Artículos SCI
2023
2023
Materiales Ópticos Multifuncionales - Materiales Coloidales
Oxidation and coordination states assumed by transition metal dopants in an invert ultrabasic silicate glass
Zandona, A; Castaing, V; Shames, AI; Helsch, G; Deubener, J; Becerro, AI; Allix, M; Goldstein, AJournal of Non-Crystalline Solids, 603 (2023) 122094
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An ultrabasic invert silicate glass (46SiO2.11Na2O.21CaO.22BaO, optical basicity index equal to 0.71) was synthesized (O2 atmosphere) and used as host for various transition metal dopants. Optical absorption, emission and electron paramagnetic spectroscopies were used to characterize oxidation and coordination states. Some of the dopants displayed only their maximal oxidation state (Ti4+, V5+, Cr6+, Mo6+ and W6+). Others exhibited mixed valences: (i) Mn3+ was the dominant species, alongside Mn2+ and Mn5+; (ii) stable Fe3+ prevailed, although some Fe2+ was preliminarily suggested by the absorption spectrum; (iii) Co3+ probably accompanied the dominant Co2+ tetrahedral oxide complex; (iv) like in "conventional" silicate glasses, only Ni2+ was detected, though simultaneously located in tetrahedral and octahedral sites (somewhat distorted); (v) Cu+ was surprisingly identified alongside the expected 6-fold coordinated Cu2+. Drastic reduction of the oxygen content in the melting atmosphere led to conversion of Cr6+ to Cr3+, despite the extreme basicity of the host.
Marzo, 2023 | DOI: 10.1016/j.jnoncrysol.2022.122094
Química de Superficies y Catálisis
Functionalized Biochars as Supports for Ru/C Catalysts: Tunable and Efficient Materials for γ-Valerolactone Production
Bounoukta, CE; Megias-Sayago, C; Navarro, JC; Ammari, F; Ivanova, S; Centeno, MANanomaterials, 13 (2023) 1129
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/nanomaterials-13-01129-ag-550.png)
Cotton stalks-based biochars were prepared and used to synthetize Ru-supported catalysts for selective production of gamma-valerolactone from levulinic acid in aqueous media. Different biochars' pre-treatments (HNO3, ZnCl2, CO2 or a combination of them) were carried out to activate the final carbonaceous support. Nitric acid treatment resulted in microporous biochars with high surface area, whereas the chemical activation with ZnCl2 substantially increases the mesoporous surface. The combination of both treatments led to a support with exceptional textural properties allowing the preparation of Ru/C catalyst with 1422 m(2)/g surface area, 1210 m(2)/g of it being a mesoporous surface. The impact of the biochars' pre-treatments on the catalytic performance of Ru-based catalysts is fully discussed.
Marzo, 2023 | DOI: 10.3390/nano13061129
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, PPhysica Status Solidi A-Applications and Materials Science (2023) 2200765
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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
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Revealing the Impact of Different Iron-Based Precursors on the ‘Catalytic’ Graphitization for Synthesis of Anode Materials for Lithium Ion Batteries
Frankenstein, L; Glomb, P; Ramirez-Rico, J; Winter, M; Placke, T; Gomez-Martin, AChemelectrochem, 10 (2023) e202201073
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/celc202201073-toc-0001-m_0.png)
Low cost and environmentally friendly production of graphite anodes from naturally available biomass resources is of great importance to satisfy the increasing material demand for lithium ion batteries. Herein, graphitization of coffee ground was performed using four different iron-based activating additives, including iron (III) chloride, iron (III) nitrate, iron (III) oxide and pure iron, following either a wet or a dry mixing approach. The structural development regarding the type of activator used and the impact on the corresponding electrochemical performance are systematically investigated. A maximum degree of graphitization between 55 and 74 % (as determined by Raman spectroscopy) is attained using iron (III) chloride and iron powder, respectively. The graphitic anode material synthesized using iron powder reached a maximum reversible capacity of approximate to 320 mAh g(-1) at a rate of 0.1 C. This study provides significant insights into the impact of activators on the design of synthetic graphite from renewable sources.
Marzo, 2023 | DOI: 10.1002/celc.202201073
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, ANPJ 2D Materials and Applications, 7 (2023) 24
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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
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