layer between the SiC and the SiO2 regions of the same width for both MOSFETs despite a factor of nearly two between their electron mobility. Additional 3D compositional mapping by atom probe tomography corroborates these results, particularly the absence of an anomalous carbon distribution around the SiC/SiO2interface.


Noviembre, 2015 | DOI: 10.1016/j.ssc.2015.08.017

Nanotecnología en Superficies y Plasma

Plasma reforming of methane in a tunable ferroelectric packed-bed dielectric barrier discharge reactor

Montoro-Damas, AM; Brey, JJ; Rodriguez, MA; Gonzalez-Elipe, AR; Cotrino, J
Journal of Power Sources, 296 (2015) 268-275

In a tunable circular parallel plate dielectric barrier discharge reactor with pellets of a ferroelectric material separating the electrodes we investigate the plasma reforming of methane trying to maximize both the reaction yield and the energetic efficiency of the process. The geometrical configuration of the reactor (gap between electrodes, active electrode area) and the ferroelectric pellet size have been systematically varied to determine their influence on the process efficiency. The comparison between wet (with H2O as reactant), oxidative (with O2), and dry (with CO2) reforming reactions reveals a higher efficiency for the former with CO + H2 as main reaction products. The maximum energetic efficiency EE, defined as the produced number of litres of H2 per kWh, found for optimized working conditions at low-level applied power is higher than the up to date best-known results. A comprehensive discussion of the influence of the different parameters affecting the reaction yield is carried out.


Noviembre, 2015 | DOI: 10.1016/j.jpowsour.2015.07.038

Nanotecnología en Superficies y Plasma - Materiales Ópticos Multifuncionales

Single-step fabrication process of 1-D photonic crystals coupled to nanocolumnar TiO2 layers to improve DSC efficiency

Gonzalez-Garcia, L; Colodrero, S; Miguez, H; Gonzalez-Elipe, AR
Optics Express, 23 (2015) A1642-A1650

The present work proposes the use of a TiO2 electrode coupled to a one-dimensional photonic crystal (1DPC), all formed by the sequential deposition of nanocolumnar thin films by physical vapor oblique angle deposition (PV-OAD), to enhance the optical and electrical performance of DSCs while transparency is preserved. We demonstrate that this approach allows building an architecture combining a non-dispersive 3 µm of TiO2 electrode and 1 µm TiO2-SiO2 1DPC, both columnar, in a single-step process. The incorporation of the photonic structure is responsible for a rise of 30% in photovoltaic efficiency, as compared with a transparent cell with a single TiO2 electrode. Detailed analysis of the spectral dependence of the photocurrent demonstrates that the 1DPC improves light harvesting efficiency by both back reflection and optical cavity modes confinement within the TiO2 films, thus increasing the overall performance of the cell.


Noviembre, 2015 | DOI: 10.1364/OE.23.0A1642

Nanotecnología en Superficies y Plasma

Amperometric magnetobiosensors using poly(dopamine)-modified Fe3O4 magnetic nanoparticles for the detection of phenolic compounds

Martin, M; Salazar, P; Campuzano, S; Villalonga, R; Pingarron, JM; Gonzalez-Mora, JL
Analytical Methods, 7 (2015) 8801-8808

The synthesis of poly(dopamine)-modified magnetic nanoparticles (MNPs) and their application in preparing electrochemical enzyme biosensors that are useful to detect phenolic compounds is reported in this work. MNPs of about 16 nm were synthesized by a co-precipitation method and conveniently modified with poly(dopamine). Non-modified and modified MNPs were characterized using X-ray photoelectron spectroscopy (XPS), Raman and infrared spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM). Horseradish peroxidase (HRP) was covalently immobilized onto the surface of the poly(dopamine)-modified MNPs via Michael addition and/or Schiff base formation and used to construct a biosensor for phenolic compounds by capturing the HRP-modified-nanoparticles onto the surface of a magnetic-modified glassy carbon electrode (GCE). Cyclic voltammetry and amperometry were used to study the electrochemical and analytical properties of the biosensor using hydroquinone (HQ) as a redox probe. Among the different phenolic compounds studied, the biosensor exhibited higher sensitivity for HQ, 1.38 A M−1 cm−2, with limits of detection and quantification of 0.3 and 1.86 μM, respectively. The analytical biosensor performance for HQ and 2-aminophenol compared advantageously with those of previous phenolic biosensors reported in the literature.


Octubre, 2015 | DOI: 10.1039/C5AY01996F

Nanotecnología en Superficies y Plasma

"In situ" XPS studies of laser-induced surface nitridation and oxidation of tantalum

Lahoz, R; Espinos, JP; Yubero, F; Gonzalez-Elipe, AR; de la Fuente, GF
Journal of Materials Research, 30 (2015) 2967-2976

This work studies the nitridation of Ta by laser irradiation by means of x-ray photoelectron spectroscopy. The study has been carried out under "in situ" conditions by controlling the nitrogen partial pressure, the presence of traces of oxygen, and the irradiance of the laser. It is found that a thin layer of Ta2O5 is directly obtained when irradiating in the presence of oxygen, while a Ta3N5 surface compound and some minor contributions of nonstoichiometric phases are formed in the presence of nitrogen. For O-2:N-2 mixtures at 0.1 Pa, preferential nitride formation occurs up to a ratio of 1:4, while Ta2O5 starts to be predominant for ratios above this value. The air stability of the tantalum nitride layer formed by laser irradiation and the surface topography of the irradiated metal are also studied. The possible factors determining this behavior are discussed.


Octubre, 2015 | DOI: 10.1557/jmr.2015.190

Materiales Nanoestructurados y Microestructura - Materiales Ópticos Multifuncionales

Full solution processed mesostructured optical resonators integrating colloidal semiconductor quantum dots

Calvo, ME; Hidalgo, N; Schierholz, R; Kovacs, A; Fernandez, A; Bellino, MG; Soler-Illia, GJAA; Miguez, H
Nanoscale, 7 (2015) 16583-16589

Herein we show a solution based synthetic pathway to obtain a resonant optical cavity with embedded colloidal semiconductor quantum dots (CSQDs). The optical cavity pore network, surrounded by two dense Bragg mirrors, was designed ad hoc to selectively host the quantum dots, while uncontrolled infiltration of those in the rest of the layered structure was prevented. Coupling between the optical resonant modes of the host and the natural emission of the embedded nanoparticles gives rise to the fine tuning of the luminescence spectrum extracted from the ensemble. Our approach overcomes, without the need for an encapsulating agent and exclusively by solution processing, the difficulties that arise from the low thermal and chemical stability of the CSQDs. It opens the route to achieving precise control over their location and hence over the spectral properties of light emitted by these widely employed nanomaterials. Furthermore, as the porosity of the cavity is preserved after infiltration, the system remains responsive to environmental changes, which provides an added value to the proposed structure.


Octubre, 2015 | DOI: 10.1039/C5NR03977K

Materiales Nanoestructurados y Microestructura

Role of Y in the oxidation resistance of CrAlYN coatings

Dominguez-Meister, S; El Mrabet, S; Escobar-Galindo, R; Mariscal, A; de Haro, CJ; Justo, A; Brizuela, M; Rojas, TC; Sanchez-Lopez, JC
Applied Surface Science, 363 (2015) 504-511

CrAlYN coatings with different aluminum (4–12 at.%) and yttrium (2–5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N2 mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron microscopy (X-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GD-OES). The sequential exposure to the metallic targets during the synthesis leads to a multilayer structure where concentration of metallic elements (Cr, Al and Y) is changing periodically. A good oxidation resistance is observed when Al- and Y-rich regions are separated by well-defined CrN layers, maintaining crystalline coherence along the columnar structure. This protective behavior is independent of the type of substrate and corresponds to the formation of a thin mixed (Al, Cr)-oxide scale that protects the film underneath. The GD-OES and XRD analysis have demonstrated that Y acts as a reactive element, blocking the Fe and C atoms diffusion from the steel and favoring higher Al/Cr ratio in the passivation layer after heating. The coating with Y content around 4 at.% exhibited the best performance with a thinner oxide scale, a delay in the CrN decomposition and transformation to Cr2N, and a more effective Fe and C blocking.


Octubre, 2015 | DOI: 10.1016/j.apsusc.2015.06.099

Nanotecnología en Superficies y Plasma

Physiological Degradation Mechanisms of PLGA Membrane Films under Oxygen Plasma Treatment

Lopez-Santos, C; Terriza, A; Portoles, J; Yubero, F; Gonzalez-Elipe, AR
Journal fo Physical Chemistry C, 119 (2015) 20446–20452

Degradation under simulated physiological conditions of poly(lactic-co-glycolic) (PLGA) copolymer membrane films subjected to an oxygen plasma treatment compared to its “as prepared” state has been studied by gas cluster ion beam assisted X-ray photoelectron spectroscopy for chemical depth profiling analysis. This investigation is complemented with atomic force microscopy, weight loss measurements, and visual inspection of the films at the different stages of the degradation process. The obtained results show that the carbon functional groups of the PLGA membrane films undergo a heterogeneous hydrolytic degradation to different rates depending on the plasma pretreatment. The content of glycolic groups (GA) in untreated PLGA samples immersed for 3 weeks in a phosphate-buffered saline solution decreased at the surface, whereas the ratio between glycolic and lactic units (LA) did not vary in the inner regions (∼400 nm depth) of the degraded membrane films. By contrast, oxygen plasma pretreatment enhances the degradation efficiency and causes that both lactic and glycolic functional components decreased at the surface and in the interior of the film, although with less prevalence for the lactic units that present a comparatively higher resistance to degradation.


Septiembre, 2015 | DOI: 10.1021/acs.jpcc.5b05011

Nanotecnología en Superficies y Plasma

Microstructure of mixed oxide thin films prepared by magnetron sputtering at oblique angles

Gil-Rostra, J; Garcia-Garcia, FJ; Ferrer, FJ; Gonzalez-Elipe, AR; Yubero, F
Thin Solid Films, 591 (2015) 330-335

Several mixed oxide thin film series of samples (Si–Co–O, Si–Ni–O, Si–W–O) have been prepared by reactive magnetron sputtering at oblique angle geometries. The paper focuses on the description of microstructure of the films as a function of their stoichiometry. It is found that for identical process parameters (gas mixture, pressure, magnetron-substrate distance, incidence angle of the vapour flux, etc.) the tilt angle of the developed columnar microstructure and the film porosity is strongly dependent on the stoichiometry of the films. The results are discussed in the framework of several theoretical models on this topic.


Septiembre, 2015 | DOI: 10.1016/j.tsf.2015.01.058

Materiales Nanoestructurados y Microestructura

Direct observation of doping incorporation pathways in self-catalytic GaMnAs

Kasama, T.; Thuvander, M.; Siusys, A.; Gontard, L. C.; Kovacs, A.; Yazdi, S.; Duchamp, M.; Gustafsson, A.; Dunin-Borkowski, R. E.; Sadowski, J.
Journal of Applied Physics, 118 (2015) 054302

Doping mechanisms of Mn in GaAs nanowires (NWs) that have been grown self-catalytically at 600 °C by molecular beam epitaxy (MBE) are investigated using advanced electron microscopy techniques and atom probe tomography. Mn is found to be incorporated primarily in the form of non-magnetic tetragonal Ga0.82Mn0.18 nanocrystals in Ga catalyst droplets at the ends of the NWs, while trace amounts of Mn (22 ± 4 at. ppm) are also distributed randomly in the NW bodies without forming clusters or precipitates. The nanocrystals are likely to form after switching off the reaction in the MBE chamber, since they are partially embedded in neck regions of the NWs. The Ga0.82Mn0.18 nanocrystals and the low Mn concentration in the NW bodies are insufficient to induce a ferromagnetic phase transition, suggesting that it is difficult to have high Mn contents in GaAs even in 1-D NW growth via the vapor-liquid-solid process.


Agosto, 2015 | DOI: 10.1063/1.4927623

Nanotecnología en Superficies y Plasma

Rapid Legionella pneumophila determination based on a disposable core–shell Fe3O4@poly(dopamine) magnetic nanoparticles immunoplatform

Martin, M; Salazar, P; Jimenez, C; Lecuona, M; Ramos, MJ; Ode, J; Alcoba, J; Roche, R; Villalonga, R; Campuzano, S; Pingarron, JM; Gonzalez-Mora, JL
Analytica Chimica Acta, 887 (2015) 51-58

A novel amperometric magnetoimmunoassay, based on the use of core–shell magnetic nanoparticles and screen-printed carbon electrodes, was developed for the selective determination of Legionella pneumophila SG1. A specific capture antibody (Ab) was linked to the poly(dopamine)–modified magnetic nanoparticles (MNPs@pDA-Ab) and incubated with bacteria. The captured bacteria were sandwiched using the antibody labeled with horseradish peroxidase (Ab-HRP), and the resulting MNPs@pDA-Ab-Legionella neumophila-Ab-HRP were captured by a magnetic field on the electrode surface. The amperometric response measured at −0.15 V vs. Ag pseudo-reference electrode of the SPCE after the addition of H2O2 in the presence of hydroquinone (HQ) was used as transduction signal. The achieved limit of detection, without pre-concentration or pre-enrichment steps, was 104 Colony Forming Units (CFUs) mL−1. The method showed a good selectivity and the MNPs@pDA-Ab exhibited a good stability during 30 days. The possibility of detecting L. pneumophila at 10 CFU mL−1 level in less than 3 h, after performing a membrane-based preconcentration step, was also demonstrated.


Agosto, 2015 | DOI: 10.1016/j.aca.2015.05.048

Nanotecnología en Superficies y Plasma

Ultraviolet Pretreatment of Titanium Dioxide and Tin-Doped Indium Oxide Surfaces as a Promoter of the Adsorption of Organic Molecules in Dry Deposition Processes: Light Patterning of Organic Nanowires

Oulad-Zian, Y; Sanchez-Valencia, JR; Parra-Barranco, J; Hamad, S; Espinos, JP; Barranco, A; Ferrer, J; Coll, M; Borras, A
Langmuir, 31 (2015) 8294-8302

In this article we present the preactivation of TiO2 and ITO by UV irradiation under ambient conditions as a tool to enhance the incorporation of organic molecules on these oxides by evaporation at low pressures. The deposition of p-stacked molecules on TiO2 and ITO at controlled substrate temperature and in the presence of Ar is thoroughly followed by SEM, UV-vis, XRD, RBS, and photoluminescence spectroscopy, and the effect is exploited for the patterning formation of small-molecule organic nanowires (ONWs). X-ray photoelectron spectroscopy (XPS) in situ experiments and molecular dynamics simulations add critical information to fully elucidate the mechanism behind the increase in the number of adsorption centers for the organic molecules. Finally, the formation of hybrid organic/inorganic semiconductors is also explored as a result of the controlled vacuum sublimation of organic molecules on the open thin film microstructure of mesoporous TiO2.


Agosto, 2015 | DOI: 10.1021/acs.langmuir.5b01572

Nanotecnología en Superficies y Plasma

Modulating Low Energy Ion Plasma Fluxes for the Growth of Nanoporous Thin Films

Alvarez, Rafael; Lopez-Santos, Carmen; Ferrer, Francisco J.; Rico, Victor; Cotrino, Jose; Gonzalez-Elipe, Agustin R.; Palmero, Alberto
Plasma Processes and Polymers, 12 (2015) 719-724

The growth of nanoporous layers by plasma-assisted deposition techniques is strongly mediated by the ion fluxes in the reactor. To analyze their influence we have deposited different nanostructured thin films by the magnetron sputtering technique at oblique angles, modulating the ion fluxes in the plasma by tuning the frequency of the electromagnetic signal from pure DC to 160 kHz DC pulsed mode. In the DC case, ions possess energies below 5 eV and do not induce noticeable changes in the film structure. However, when the signal is pulsed, ions with energies up to 40 eV impinge on the film, decreasing the porosity of the layers and tilting down the porous/nanocolumnar structures. As a result, we demonstrate that the overall porosity of the layers and the tilt angle of the columns can be tailored as two independent morphological quantities.


Agosto, 2015 | DOI: 10.1002/ppap.201400209

Nanotecnología en Superficies y Plasma

A novel and improved surfactant-modified Prussian Blue electrode for amperometric detection of free chlorine in water

Salazar, Pedro; Martin, Miriam; Garcia-Garcia, Francisco J.; Luis Gonzalez-Mora, Jose; Gonzalez-Elipe, Agustin R.
Sensors and Actuators B: Chemical, 213 (2015) 116-123

A surfactant-modified Prussian Blue (PB) electrochemical sensor has been developed. Benzethonium was used to assist the electrodeposition of PB onto a glassy carbon electrode (GCE). The surface coverage ( [View the MathML source] ) was 7.75 × 10−8 mol cm−2, five times higher than the value obtained in the absence of surfactant, and the film thickness of ca. 123 nm. SEM, EDX, Raman were used to characterize the electrodes while their electrochemical analysis proved a superior performance for the surfactant modified PB film. Cyclic voltammetry and amperometry were used to study the sensor ability to detect chlorine, and the main experimental variables were optimized. Under optimized conditions, the sensor presented a sensitivity of 12 μA ppm−1 cm−2, a linear range from 9 ppb to 10 ppm and a reproducibility of 4.2%. For the first time, we proved the sensor performance for real applications. Thus, chlorine was determined in tap water and the obtained concentrations validated with a standard colorimetric method. The obtained results showed that our sensor is highly performant and reliable for applications involving determinations of environmental residual chlorine.


Julio, 2015 | DOI: 10.1016/j.snb.2015.02.092

Materiales Nanoestructurados y Microestructura

Fabrication of Optical Multi layer Devices from Porous Silicon Coatings with Closed Porosity by Magnetron Sputtering

Caballero-Hernandez, Jaime; Godinho, Vanda; Lacroix, Bertrand; Jimenez de Haro, Maria C.; Jamon, Damien; Fernandez, Asuncion
ACS Applied Materials & Interfaces, 7 (2015) 13880-13897

The fabrication of single-material photonic-multilayer devices is explored using a new methodology to produce porous silicon layers by magnetron sputtering. Our bottom-up methodology produces highly stable amorphous porous silicon films with a controlled refractive index using magnetron sputtering and incorporating a large amount of deposition gas inside the closed pores. The influence of the substrate bias on the formation of the closed porosity was explored here for the first time when He was used as the deposition gas. We successfully simulated, designed, and characterized Bragg reflectors and an optical microcavity that integrates these porous layers. The sharp interfaces between the dense and porous layers combined with the adequate control of the refractive index and thickness allowed for excellent agreement between the simulation and the experiments. The versatility of the magnetron sputtering technique allowed for the preparation of these structures for a wide range of substrates such as polymers while also taking advantage of the oblique angle deposition to prepare Bragg reflectors with a controlled lateral gradient in the stop band wavelengths.


Julio, 2015 | DOI: 10.1021/acsami.5b02356

Materiales Nanoestructurados y Microestructura

Removing the effects of the "dark matter" in tomography

Gontard, Lionel C.
Ultramicroscopy, 154 (2015) 64-72

Electron tomography (ET) using different imaging modes has been progressively consolidating its position as a key tool in materials science. The fidelity of a tomographic reconstruction, or tomogram, is affected by several experimental factors. Most often, an unrealistic cloud of intensity that does not correspond to a real material phase of the specimen ("dark matter") blurs the tomograms and enhances artefacts arising from the missing wedge (MW). Here we show that by simple preprocessing of the background level of any tomographic tilt series, it is possible to minimise the negative effects of that "dark matter". Iterative reconstruction algorithms converge better, leading to tomograms with fewer streaking artefacts from the MW, more contrast, and increased accuracy. The conclusions are valid irrespective of the imaging mode used, and the methodology improves the segmentation and visualisation of tomograms of both crystalline and amorphous materials. We show examples of HAADF STEM and BF TEM tomography.


Julio, 2015 | DOI: 10.1016/j.ultramic.2015.03.017

Nanotecnología en Superficies y Plasma

New Copper wide range nanosensor electrode prepared by physical vapor deposition at oblique angles for the non-enzimatic determination of glucose

Salazar, P; Rico, V; Rodriguez-Amaro, R; Espinos, JP; Gonzalez-Elipe, AR
Electrochimica Acta, 169 (2015) 195-201

In this work a novel Cu nanostructured electrode is presented. Cu tilted nanocolumnar and porous thin films have been prepared by physical vapor deposition (PVD) in an oblique angle configuration and characterized by different techniques. Cyclic voltammetry and amperometry were used to study the sensing ability of the copper films deposited on ITO to quantitatively determine glucose and to optimize the experimental conditions of detection. Scanning electron microscopy data revealed that the film microstructure consists of tilted nanocolumns of around 70 nm of diameter and an inclination of 65° with respect to the surface normal that extend through the total thickness of the layer of ca. 300 nm. X ray photoelectron spectroscopy and Raman, used to determine the oxidation state of Cu, revealed that an oxy/hydroxide external layer formed around the nanocolumns is the active phase responsible for the electrocatalytic detection of glucose. Under optimized conditions, the CuO/Cu nanoporous/ITO electrode presented a sensitivity of 1.41 A mol dm−3 cm−2 (R2:0.999) with a limit of detection of 0.36 μmol dm−3 and a reproducibility of 3.42%.The selectivity of the proposed sensor was checked against various interferences, including physiological compounds, different sugars and ethanol, thereby showing excellent anti-interference properties. The CuO/Cu nanoporous/ITO electrode was also used successfully to determine glucose in blood samples showing a performance comparable to that of a commercial glucometer. An extended working range covering from 1 to 5 × 10−3 mol dm−3 was determined for these sensor films which, in this way, could be applied for different analytical purposes including agro industrial liquids.


Julio, 2015 | DOI: 10.1016/j.electacta.2015.04.092

Nanotecnología en Superficies y Plasma

Nanocolumnar 1-dimensional TiO2 photoanodes deposited by PVD-OAD for perovskite solar cell fabrication

Javier Ramos, F.; Oliva-Ramirez, Manuel; Nazeeruddin, Mohammad Khaja; Graetzel, Michael; Gonzalez-Elipe, Agustin R.; Ahmad, Shahzada
Journal of Materials Chemistry A, 3 (2015) 13291-13298

Perovskite solar cells have attracted increasing interest among the photovoltaic community in the last few years owing to their unique properties and high efficiency. In the present work, we report the fabrication of perovskite solar cells based on highly ordered 1-dimensional porous TiO2 photoanodes, which are uniform on a large area. These nanocolumnar porous TiO2 photoanodes were deposited by physical vapor deposition in an oblique angle configuration (PVD-OAD) by varying the zenithal angle between the target and the substrate normal. Perovskite infiltration into these 1-dimensional nanocolumnar structures was homogeneous through the entire thickness of the porous layer as revealed by secondary ion mass spectroscopy studies. The fabricated solar cells, with an optimized thickness of the photoanode and with industrially accepted methods, will pave the way for easy implementation on a large scale.


Julio, 2015 | DOI: 10.1039/c5ta02238j

Materiales Nanoestructurados y Microestructura

Island-type growth of Au–Pt heterodimers: direct visualization of misfit dislocations and strain-relief mechanisms

Garcia-Negrete, CA; Knappett, BR; Schmidt, FP; Rojas, TC; Wheatley, AEH; Hofer, F; Fernandez, A
RSC Advances, 5 (2015) 55262-55268

Structural and analytical characterization related to the formation mechanism of Au–Pt heterodimers from polyhedral Pt nanocrystals is reported. The observation of specific lattice strain effects and the emergence of misfit dislocations point to the relevance of the Stranski–Krastanov growth mode as a means of explaining the previously reported dimerisation reaction between Au and Pt. Two size-dependent strain relief mechanisms were identified. For dimers grown from 4.7 nm seeds, the mechanism is related to bulk lattice strain accumulation at {111} planes along with lattice relaxation effects on other crystalline planes. However, for dimers grown from 11.2 nm seed sizes, the formation of misfit dislocations proved to be a highly efficient mechanism by which to release interface mismatch strain. Nanoscale chemical mapping at Au–Pt interfaces also revealed Au–Pt alloying to be unlikely under the mild temperature conditions employed in this work for Au–Pt heterodimer synthesis.


Junio, 2015 | DOI: 10.1039/C5RA09808D

Nanotecnología en Superficies y Plasma

Core-shell polydopamine magnetic nanoparticles as sorbent in micro-dispersive solid-phase extraction for the determination of estrogenic compounds in water samples prior to high-performance liquid chromatography-mass spectrometry analysis

Socas-Rodriguez, B; Hernandez-Borges, J; Salazar, P; Martin, M; Rodriguez-Delgado, MA
Journal of Chromatography A, 1397 (2015) 1-10

In this work, core-shell Fe3O4@poly(dopamine) magnetic nanoparticles (m-NPs) were prepared and characterized in our laboratory and applied as sorbents for the magnetic-micro solid phase extraction (m-mu SPE) of twelve estrogenic compounds of interest (i.e. 17 alpha-estradiol, 17 beta-estradiol, estrone, hexestrol, 17 alpha-ethynylestradiol, diethylstibestrol, dienestrol, zearalenone, alpha-zearalanol,beta-zearalanol, alpha-zearalenol and beta-zearalenol) from different water samples. Separation, determination and quantification were achieved by high-performance liquid chromatography coupled to ion trap mass spectrometry with electrospray ionization. NPs@poly(dopamine) were synthesized by a chemical coprecipitation procedure and characterized by different surface characterization techniques (X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, transmission and scanning electron microscopy, infrared and Raman spectroscopy, vibrating sample magnetometry, microelectrophoresis and adsorption/desorption isotherms). Parameters affecting the extraction efficiency of m-mu SPE (i.e. polymerization time, pH of the sample, extraction and elution conditions) were studied and optimized. The methodology was validated for Milli-Q, mineral, tap and wastewater using 2-methoxyestradiol as internal standard, obtaining recoveries ranging from 70 to 119% with relative standard deviation values lower than 20% and limits of quantification in the range 0.02-1.1 mu g/L.


Junio, 2015 | DOI: 10.1016/j.chroma.2015.04.010

Nanotecnología en Superficies y Plasma

Porous, robust highly conducting Ni-YSZ thin film anodes prepared by magnetron sputtering at oblique angles for application as anodes and buffer layers in solid oxide fuel cells

Garcia-Garcia, Francisco J.; Yubero, Francisco; Gonzalez-Elipe, Agustin R.; Balomenou, Stella P.; Tsiplakides, Dimitris; Petrakopoulou, Ioanna; Lambert, Richard M.
Inernational Journal of Hydrogen Energy, 40 (2015) 7382-7387

Uniform, highly porous, columnar thin films incorporating YSZ and NiO prepared by magnetron sputtering with deposition at glancing incidence exhibited stoichiometries close to that of the Y-Zr-Ni sputter target. Characterization by means of SEM, XRD, XPS and RBS revealed that the uniformly distributed nickel component in the as-deposited films consisted of NiO, and that the YSZ component was essentially amorphous. Annealing such films at 850 degrees C in hydrogen resulted in crystallization of the YSZ phase with preservation of the columnar morphology, while the NiO underwent reduction to metallic Ni, which partially segregated to the film surface. The hydrogen-annealed thin film anodes exhibited high conductivity, comparable to that of conventionally-prepared anodes, in both hydrogen and hydrogen/water mixtures at temperatures relevant to SOFC operation. They were also robust against strain-induced separation from the substrate under limited thermal cycling in both oxidizing and reducing atmospheres and are promising candidates for use as anodes in their own right and as strain-accommodating buffer layers between conventional anodes and the electrolyte for use in SOFC applications.


Junio, 2015 | DOI: 10.1016/j.ijhydene.2015.04.001

Nanotecnología en Superficies y Plasma

Free-Base Carboxyphenyl Porphyrin Films Using a TiO2 Columnar Matrix: Characterization and Application as NO2 Sensors

Roales, Javier; Pedrosa, Jose M.; Guillen, Maria G.; Lopes-Costa, Tania; Castillero, Pedro; Barranco, Angel; Gonzalez-Elipe, Agustin R.
Sensors, 15 (2015) 11118-11132

The anchoring effect on free-base carboxyphenyl porphyrin films using TiO2 microstructured columns as a host matrix and its influence on NO2 sensing have been studied in this work. Three porphyrins have been used: 5-(4-carboxyphenyl)10,15,20-triphenyl-21H,23H-porphyrin (MCTPP); 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,23H-porphyrin (p-TCPP); and 5,10,15,20-tetrakis(3-carboxyphenyl)-21H,23H-porphyrin (m-TCPP). The analysis of UV-Vis spectra of MCTPP/TiO2, p-TCPP/TiO2 and m-TCPP/TiO2 composite films has revealed that m-TCPP/TiO2 films are the most stable, showing less aggregation than the other porphyrins. IR spectroscopy has shown that m-TCPP is bound to TiO2 through its four carboxylic acid groups, while p-TCPP is anchored by only one or two of these groups. MCTPP can only be bound by one carboxylic acid. Consequently, the binding of p-TCPP and MCTPP to the substrate allows them to form aggregates, whereas the more fixed anchoring of m-TCPP reduces this effect. The exposure of MCTPP/TiO2, p-TCPP/TiO2 and m-TCPP/TiO2 films to NO2 has resulted in important changes in their UV-Vis spectra, revealing good sensing capabilities in all cases. The improved stability of films made with m-TCPP suggests this molecule as the best candidate among our set of porphyrins for the fabrication of NO2 sensors. Moreover, their concentration-dependent responses upon exposure to low concentrations of NO2 confirm the potential of m-TCPP as a NO2 sensor.


Mayo, 2015 | DOI: 10.3390/s150511118

Nanotecnología en Superficies y Plasma

Electrochemical activation of an oblique angle deposited Cu catalyst film for H-2 production

Gonzalez-Cobos, J; Rico, VJ; Gonzalez-Elipe, AR; Valverde, JL; de Lucas-Consuegra, A
Catalysis Science & Technology, 5 (2015) 2203-2214

A novel Cu catalyst film was prepared by oblique angle physical vapour deposition (OAD) on a K-βAl2O3 solid electrolyte (alkaline ionic conductor) for catalytic/electrocatalytic purposes. This technique allowed us to obtain a highly porous and electrically conductive Cu catalyst electrode which was tested in the partial oxidation of methanol (POM) reaction for H2 production and its catalytic activity was in situ enhanced via electrochemical promotion of catalysis (EPOC). The electropromotional effect was reversible and reproducible, and allowed us to increase both hydrogen and methyl formate production rates by almost three times under optimal promotion conditions (320 °C, 2.2 × 10−7 mol of K+ transferred). The observed promotional effect was attributed to a decrease in the Cu catalyst work function as a consequence of the controlled migration of electropositive K+ ions which favoured the chemisorption of electron acceptor molecules (O2) at the expense of the electron donor ones (CH3OH). Under the reaction conditions these ions formed some kinds of potassium surface compounds as demonstrated by SEM, EDX and XPS post-reaction characterization analyses. The obtained results demonstrate the interest of the used catalyst-electrode preparation technique for the electrochemical activation of non-noble metal catalyst films.


Mayo, 2015 | DOI: 10.1039/c4cy01524j

Nanotecnología en Superficies y Plasma

Anisotropic In-Plane Conductivity and Dichroic Gold Plasmon Resonance in Plasma-Assisted ITO Thin Films e-Beam-Evaporated at Oblique Angles

Parra-Barranco, Julian; Garcia-Garcia, Francisco J.; Rico, Victor; Borras, Ana; Lopez-Santos, Carmen; Frutos, Fabian; Barranco, Angel; Gonzalez-Elipe, Agustin R.
ACS Applied Materials & Interfaces, 7 (2015) 10993-11001

ITO thin films have been prepared by electron beam evaporation at oblique angles (OA), directly and while assisting their growth with a downstream plasma. The films microstructure, characterized by scanning electron microscopy, atomic force microscopy, and glancing incidence small-angle X-ray scattering, consisted of tilted and separated nanostructures. In the plasma assisted films, the tilting angle decreased and the nanocolumns became associated in the form of bundles along the direction perpendicular to the flux of evaporated material. The annealed films presented different in-depth and sheet resistivity as confirmed by scanning conductivity measurements taken for the individual nanocolumns. In addition, for the plasma-assisted thin films, two different sheet resistance values were determined by measuring along the nanocolumn bundles or the perpendicular to it. This in-plane anisotropy induces the electrochemical deposition of elongated gold nanostructures. The obtained Au-ITO composite thin films were characterized by anisotropic plasmon resonance absorption and a dichroic behavior when examined with linearly polarized light.


Mayo, 2015 | DOI: 10.1021/acsami.5b02197

Materiales y Procesos Catalíticos de Interés Ambiental y Energético - Nanotecnología en Superficies y Plasma

Theory and Practice: Bulk Synthesis of C3B and its H2- and Li-Storage Capacity

King, TC; Matthews, PD; Glass, H; Cormack, JA; Holgado, JP; Leskes, M; Griffin, JM; Scherman, OA; Barker, PD; Grey, CP; Dutton, SE; Lambert, RM; Tustin, G; Alavi, A; Wright, DS
Angewandte Chemie International Edition, 54 (2015) 5919-5923

Previous theoretical studies of C3B have suggested that boron-doped graphite is a promising H2- and Li-storage material, with large maximum capacities. These characteristics could lead to exciting applications as a lightweight H2-storage material for automotive engines and as an anode in a new generation of batteries. However, for these applications to be realized a synthetic route to bulk C3B must be developed. Here we show the thermolysis of a single-source precursor (1,3-(BBr2)2C6H4) to produce graphitic C3B, thus allowing the characteristics of this elusive material to be tested for the first time. C3B was found to be compositionally uniform but turbostratically disordered. Contrary to theoretical expectations, the H2- and Li-storage capacities are lower than anticipated, results that can partially be explained by the disordered nature of the material. This work suggests that to model the properties of graphitic materials more realistically, the possibility of disorder must be considered.


Mayo, 2015 | DOI: 10.1002/anie.201412200

Materiales Nanoestructurados y Microestructura

STEM-in-SEM high resolution imaging of gold nanoparticles and bivalve tissues in bioaccumulation experiments

C.A. García-Negrete; M.C. Jiménez de Haro; J. Blasco; M. Soto; A. Fernández
Analyst, 140 (2015) 3082-3089

The methodology termed scanning transmission electron microscopy in scanning electron microscopy (STEM-in-SEM) has been used in this work to study the uptake of citrate stabilized gold nanoparticles (AuNPs) (average particle sizes of 23.5 ± 4.0 nm) into tissue samples uponin vitro exposure of the dissected gills of the Ruditapes philippinarum marine bivalve to the nanoparticle suspensions. The STEM-in-SEM methodology has been optimized for achieving optimum resolution under SEM low voltage operating conditions (20–30 kV). Based on scanning microscope assessments and resolution testing (SMART), resolutions well below 10 nm were appropriately achieved by working at magnifications over 100k×, with experimental sample thickness between 300 and 200 nm. These relatively thick slices appear to be stable under the beam and help avoid NP displacement during cutting. We herein show that both localizing of the internalized nanoparticles and imaging of ultrastructural disturbances in gill tissues are strongly accessible due to the improved resolution, even at sample thicknesses higher than those normally employed in standard TEM techniques at higher voltages. Ultrastructural imaging of bio-nano features in bioaccumulation experiments have been demonstrated in this study.


Mayo, 2015 | DOI: 10.1039/C4AN01643B

Materiales Nanoestructurados y Microestructura

Self-lubricity of WSex nanocomposite coatings

S. Dominguez-Meister; M. Conte; A. Igartua; T.C. Rojas; J.C. Sánchez-López
ACS Applied Materials & Interfaces, 7 (2015) 7979-7986

Transition metal chalcogenides with lamellar structure are known for their use in tribological applications although limited to vacuum due to their easy degradation in the presence of oxygen and/or moisture. Here we present a tailored WSex coating with low friction (0.07) and low wear rates (3 × 10–7 mm3 Nm–1) even in ambient air. To understand the low friction behavior and lower chemical reactivity a tribological study is carried out in a high-vacuum tribometer under variable pressure (atmospheric pressure to 1 × 10–8 mbar). A detailed investigation of the film nanostructure and composition by advanced transmission electron microscopy techniques with nanoscale resolution determined that the topmost layer is formed by nanocrystals of WSe2 embedded in an amorphous matrix richer in W, a-W(Se). After the friction test, an increased crystalline order and orientation of WSe2 lamellas along the sliding direction were observed in the interfacial region. On the basis of high angle annular dark field, scanning transmission electron microscopy, and energy dispersive X-ray analysis, the release of W atoms from the interstitial basal planes of the a-W(Se) phase is proposed. These W atoms reaching the surface, play a sacrificial role preventing the lubricant WSe2 phase from oxidation. The increase of the WSe2 crystalline order and the buffer effect of W capturing oxygen atoms would explain the enhanced chemical and tribological response of this designed nanocomposite material.


Abril, 2015 | DOI: 10.1021/am508939s

Materiales Nanoestructurados y Microestructura

Hydrogen production through sodium borohydride ethanolysis

Arzac, GM; Fernandez, A
International Journal of Hydrogen Energy, 40 (2015) 5326-5332

In this work, sodium borohydride (SB) ethanolysis was explored for the first time as a method to generate hydrogen for Polymer Exchange Membrane Fuel Cells. Ethanolysis by-product was characterized by Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, and Nuclear Magnetic Resonance. Metal and acid catalysts were tested. RuCl3 center dot 3H(2)O was the best metal catalyst. Acetic acid was selected for the study because of its effectiveness, low cost and relative greenness. The maximum gravimetric hydrogen density obtained was 2.1% wt. The addition of water produces an increase in hydrogen generation rate and a decrease in conversion. The use of ethanol-methanol mixtures produces an increase in reaction rates in absence of catalyst. As a proof of concept the reaction was performed in a small reactor which operates by the addition of ethanolic acetic acid solutions to solid SB (in the form of granules). The reactor produces stable and constant hydrogen generation in the range of 20-80 ml min(-1) during 1 h at constant temperature (around 27-35 degrees.


Abril, 2015 | DOI: 10.1016/j.ijhydene.2015.01.115

Materiales Nanoestructurados y Microestructura

Transmission electron microscopy of thiol-capped Au clusters on C: Structure and electron irradiation effects

Lionel C. Gontard, Rafal E. Dunin-Borkowski
Micron

High-resolution transmission electron microscopy is used to study interactions between thiol-capped Au clusters and amorphous C support films. The morphologies of the clusters are found to depend both on their size and on the local structure of the underlying C. When the C is amorphous, larger Au clusters are crystalline, while smaller clusters are typically disordered. When the C is graphitic, the Au particles adopt either elongated shapes that maximize their contact with the edge of the C film or planar arrays when they contain few Au atoms. We demonstrate the influence of electron beam irradiation on the structure, shape and stability of the Au clusters, as well as on the formation of holes bounded by terraces of graphitic lamellae in the underlying C.


Marzo, 2015 | DOI: 10.1016/j.micron.2014.12.001

Materiales Nanoestructurados y Microestructura

High N-content a-C:N films elaborated by femtosecond PLD with plasma assistance

Maddi, C; Donnet, C; Loir, AS; Tite, T; Barnier, V; Rojas, TC; Sanchez-Lopez, JC; Wolski, K; Garrelie, F
Applied Surface Science, 332 (2015) 346-353

Amorphous carbon nitride (a-C:N) thin films are a interesting class of carbon-based electrode materials. Therefore, synthesis and characterization of these materials have found lot of interest in environmental analytical microsystems. Herein, we report the nitrogen-doped amorphous carbon thin film elaboration by femtosecond pulsed laser deposition (fs-PLD) both with and without a plasma assistance. The chemical composition and atomic bonding configuration of the films were investigated by multi-wavelength (MW) Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron energy-loss spectroscopy (EELS). The highest nitrogen content, 28 at.%, was obtained with plasma assistance. The I(D)/I(G) ratio and the G peak position increased as a function of nitrogen concentration, whereas the dispersion and full width at half maximum (FWHM) of G peak decreased. This indicates more ordered graphitic like structures in the films both in terms of topological and structural, depending on the nitrogen content. EELS investigations were correlated with MW Raman results. The interpretation of XPS spectra of carbon nitride films remains a challenge. Plasma assisted PLD in the femtosecond regime led to a significant high nitrogen concentration, which is highlighted on the basis of collisional processes in the carbon plasma plume interacting with the nitrogen plasma.


Marzo, 2015 | DOI: 10.1016/j.apsusc.2015.01.123

Nanotecnología en Superficies y Plasma

Nanocolumnar coatings with selective behavior towards osteoblast and Staphylococcus aureus proliferation

Izquierdo-Barba, Isabel; Miguel Garcia-Martin, Jose; Alvarez, Rafael; Palmero, Alberto; Esteban, Jaime; Perez-Jorge, Concepcion; Arcos, Daniel; Vallet-Regi, Maria
Acta Biomaterialia, 15 (2015) 20-28

Bacterial colonization and biofilm formation on orthopedic implants is one of the worst scenarios in orthopedic surgery, in terms of both patient prognosis and healthcare costs. Tailoring the surfaces of implants at the nanoscale to actively promote bone bonding while avoiding bacterial colonization represents an interesting challenge to achieving better clinical outcomes. Herein, a Ti6Al4V alloy of medical grade has been coated with Ti nanostructures employing the glancing angle deposition technique by magnetron sputtering. The resulting surfaces have a high density of nanocolumnar structures, which exhibit strongly impaired bacterial adhesion that inhibits biofilm formation, while osteoblasts exhibit good cell response with similar behavior to the initial substrates. These results are discussed on the basis of a "lotus leaf effect" induced by the surface nanostructures and the different sizes and biological characteristics of osteoblasts and Staphylococcus aureus.


Marzo, 2015 | DOI: 10.1016/j.actbio.2014.12.023

Nanotecnología en Superficies y Plasma

Laser Treatment of Ag@ZnO Nanorods as Long-Life-Span SERS Surfaces

Macias-Montero, M; Pelaez, RJ; Rico, VJ; Saghi, Z; Midgley, P; Afonso, CN; Gonzalez-Elipe, AR; Borras, A
ACS Applied Materials & Interfaces, 7 (2015) 2331-2339

UV nanosecond laser pulses have been used to produce a unique surface nanostructuration of Ag@ZnO supported nanorods (NRs). The NRs were fabricated by plasma enhanced chemical vapor deposition (PECVD) at low temperature applying a silver layer as promoter. The irradiation of these structures with single nanosecond pulses of an ArF laser produces the melting and reshaping of the end of the NRs that aggregate in the form of bundles terminated by melted ZnO spherical particles. Well-defined silver nanoparticles (NPs), formed by phase separation at the surface of these melted ZnO particles, give rise to a broad plasmonic response consistent with their anisotropic shape. Surface enhanced Raman scattering (SERS) in the as-prepared Ag@ZnO NRs arrays was proved by using a Rhodamine 6G (Rh6G) chromophore as standard analyte. The surface modifications induced by laser treatment improve the stability of this system as SERS substrate while preserving its activity.


Febrero, 2015 | DOI: 10.1021/am506622x

Materiales Nanoestructurados y Microestructura

STEM-EELS analysis reveals stable highdensity He in nanopores of amorphous silicon coatings deposited by magnetron sputtering

Schierholz, Roland; Lacroix, Bertrand; Godinho, Vanda; Caballero-Hernandez, Jaime; Duchamp, Martial; Fernandez, Asuncion
Nanotechnology, 26 (2015) 075703

A broad interest has been showed recently on the study of nanostructuring of thin films and surfaces obtained by low-energy He plasma treatments and He incorporation via magnetron sputtering. In this paper spatially resolved electron energy-loss spectroscopy in a scanning transmission electron microscope is used to locate and characterize the He state in nanoporous amorphous silicon coatings deposited by magnetron sputtering. A dedicated MATLAB program was developed to quantify the helium density inside individual pores based on the energy position shift or peak intensity of the He K-edge. A good agreement was observed between the high density (~35–60 at nm−3) and pressure (0.3–1.0 GPa) values obtained in nanoscale analysis and the values derived from macroscopic measurements (the composition obtained by proton backscattering spectroscopy coupled to the macroscopic porosity estimated from ellipsometry). This work provides new insights into these novel porous coatings, providing evidence of high-density He located inside the pores and validating the methodology applied here to characterize the formation of pores filled with the helium process gas during deposition. A similar stabilization of condensed He bubbles has been previously demonstrated by high-energy He ion implantation in metals and is newly demonstrated here using a widely employed methodology, magnetron sputtering, for achieving coatings with a high density of homogeneously distributed pores and He storage capacities as high as 21 at%.


Febrero, 2015 | DOI: 10.1088/0957-4484/26/7/075703

Materiales Nanoestructurados y Microestructura

Tribocorrosion behavior of TiBxCy/a-C nanocomposite coating in strong oxidant disinfectant solutions

Gracia-Escosa, E; Garcia, I; Sanchez-Lopez, JC; Abad, MD; Mariscal, A; Arenas, MA; de Damborenea, J; Conde, A
Surface & Coatings Technology, 263 (2015) 78-85

Corrosion and tribocorrosion studies of a TiBxCy/a-C coating deposited on AISI 316L steel have been performed in an aqueous solution of 026 vol.% acetic, 0.16 vol.% peracetic and 0.18 vol.% hydrogen peroxide (commercial product Oxonia I vol.%). The corrosion current density of the TiBxCy/a-C coating ranges on the same order as bare steel but with a significantly decreasing friction (0.1 vs. 0.6) and wear rate (similar to 10 times lower). The compact microstructure of the coating hinders the access of the aggressive electrolyte to the substrate, preventing the onset of the corrosion attack, while maintaining an excellent tribological behavior in strong oxidant solutions.


Febrero, 2015 | DOI: 10.1016/j.surfcoat.2014.12.047

Nanotecnología en Superficies y Plasma

Active vacuum brazing of CNT films to metal substrates for superior electron field emission performance

Longtin, R; Sanchez-Valencia, JR; Shorubalko, I; Furrer, R; Hack, E; Elsener, H; Groning, O; Greenwood, P; Rupesinghe, N; Teo, K; Leinenbach, C; Groning, P
Science and Technology of Advanced Materials, 16 (2015) 015005 (11 pp)

The joining of macroscopic films of vertically aligned multiwalled carbon nanotubes (CNTs) to titanium substrates is demonstrated by active vacuum brazing at 820 degrees C with a Ag-Cu-Ti alloy and at 880 degrees C with a Cu-Sn-Ti-Zr alloy. The brazing methodology was elaborated in order to enable the production of highly electrically and thermally conductive CNT/metal substrate contacts. The interfacial electrical resistances of the joints were measured to be as low as 0.35 Omega. The improved interfacial transport properties in the brazed films lead to superior electron fieldemission properties when compared to the as-grown films. An emission current of 150 mu A was drawn from the brazed nanotubes at an applied electric field of 0.6 V mu m(-1). The improvement in electron field-emission is mainly attributed to the reduction of the contact resistance between the nanotubes and the substrate. The joints have high re-melting temperatures up to the solidus temperatures of the alloys; far greater than what is achievable with standard solders, thus expanding the application potential of CNT films to high-current and high-power applications where substantial frictional or resistive heating is expected.


Febrero, 2015 | DOI: 10.1088/1468-6996/16/1/015005

Nanotecnología en Superficies y Plasma - Materiales y Procesos Catalíticos de Interés Ambiental y Energético

Sonogashira Cross-Coupling and Homocoupling on a Silver Surface: Chlorobenzene and Phenylacetylene on Ag(100)

Sanchez-Sanchez, C; Orozco, N; Holgado, JP; Beaumont, SK; Kyriakou, G; Watson, DJ; Gonzalez-Elipe, AR; Feria, L; Sanz, JF; Lambert, RM
Journal of the American Chemical Society, 137 (2015) 940-947

Scanning tunneling microscopy, temperature-programmed reaction, near-edge X-ray absorption fine structure spectroscopy, and density functional theory calculations were used to study the adsorption and reactions of phenylacetylene and chlorobenzene on Ag(100). In the absence of solvent molecules and additives, these molecules underwent homocoupling and Sonogashira cross-coupling in an unambiguously heterogeneous mode. Of particular interest is the use of silver, previously unexplored, and chlorobenzene—normally regarded as relatively inert in such reactions. Both molecules adopt an essentially flat-lying conformation for which the observed and calculated adsorption energies are in reasonable agreement. Their magnitudes indicate that in both cases adsorption is predominantly due to dispersion forces for which interaction nevertheless leads to chemical activation and reaction. Both adsorbates exhibited pronounced island formation, thought to limit chemical activity under the conditions used and posited to occur at island boundaries, as was indeed observed in the case of phenylacetylene. The implications of these findings for the development of practical catalytic systems are considered.


Enero, 2015 | DOI: 10.1021/ja5115584

Reactividad de Sólidos

Uniform, luminescent Eu: LuF3 nanoparticles

Becerro, AI; Gonzalez-Mancebo, D; Ocana, M
Journal of Nanoparticle Research, 17 (2015) 58

A simple procedure for the synthesis of orthorhombic, uniform, LuF3 particles with two different morphologies (rhombus- and cocoon-like) and nanometer and sub-micrometer size, respectively, is reported. The method consists in the aging, at 120 °C for 2 h, a solution containing [BMIM]BF4 ionic liquid (0.5 mL) and lutetium acetate (in the case of the rhombi) or lutetium nitrate (in the case of the cocoons) (0.02 M) in ethylene glycol (total volume 10 mL). This synthesis method was also adequate for the synthesis of Eu3+-doped LuF3 particles of both morphologies, whose luminescence properties were investigated in detail. The experimental observations reported herein suggest that these materials are suitable phosphors for optoelectronic as well as in vitro biotechnological applications.


Enero, 2015 | DOI: 10.1007/s11051-015-2874-z

Materiales Nanoestructurados y Microestructura

Biotribological behavior of Ag–ZrCxN1−x coatings against UHMWPE for joint prostheses devices

Calderon, SV; Sanchez-Lopez, JC; Cavaleiro, A; Carvalho, S
Journal of the Mechanical Behavior of Biomedical Materials, 41 (2015) 83-91

This study aims to evaluate the structural, mechanical and tribological properties of zirconium carbonitrides (ZrCxN1−x) coatings with embedded silver nanoparticles, produced with the intention of achieving a material with enhanced multi-functional properties, including mechanical strength, corrosion resistance, tribological performance and antibacterial behavior suitable for their use in joint prostheses. The coatings were deposited by direct current (DC) reactive magnetron sputtering onto 316 L stainless steel, changing the silver content from 0 to 20 at% by modifying the current density applied to the targets. Different nitrogen and acetylene gas fluxes were used as reactive gases. The coatings revealed different mixtures of crystalline ZrCxN1−x, silver nanoparticles and amorphous carbon phases. The hardness of the films was found to be mainly controlled by the ratio between the hard (ZrCxN1−x) and soft (Ag and amorphous carbon) phases in the films, fluctuating between 7.4 and 20.4 GPa. The coefficient of friction, measured against ultra-high molecular weight polyethylene (UHMWPE) in Hank’s balanced salt solution with 10 g L−1albumin, is governed by the surface roughness and hardness. The UHMWPE wear rates were in the same order of magnitude (between 1.4 and 2.0×10−6 mm3 N−1 m−1), justified by the effect of the protective layer of albumin formed during the tests. The small differences were due to the hydrophobic/hydrophilic character of the surface, as well as to the silver content.


Enero, 2015 | DOI: 10.1016/j.jmbbm.2014.09.028

Nanotecnología en Superficies y Plasma

Effect of magnesium and titanium on the cathodic behaviour of aluminium in nitric acid

Garcia-Garcia, FJ, Chiu, TY, Skeldon, P, Thompson, GE
Surface and Interface Analysis, 47 (2015) 30-36

Cathodic polarization of aluminium and Al-0.18wt.%Mg and Al-0.08wt.% Ti alloys in 0.24moldm(-3) nitric acid solution at 38 degrees C has been employed to assist understanding of the roles of alloying elements in electrograining. The findings indicate that additions of magnesium and titanium to aluminium accelerate the corrosion of the substrate under the alkalization caused by the cathodic reactions. The accelerated dissolution and the consequent formation of hydrated alumina result in a decreased net cathodic current density in potentiostatic and potentiodynamic polarization conditions relative to the behaviour of aluminium. 


Enero, 2015 | DOI: 10.1002/sia.5640



2014


Nanotecnología en Superficies y Plasma

Transmission electron microscopy of unstained hybrid Au nanoparticles capped with PPAA (plasma-poly-allylamine): Structure and electron irradiation effects

Gontard, LC; Fernandez, A; Dunin-Borkowski, RE; Kasama, T; Lozano-Perez, S; Lucas, S
Micron, 67 (2014) 1-9

Hybrid (organic shell–inorganic core) nanoparticles have important applications in nanomedicine. Although the inorganic components of hybrid nanoparticles can be characterized readily using conventional transmission electron microscopy (TEM) techniques, the structural and chemical arrangement of the organic molecular components remains largely unknown. Here, we apply TEM to the physico-chemical characterization of Au nanoparticles that are coated with plasma-polymerized-allylamine, an organic compound with the formula C3H5NH2. We discuss the use of energy-filtered TEM in the low-energy-loss range as a contrast enhancement mechanism for imaging the organic shells of such particles. We also study electron-beam-induced crystallization and amorphization of the shells and the formation of graphitic-like layers that contain both C and N. The resistance of the samples to irradiation by high-energy electrons, which is relevant for optical tuning and for understanding the degree to which such hybrid nanostructures are stable in the presence of biomedical radiation, is also discussed.


Diciembre, 2014 | DOI: 10.1016/j.micron.2014.06.004

Nanotecnología en Superficies y Plasma

LMM Auger primary excitation spectra of copper

Pauly, N; Tougaard, S; Yubero, F
Surface Science, 630 (2014) 294-299

The shape and intensity of measured Auger peaks are strongly affected by extrinsic excitations due to electron transport out of the surface and to intrinsic excitations induced by the sudden creation of the two static core holes. Following a method developed for XPS in a previous work [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17], we have calculated the effective energy-differential inelastic electron scattering cross-sections, including the effects of the surface and of the two core holes, within the dielectric response theory by means of the QUEELS-XPS software (QUantitative analysis of Electron Energy Losses at Surfaces for XPS). The Auger spectra are then modeled by convoluting this energy loss cross section with the primary excitation spectrum that accounts for all effects which are part of the initial Auger process, i.e. L–S coupling and vacancy satellite effects. The shape of this primary excitation spectrum is fitted to get close agreement between the theoretical and the experimental spectra obtained from X-ray excited Auger electron spectroscopy (XAES). We have performed these calculations of XAES spectra for various LMM Auger transitions of pure Cu (L3M45M45, L3M23M45, L3M23M23 and L2M45M45 transitions). We compare the resulting primary excitation spectra with theoretical results published in the literature and obtain reasonable quantitative agreement. In particular, we extract from experimental spectra quantitative intensities due to Coster–Kronig, shake-off and shake-up processes relative to the intensity from the “normal” Auger process.


Diciembre, 2014 | DOI: 10.1016/j.susc.2014.08.029

Nanotecnología en Superficies y Plasma

Quinone-Rich Poly(dopamine) Magnetic Nanoparticles for Biosensor Applications

Martin, M; Orive, AG; Lorenzo-Luis, P; Creus, AH; Gonzalez-Mora, JL; Salazar, P
ChemPhysChem, 15 (2014) 3742-3752

Novel core-shell quinone-rich poly(dopamine)–magnetic nanoparticles (MNPs) were prepared by using an in situ polymerization method. Catechol groups were oxidized to quinone by using a thermal treatment. MNPs were characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, magnetic force microscopy, UV/Vis, Fourier-transform infrared spectroscopy, and electrochemical techniques. The hybrid nanomaterial showed an average core diameter of 17 nm and a polymer-film thickness of 2 nm. The core-shell nanoparticles showed high reactivity and were used as solid supports for the covalent immobilization of glucose oxidase (Gox) through Schiff base formation and Michael addition. The amount of Gox immobilized onto the nanoparticle surface was almost twice that of the nonoxidized film. The resulting biofunctionalized MNPs were used to construct an amperometric biosensor for glucose. The enzyme biosensor has a sensitivity of 8.7 mA m−1 cm−2, a low limit of detection (0.02 mm), and high stability for 45 days. Finally, the biosensor was used to determine glucose in blood samples and was checked against a commercial glucometer.


Diciembre, 2014 | DOI: 10.1002/cphc.201402417

Materiales Nanoestructurados y Microestructura

Chemistry, nanostructure and magnetic properties of Co-Ru-B-O nanoalloys

Arzac, GM; Rojas, TC; Gontard, LC; Chinchilla, LE; Otal, E; Crespo, P; Fernandez, A
RSC Advances, 4 (2014) 46576-46586

In our previous works, Co–B–O and Co–Ru–B–O ultrafine powders with variable Ru content (xRu) were studied as catalysts for hydrogen generation through sodium borohydride hydrolysis. These materials have shown a complex nanostructure in which small Co–Ru metallic nanoparticles are embedded in an amorphous matrix formed by Co–Ru–B–O based phases and B2O3. Catalytic activity was correlated to nanostructure, surface and bulk composition. However, some questions related to these materials remain unanswered and are studied in this work. Aspects such as: 3D morphology, metal nanoparticle size, chemical and electronic information on the nanoscale (composition and oxidation states), and the study of the formation or not of a CoxRu1−x alloy or solid solution are investigated and discussed using XAS (X-ray Absorption Spectroscopy) and Scanning Transmission Electron Microscopy (STEM) techniques. Also magnetic behavior of the series is studied for the first time and the structure–performance relationships discussed. All Co-containing samples exhibited ferromagnetic behavior up to room temperature while the Ru–B–O sample is diamagnetic. For the xRu = 0.13 sample, an enhancement in the Hc (coercitive field) and Ms (saturation magnetization) is produced with respect to the monometallic Co–B–O material. However this effect is not observed for samples with higher Ru content. The presence of the CoxB-rich (cobalt boride) amorphous ferromagnetic matrix, very small metal nanoparticles (Co and CoxRu(1−x)) embedded in the matrix, and the antiferromagnetic CoO phase (for the higher Ru content sample, xRu = 0.7), explain the magnetic behavior of the series.