resumo
In continuation with the results explored in our recent previous study (https://doi.org/10. 1016/j.apsusc.2021.150062), the current work sheds more light regarding the active in situ catalytic species in ceria additive loaded hydrogen storage system, MgH2. For this study, two samples, MgH2+0.167CeO(2) and MgH2+0.5CeO(2) were processed through mechanical milling (5 h/200 rpm) and tests were conducted at various stages of hydrogenation/dehy-drogenation cycles (cycles: 1, 5 and 10). Evidence for mild chemical interaction between MgH2 and CeO2 is observed at the time of mechanical milling, whereas strong redox type interaction is witnessed in the cycle tested samples. In-situ X ray diffraction study con-firms that the thermally activated interaction between MgH2 and CeO2 does not produce MgO. In situ Raman spectra provide crucial evidence that reduced cerium oxides exist at all stages of interactions in the MgH2/CeO2 hydrogen storage system. Detailed advanced electron microscopic observations concur well with the in-situ X ray diffraction and Raman spectroscopy studies. Although Gibbs free energy calculations reveal the possible existence of cerium hydrides, owing to the structural similarities between CeHx and CeOx phases, the chemical identity of the most abundant catalytic product remains debatable. Regarding the catalytic mechanism, suppression of MgO rock salt formation is identified to be a key step where the role of CeHx/CeOx interfaces gains more importance. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
palavras-chave
HYDROGEN STORAGE PROPERTIES; SORPTION IMPROVEMENT; ROOM-TEMPERATURE; RAMAN-SCATTERING; MGH2; NB2O5; CEO2; COMPOSITE; BEHAVIOR; OXIDE
categoria
Chemistry; Electrochemistry; Energy & Fuels
autores
Pukazhselvan, D; Caha, I; Jakka, SK; Graca, VCD; Holz, LIV; Soares, MJ; Kovalevsky, AV; Deepak, FL; Fagg, DP
nossos autores
Andrei Kavaleuski
Investigador principalProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This work is supported by national funds (OE), through the FCTeFundacao para a Ciencia e a Tecnologia, I.P., in the scopeof the framework contract foreseen in the numbers 4, 5 and 6of 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, UIDB/50011/2020, LA/P/0006/2020, PTDC/CTM-CTM/32241/2017, CASOLEM (028917) and by the CentroPortugal Regional Operational Programme Centro 2020,through the European Regional Development Fund, in thescope of the project CENTRO-01-0145-FEDER-022083. D. P(Pukazh) acknowledges FCT for the financial support with thereference, CEECIND/04158/2017