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2022


Characterization of Re-Mo/ZSM-5 catalysts: How Re improves the performance of Mo in the methane dehydroaromatization reaction


Lopez-Martin, A; Sini, MF; Cutrufello, MG; Caballero, A; Colon, G
Applied Catalysis B-Environmental, 304 (2022) 120960
Materiales y Procesos Catalíticos de Interés Ambiental y Energético

ABSTRACT ▼

In this study, the promoting effect of rhenium addition as a co-dopant on Mo/ZSM-5 catalysts system has been analysed. Hence, bimetallic (Re-Mo/ZSM-5) catalysts have been synthesized using a sequential impregnation methodology. The catalytic performance for direct aromatization of methane reaction has been determined and correlated with their physical and chemical state combining multiple characterization techniques. An important synergy between Mo and Re, affected by the sequential impregnation, has been observed. Thus, Re1-Mo4/ZSM-5 in which Re has been incorporated first shows notably higher aromatic yields and stability against deactivation. Characterization results suggest that catalytic enhancement is due to the important effect of Re presence in close interaction with Mo. Improved evolution of ethane through C-C coupling would be correlated to this catalytic performance. As we discuss, Mo nature and location in the bimetallic systems are strongly conditioned by Re and the impregnation sequence and favours such intermediate step.


Mayo, 2022 | DOI: 10.1016/j.apcatb.2021.120960

Insights into the physicochemical properties of Sugar Scum as a sustainable biosorbent derived from sugar refinery waste for efficient cationic dye removal


F. Atmani, M.M. Kaci, N. Yeddou-Mezenner, A. Soukeur, I. Akkari, J.A. Navío
Biomass Conversion and Biorefinery (2022)
Fotocatálisis Heterogénea: Aplicaciones

ABSTRACT ▼

The objective of this study was to determine the ability of sugar scum (SS), an industrial waste, as a novel biosorbent for the removal of Basic Blue 41 (BB 41) from aqueous solutions. The biosorbent was characterized by SEM/EDS, BET, FTIR, and pHpzc measurements, respectively. To reach a maximum adsorption capacity of 26.45 mg.g–1, impacting operational factors such as pH, biosorbent dose, contact duration, starting dye concentration, and temperature were adjusted, when the removal efficiency reached 84% during 60 min at pH 10, 1.5 g.L–1 of biosorbent and Co = 10 mg.L–1. The experimental data were modeled by various isotherm models, whereas the best fit was found for Freundlich with a high correlation coefficient (R2 = 0.991). Other kinetic models including pseudo-first, pseudo-second order, and intra-particle diffusion models were tested to fit the kinetic data. The biosorption of BB 41 onto SS was spontaneous (∆G° < 0) and exothermic (∆H° < 0), while the biosoprtion mechanism of BB41 over SS was proposed with repeated reuse showing that SS could be regenerated after four successive runs. Furthermore, this study revealed that sugar scum is an underutilized bioresource in Algeria, with the potential to provide low-cost environmental removal of additional contaminants in the wastewater treatment domain.


Abril, 2022 | DOI: 10.1007/s13399-022-02646-3

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
Materiales para Bioingeniería y Regeneración Tisular

ABSTRACT ▼

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

Composition and technological features of ceramics manufactured by Benito de Valladares in the seventeenth century from the Alcazar Palace in Seville, Spain


Pérez-Rodríguez, J.L.; Robador, M.D.; Duran, A.
European Physical Journal Plus, 137 (2022) 469

ABSTRACT ▼

The walls of the Alcazar Palace in Seville have been covered with ceramic tiles of different styles that were manufactured with different techniques. Several studies have been carried out on these ceramics, but no interest has been paid to the tiles manufactured by the workshop of the Valladares family, one of the most productive ceramic workshops in Triana (Seville). In this work, tiles that were made in the Valladares workshop are studied for the first time. The tiles from the Cenador del Leon built in 1645-1646 were chosen. The experimental studies suggest that the ceramic body was manufactured with silico-calcareous clay. This raw material was heated to a temperature of ca. 900 degrees C. A nondestructive and on-site analytical procedure was applied first. Microsamples were also taken and studied through microanalytical techniques. The maiolica style was used by Benito de Valladares for tile manufacture. The glaze phases were constituted by two layers. The pigments and doping elements used to obtain different colors were characterized. Valladares' work is considered as a continuation of Augusta's work; therefore, a comparison between both ceramists has been realized to better understand the ceramics production in southern Spain during the sixteenth to seventeenth centuries.


Abril, 2022 | DOI: 10.1140/epjp/s13360-022-02669-9

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
Nanotecnología en Superficies y Plasma

ABSTRACT ▼

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

Ageing-resistant zirconia/graphene-based nanostructures composites for use as biomaterials


Morales-Rodriguez, A; Gonzalez-Orellana, C; Perez-Garcia, AA; Lopez-Pernia, C; Munoz-Ferreiro, C; Poyato, R; Gallardo-Lopez, A
Journal of the European Ceramic Society, 42 (2022) 1784-1795
Reactividad de Sólidos

ABSTRACT ▼

This work explores the incorporation of graphene-based two-dimensional nanostructures as moisture barriers to delay hydrothermal ageing of yttria-stabilized zirconia and strengthen its use in biomedical applications. Two sets of highly dense zirconia composites incorporating multilayered graphene with very different lateral dimensions, few layer graphene and exfoliated graphene nanoplatelets, were prepared. The effect of the addition of graphene nanostructures on zirconia ageing was investigated by conducting accelerated hydrothermal degradation experiments in an autoclave. An improved resistance to low-temperature degradation and a high tolerance to damage were achieved in the composites compared to those of monolithic zirconia. The incorporation of 1 vol% multilayered graphene was very effective in restricting the hydrothermal degradation. In particular, the composite incorporating exfoliated graphene nanosheets exhibited outstanding resistance to ageing because of their fine dispersion throughout the matrix, which effectively seemed to restrict grain growth and slow the propagation of the transformation front to the ceramic bulk.


Abril, 2022 | DOI: 10.1016/j.jeurceramsoc.2021.11.060

H-2 Photoproduction Efficiency: Implications of the Reaction Mechanism as a Function of the Methanol/Water Mixture


Barba-Nieto, I; Colon, G; Kubacka, A; Fernandez-Garcia, M
Catalysts, 12 (2022) 402
Materiales y Procesos Catalíticos de Interés Ambiental y Energético

ABSTRACT ▼

The influence of the reaction pathway of the sacrificial molecule oxidation to generate hydrogen is here investigated for lean and rich methanol reaction mixtures. Pt-TiO2 powders promoted or not with tin sulfide were used as catalysts. With the help of in situ infrared experiments under reaction conditions, methanol evolution was shown to take place by hole-related oxidation steps, with alkoxy and carbon-centered species as key radical species. The study analyzed quantitatively the fate and chemical use of the photons absorbed by the solids with the help of the quantum efficiency and the useful fraction of photons observables. Within this framework, the role of the sulfide component to promote photoactivity is interpreted, braiding chemical and photonic information.


Abril, 2022 | DOI: 10.3390/catal12040402

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
Nanotecnología en Superficies y Plasma

ABSTRACT ▼

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

Z-scheme WO3/PANI heterojunctions with enhanced photocatalytic activity under visible light: A depth experimental and DFT studies


Y. Naciri; A.Hsini; A.Bouziani; K.Tanji; B.El Ibrahimi; M.N.Ghazza; B. Bakiz; A.Albourine; A.Benlhachemi; J.A. Navío
Chemosphere, 292 (2022) 133468
Fotocatálisis Heterogénea: Aplicaciones

ABSTRACT ▼

A WO3@PANI heterojunction photocatalyst with a various mass ratio of polyaniline to WO3 was obtained via the in situ oxidative deposition polymerization of aniline monomer in the presence of WO3 powder. The characterization of WO3@PANI composites was carried via X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). The photocatalytic efficiency of WO3@PANI photocatalysts was assessed by following the decomposition of the Rhodamine B (RhB) dye under visible light irradiation (λ >420 nm). The results evidenced the high efficiency of the WO3@PANI (0.5 wt %) nanocomposite in the photocatalytic degradation of RhB (90% within 120 min) under visible light irradiation 3.6 times compared to pure WO3. The synergistic effect between PANI and WO3 is the reason for the increased photogenerated carrier separation. The superior photocatalytic performance of the WO3@PANI catalyst was ascribed to the increased visible light in the visible range and the efficient charge carrier separation. Furthermore, the Density Functional Theory study (DFT) of WO3@PANI was performed at the molecular level, to find its internal nature for the tuning of photocatalytic efficiency. The DFT results indicated that the chemical bonds connected the solid-solid contact interfaces between WO3 and PANI. Finally, a plausible photocatalytic mechanism of WO3@PANI (0.5 wt %) performance under visible light illumination is suggested to guide additional photocatalytic activity development.


Abril, 2022 | DOI: 10.1016/j.chemosphere.2021.133468

Highly uniform Y3Al2Ga3O12-based nanophosphors for persistent luminescence bioimaging in the visible and NIR regions


Arroyo, E; Herrero, BT; De la Fuente, JM; Ocaña, M; Becerro, AI
Inorganic Chemistry Frontiers
Reactividad de Sólidos

ABSTRACT ▼

In the last few years, persistent phosphors with a garnet crystal structure have attracted a great deal of interest for a plethora of applications ranging from bioimaging to anti-counterfeiting technologies. However, the development of synthesis methods to fabricate uniform garnet-based micro and nanoparticles, that are needed for such applications, is not mature at all. This study reports the synthesis of highly uniform yttrium aluminum gallium garnet nanospheres. The method is based on homogeneous precipitation in a polyol medium followed by silica coating and calcination. The nanoparticles resulting after silica removal were also uniform and were easily functionalized with polyacrylic acid. The colloidal stability of the latter in physiological media and their biocompatibility were analyzed. The luminescence of the particles, doped with Ce3+, Cr3+, and Nd3+, was studied by recording emission and excitation spectra and persistent luminescence decay curves. Due to their uniform morphology, high colloidal stability, absence of toxicity, and persistent emission in the visible and near-infrared regions, the reported nanospheres show great potential as persistent luminescent bioimaging probes. In addition, the synthesis method paves the way for future use of this persistent material in other applications that require the phosphor to be in the form of highly uniform nanoparticles.


Abril, 2022 | DOI: 10.1039/d2qi00480a

Insights into the structural and physicochemical properties of Zn-Bi-O composites for efficient photodegradation of caffeic acid, rhodamine B and methyl orange


F.Puga; J.A.Navío; J.M.Córdoba; F.Romero-Sarria; M.C.Hidalgo
Applied Surface Science, 581 (2022) 152351
Fotocatálisis Heterogénea: Aplicaciones

ABSTRACT ▼

Different Zn-Bi-O composites were synthesized following the starting chemical molar composition of ZnBi2O4 spinels by a sol–gel method, (ZnBiO)-SG, and its subsequent hydrothermal treatment, (ZnBiO)-HT. The acquired X-ray diffractograms after sequential thermal treatments at a programmed rate indicate that both precursors evolved, after calcination at 500 °C, to materials (ZnBiO) with different stoichiometry. The use of different characterization techniques (both FT-IR and TEM), allowed us to establish that, with the sol–gel process a mixed ZnO/Bi2O3 oxide is generated, while after hydrothermal process a ternary Zn-Bi-O oxide is formed, with small amounts of residual ZnO. The photocatalytic properties of the synthesized samples were evaluated using Caffeic acid, Rhodamine B and Methyl Orange as model substrates. It can be concluded that both catalysts showed excellent photocatalytic activity for the degradation of trans-caffeic acid under both UV and visible illumination. The leaching process (in particular of zinc), which is produced with the illumination time (in particular under UV illumination) in the presence of oxygen, raises the hypothesis of a foreseeable formation of complexes (photochemically stable or unstable) of caffeic acid with Zn2+ and Bi3+ ions. The plausible donor/acceptor interactions between the toxic molecules studied and the Zn2+ and Bi3+ ions, could condition the degradation processes, by means of a photoassisted process that would take place both, in the heterogeneous (photocatalytic) and homogeneous (photoassisted) phases. For the degradation processes of Rhodamine B and Methyl Orange, additional experimental conditions are studied that significantly improved their photocatalytic degradation.


Abril, 2022 | DOI: 10.1016/j.apsusc.2021.152351

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
Nanotecnología en Superficies y Plasma

ABSTRACT ▼

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

Enhanced up-conversion photoluminescence in fluoride-oxyfluoride nanophosphor films by embedding gold nanoparticles


Ngo, TT; Lozano, G; Miguez, H
Materials Advances (2022)
Materiales Ópticos Multifuncionales

ABSTRACT ▼

Owing to their unique non-linear optical character, lanthanide-based up-converting materials are potentially interesting for a wide variety of fields ranging from biomedicine to light harvesting. However, their poor luminescent efficiency challenges the development of technological applications. In this context, localized surface plasmon resonances (LSPRs) have been demonstrated as a valuable strategy to improve light conversion. Herein, we utilize LSPR induced by gold nanoparticles (NPs) to enhance up-conversion photoluminescence (UCPL) in transparent, i.e. scattering-free, films made of nanophosphors formed by fluoride–oxyfluoride host matrix that feature high thermal stability. Transparency allows excitation by an external source without extinction losses caused by unwanted diffuse reflection. We provide a simple method to embed gold NPs in films made of YF/YOF:Yb3+,Er3+ UC nanophosphors, via preparation of a viscous paste composed of both UC nanophosphors and colloidal gold NPs, reducing complexity in sample fabrication. The dimensions of gold NPs are such that their associated LSPR matches spectrally with the green emission band of the Er3+ doped nanophosphors. In order to demonstrate the benefits of plasmonic nanoparticles for UCPL in nanophosphor films, we provide a careful analysis of the structural properties of the composite thin films along with precise characterization of the impact of the gold NPs on the photophysical properties of UC nanophosphors.


Abril, 2022 | DOI: 10.1039/D2MA00068G

Structural analysis of mixed alpha- and beta-amyrin samples


Gomez-Pulido, LDM; Gonzalez-Cano, RC; Benitez, JJ; Dominguez, E; Heredia, A
Royal Society Open Science, 9 (2022) 211787
Materiales de Diseño para la Energía y Medioambiente

ABSTRACT ▼

Little is known about the structure and molecular arrangement of alpha- and beta-amyrin, a class of triterpenoids found within the cuticle of higher plants. Blends of both amyrin isomers with different ratios have been studied taking into consideration a combined methodology of density functional theory (DFT) calculations with experimental data from scanning electron microscopy, differential scanning calorimetry and Raman vibrational spectroscopy. Results indicate that trigonal trimeric aggregations of isomer mixtures are more stable, especially in the 1 : 2 (alpha : beta) ratio. A combination of Raman spectroscopy and DFT calculations has allowed to develop an equation to determine the amount of beta-amyrin in a mixed sample.


Abril, 2022 | DOI: 10.1098/rsos.211787

Insight into the role of temperature, time and pH in the effective zirconium retention using clay minerals


Pavon, E; Alba, MD
Journal of Environmental Chemical Engineering, 308 (2022) 114635
Materiales y Procesos Catalíticos de Interés Ambiental y Energético

ABSTRACT ▼

The use of zirconium in chemical industries generates a potential risk of Zr contamination in the environment, with particular concern for the decommissioning of uranium-graphite reactors. Among the natural adsorbents employed for the treatment of nuclear waste, clay minerals showed a very high affinity adsorption for radionuclides, but the influence of the chemical composition, pressure, temperature and time reaction have not yet been analysed on deep. Thus, the objective of this research is to explore several experimental conditions for an actual prediction of the behaviour of zirconium immobilization by clay minerals. The results have shown that factors such as zirconium cation nature (Zr4+ or ZrO2+), temperature, time and pH influence the extent of zirconium immobilization by clay minerals and the zirconium phases generated. At moderate conditions, zirconium tectosilicates are formed and evolve to zircon at high temperature and a longer time reaction.


Abril, 2022 | DOI: 10.1016/j.jenvman.2022.114635

Fast photodegradation of rhodamine B and caffeine using ZnO-hydroxyapatite composites under UV-light illumination


KarimTanji, J.A.Navio, Abdellah Chaqroune, Jamal Naja, F.Puga, M.C.Hidalgo, AbdelhakKherbeche
Catalysis Today, 388 (2022) 176-186
Fotocatálisis Heterogénea: Aplicaciones

ABSTRACT ▼

Zinc oxide-hydroxyapatite composites were prepared using wet impregnation method. Firstly, a natural phosphate ore rich in silica and calcium phosphate was sieved to separate silica phase from phosphate phase. Then, through a chemical precipitation method, a pure hydroxyapatite (HAP) was obtained, which was used as a support for ZnO immobilization and applied for the photodegradation of two toxic contaminants: a transparent molecule (caffeine) and dye molecule (rhodamine B). During the present work two weight ratio percentages of zinc oxide were used: 25 wt.% and 50 wt.% of ZnO relative to HAP. The samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), X-ray Fluorescence (XRF), BET surface area (SBET), Scanning Electron Microscopy (SEM-EDS) and by Transmission Electron Microscopy (TEM-STEM). The immobilization of ZnO on HAP surface followed by thermal treatment at 400 °C for 2 h to get a homogenous dispersion of ZnO on the hydroxyapatite support. At high ZnO impregnation percentage, photodegradation performances of ZnO-HAP under UV illumination were fast and superior than the ZnO photocatalyst alone. The results showed that due to the presence of HAP, the conversion of both molecules became faster and greater, since it promotes the synergic phenomena of adsorption and photocatalysis. The toxicity of the treated substrate solutions obtained in the corn kernels germination test indicated a low toxicity after the photodegradation processes, probably due to a high mineralization degree.


Abril, 2022 | DOI: 10.1016/j.cattod.2020.07.044

Strength and thermal shock resistance of fiber-bonded Si-Al-C-O and Si-Ti-C-O ceramics


Vera, MC; Martinez-Fernandez, J; Singh, M; Ramirez-Rico, J
International Journal of Applied Ceramic Technology, 19 (2022) 1126-1135
Materiales de Diseño para la Energía y Medioambiente

ABSTRACT ▼

Silicon carbide-based fiber-bonded ceramics, obtained from hot pressing of woven silicon carbide fibers, are a cost-effective alternative to ceramic-matrix composites due to their ease of fabrication, involving few processing steps, and competitive thermomechanical properties. In this work, we studied the high-temperature strength and thermal shock resistance of Si-Al-C-O and Si-Ti-C-O fiber-bonded SiC ceramics obtained from hot pressing of two types of ceramic fibers, by mechanical testing in four-point bending. The bending strength of Si-Al-C-O-based fiber-bonded ceramics at room temperature is similar to 250-260 MPa and remains constant with temperature, while the bending strength of Si-Ti-C-O increases slightly from the initial 220 to similar to 250 MPa for the highest temperature. Both materials retain up to 90% of their room temperature strength after thermal shocks of 1400 degrees C and show no reduction in elastic moduli. After thermal shock, failure mode is the same as in the case of as-received materials.


Marzo, 2022 | DOI: 10.1111/ijac.13928

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
Nanotecnología en Superficies y Plasma

ABSTRACT ▼

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

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
Nanotecnología en Superficies y Plasma

ABSTRACT ▼

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

Analysis of Dry Reforming as direct route for gas phase CO2 conversion. The past, the present and future of catalytic DRM technologies


le Sache, E; Reina, TR
Progress in Energy and Combustion Science, 89 (2022) 100970
Química de Superficies y Catálisis

ABSTRACT ▼

Transition to low carbon societies requires advanced catalysis and reaction engineering to pursue green routes for fuels and chemicals production as well as CO2 conversion. This comprehensive review provides a fresh perspective on the dry reforming of methane reaction (DRM) which constitutes a straightforward approach for effective CO2 conversion to added value syngas. The bottleneck for the implementation of this process at industrial scale is the development of highly active and robust heterogeneous catalysts able to overcome the CO2 activation barrier and deliver sufficient amount of the upgrading products at the desired operation conditions. Also, its high energy demand due to the endothermic nature of the reaction imposes extra difficulties. This review critically discusses the recent progresses on catalysts design ranging from traditional metal-supported catalysts to advanced structured and nanostructured systems with promising performance. The main advantages and culprits of the different catalytic systems are introduced aiming to inspire the catalysis community to further refine these formulations towards the development of "supercatalysts" for DRM. Besides the design of increasingly complex catalyst morphologies as well as other promising alternatives aiming at reducing the energy consumption of the process or tackle deactivation through reactor design are introduced.


Marzo, 2022 | DOI: 10.1016/j.pecs.2021.100970

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