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Scientific Papers in SCI



2023


Materiales Ópticos Multifuncionales

Enhancement of upconversion photoluminescence in phosphor nanoparticle thin films using metallic nanoantennas fabricated by colloidal lithography

Ngo, TT; Viaña, JM; Romero, M; Calvo, ME; Lozano, G; Miguez, H
Materials Advances, 4 (2023) 6381-6388

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Lanthanide-doped upconversion nanoparticles (UCNPs), as multifunctional light sources, are finding utility in diverse applications ranging from biotechnology to light harvesting. However, the main challenge in realizing their full potential lies in achieving bright and efficient photon upconversion (UC). In this study, we present a novel approach to fabricate an array of gold nanoantennas arranged in a hexagonal lattice using a simple and inexpensive colloidal lithography technique, and demonstrate a significant enhancement of UC photoluminescence (UCPL) by up to 35-fold through plasmon-enhanced photoexcitation and emission. To elucidate the underlying physical mechanisms responsible for the observed UCPL enhancement, we provide a comprehensive theoretical and experimental characterization, including a detailed photophysical description and numerical simulations of the spatial electric field distribution. Our results shed light on the fundamental principles governing the enhanced UCNPs and pave the way for their potential applications in photonic devices.


November, 2023 | DOI: 10.1039/D3MA00775H

Fotocatálisis Heterogénea: Aplicaciones

Bismuth ferrite as innovative and efficient photocatalyst for the oxidation of As(III) to As(V) under visible light

Chianese, L; Murcia, JJ; Hidalgo, MC; Vaiano, V; Iervolino, G
Materials Science in Semiconductor Processing, 167 (2023) 107801

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The presence of As in drinking water is a problem felt all over the world. In particular, arsenic is present in +3 (As(III)) and +5 (As(V)) oxidation states. However, As(III) is the most toxic and difficult to remove with conventional adsorption processes. A pre-oxidation process is therefore necessary. In this work, we report, for the first time, the use of BiFeO3 as a visible-light active photocatalyst for the complete and fast oxidation of As(III) to As(V) in water. In particular, the influence of annealing temperature for BiFeO3 preparation was studied and the prepared photocatalysts were characterized through XRD, N2 adsorption at −196°C, TEM, XPS, Raman and UV–Vis DRS spectroscopy. The best photocatalytic activity was achieved with BiFeO3 calcined at 550°C. The influence of catalyst dosage and the role of the main oxidizing species was evaluated, evidencing the key role of h+ in the photooxidation reaction of As(III) to As(V). Moreover, the efficiency of the photocatalyst was also evaluated in the case of drinking water contaminated by arsenic. The results demonstrated that, despite the presence of dissolved salts in the drinking water, the photocatalyst maintained its activity. The results obtained in this work prove that BiFeO3 calcined at 550°C evidenced photocatalytic performances better than different photocatalyst formulations studied for the photooxidation of As(III) to As(V) under visible light.


November, 2023 | DOI: 10.1016/j.mssp.2023.107801

Química de Superficies y Catálisis

Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift

Gul Hameed, Ali Goksu, Loukia-Pantzechroula Merkouri, Anna Penkova, Tomas Ramirez Reina, Sergio Carrasco Ruiz, Melis Seher Duyar
Journal of CO2 Utilization, 77 (2023) 102606

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Nickel phosphide catalysts show a high level of selectivity for the reverse water-gas shift (RWGS) reaction, inhibiting the competing methanation reaction. This work investigates the extent to which suppression of methanation can be controlled by phosphidation and tests the stability of phosphide phases over 24-hour time on stream. Herein the synthesis of different phosphide crystal structures by varying Ni/P atomic ratios (from 0.5 to 2.4) is shown to affect the selectivity to CO over CH4 in a significant way. We also show that the activity of these catalysts can be fine-tuned by the synthesis Ni/P ratio and identify suitable catalysts for low temperature RWGS process. Ni12P5-SiO2 showed 80–100% selectivity over the full temperature range (i.e., 300–800 °C) tested, reaching 73% CO2 conversion at 800 °C. Ni2P-SiO2 exhibited CO selectivity of 93–100% over a full temperature range, and 70% CO2 conversion at 800 °C. The highest CO2 conversions for Ni12P5-SiO2 at all temperatures among all catalysts showed its promising nature for CO2 capture and utilisation. The methanation reaction was suppressed in addition to RWGS activity improvement through the formation of nickel phosphide phases, and the crystal structure was found to determine CO selectivity, with the following order Ni12P5 >Ni2P > Ni3P. Based on the activity of the studied catalysts, the catalysts were ranked in order of suitability for the RWGS reaction as follows: Ni12P5-SiO2 (Ni/P = 2.4) > Ni2P-SiO2 (Ni/P = 2) > NiP-SiO2 (Ni/P = 1) > NiP2-SiO2 (Ni/P = 0.5). Two catalysts with Ni/P atomic ratios; 2.4 and 2, were selected for stability testing. The catalyst with Ni/P ratio = 2.4 (i.e., Ni12P5-SiO2) was found to be more stable in terms of CO2 conversion and CO yield over the 24-hour duration at 550 °C. Using the phosphidation strategy to tune both selectivity and activity of Ni catalysts for RWGS, methanation as a competing reaction is shown to be no longer a critical issue in the RWGS process for catalysts with high Ni/P atomic ratios (2.4 and 2) even at lower temperatures (300–500 °C). This opens up potential low temperature RWGS opportunities, especially coupled to downstream or tandem lower temperature processes to produce liquid fuels.


November, 2023 | DOI: 10.1016/j.jcou.2023.102606

Reactividad de Sólidos

Integration of calcium looping and calcium hydroxide thermochemical systems for energy storage and power production in concentrating solar power plants

Carro, A; Chacartegui, R; Ortiz, C; Arcenegui-Troya, J; Perez-Maqueda, LA; Becerra, JA
Energy, 283 (2023) 128388

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Energy storage is a key factor in the development of renewables-based electrical power systems. In recent years, the thermochemical energy storage system based on calcium-looping has emerged as an alternative to molten salts for energy storage in high-temperature concentrated solar power plants. This technology still presents some challenges that could be solved by integrating the thermochemical energy storage system based on calcium hydroxide. This work studies a novel concentrated solar power system integrating calcium-looping and calcium hydroxide thermochemical energy storage systems. The results show that the combined use of hydration -dehydration cycles in the calcination-carbonation processes of the calcium looping for energy storage could partially solve the issue related to the multicyclic deactivation of calcium oxide. The improvement in the con-version of calcium oxide during carbonation is demonstrated experimentally when hydration-dehydration cycles are combined. Numerical simulations demonstrate the technical feasibility of the integrated process, with effi-ciencies ranging between 38-46%, improved with the increase in calcium oxide conversion in the carbonator, showing the potential of the proposed integration.


November, 2023 | DOI: 10.1016/j.energy.2023.128388

Química de Superficies y Catálisis

Mechanistic insights into methanol carbonylation to methyl acetate over an efficient organic template-free Cu-exchanged mordenite

Luque-Alvarez, LA; Gonzalez-Arias, J; Romero-Sarria, F; Reina, TR; Bobadilla, LF; Odriozola, JA
Catalysis Science & Technology

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Currently, acetic acid is produced via the carbonylation reaction of methanol with the main route entailing the use of homogeneous noble metal-based catalysts, which has certain limitations, including the use of polluting alkyl halide promoters and difficulty in catalyst recovery. To overcome these challenges, the exploration of alternative methods utilizing heterogeneous catalysts, particularly zeolites with copper as a redox center, has gained attention. Nonetheless, the conversion and selectivity obtained are sought after to compete against the homogeneous route. Therefore, a deeper understanding of the reaction and mechanism is needed to determine the weak points and overcome them. In this study, we propose the use of time-resolved operando DRIFTS-MS to study the methanol carbonylation reaction over a Cu–H-MOR catalyst. The study aimed to propose a reaction mechanism through an investigation of the behavior of the catalyst, including potential identification of the location of the copper redox center in the zeolite. The catalytic performance of the Cu–H-MOR catalyst was also evaluated, demonstrating its activity and stability in the methanol carbonylation reaction. The operando DRIFTS-MS results provide insights into the reaction mechanism and the involvement of the acid and redox centers in the process. Based on the findings, we propose a reaction mechanism for methanol carbonylation on Cu–H-MOR zeolite: (i) methanol dehydration, (ii) CO insertion into methoxide groups, (iii) reaction between dimethyl ether and acetyl groups, and (iv) hydrolysis of methyl acetate. Overall, we believe that this work contributes to a deeper understanding of the heterogeneous route for acetic acid production and offers potential avenues for optimizing the process.


November, 2023 | DOI: 10.1039/d3cy01271a

 

 

 

 

 

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