resumo
This study demonstrates how zirconia additive transforms to zirconium hydride and substantially lowers the dehydrogenation temperature of magnesium hydride. We prepared MgH2+xZrO(2) (x = 0.125 and 0.5) powder samples reacted for 15 min, 1 h, 5 h, 10 h, 15 h, 20 h and 25 h, and monitored the phase changes at each stage of the reaction. Differential scanning calorimetry (DSC) study provides the first crucial evidence regarding the chemical transformation of zirconia. Subsequently, detailed additional sample testing by X-ray diffraction (XRD), energy dispersive x-ray spectroscopy and confocal Raman microscopy provide strong supports that low temperature dehydrogenation of magnesium hydride is a result of formation of an active in situ product (zirconium hydride). This observation is validated by the negative Gibbs free energy values obtained for the formation of zirconium hydride over a broad working temperature range of 0-600 degrees C. Scanning electron microscopy (SEM) results prove the high dispersion of tiny nanoparticles all across the surface after the chemical interaction between MgH2 and ZrO2 and atomic force microscopy (AFM) study further proves that objects with grain sizes of similar to 10 nm are abundant throughout the scanned surfaces. These observations reiterate that better metal oxide additives interact with MgH2 and results to the evolution of highly active insitu nanocatalysts. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
palavras-chave
SORPTION KINETICS; DEHYDROGENATION KINETICS; ROOM-TEMPERATURE; METAL-OXIDES; MGH2; NANOPARTICLES; IMPROVEMENT; COMPOSITE; NB2O5; SIZE
categoria
Chemistry; Electrochemistry; Energy & Fuels
autores
Pukazhselvan, D; Silva, DAR; Sandhya, KS; Fateixa, S; Shaula, A; Nogueira, H; Bdikin, I; Fagg, DP
nossos autores
Helena Isabel Seguro Nogueira
Professor Auxiliar com Agregação
Sara Fateixa
Investigador Júnioragradecimentos
This work is supported by national funds (OE), through the FCT -Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23 of the Decree Law 57/2016, of August 29, POCI-01-0247-FEDER-039926, POCI-01-0145-FEDER-032241, UIDB/00481/2020 and UIDP/00481/2020, FCT, and PTDC/CTM-CTM/32241/ 2017 and by the Centro Portugal Regional Operational Programme Centro 2020, through the European Regional Development Fund (ERDF), in the scope of the project CENTRO-01-0145-FEDER-022083. D.P (Pukazh) acknowledges Fundacao para a Ciencia e a Tecnologia, FCT-Portugal for the financial support with the reference, CEECIND/04158/2017.