First-principles analysis to assess the solar water splitting and hydrogen storage capabilities of Cs2XGaH6 (X= Al, Na)

• Published in: International journal of hydrogen energy Vol. 83; pp. 124 - 132
• Main Authors: Murtaza, Hudabia, Ain, Quratul, Munir, Junaid, Ghaithan, Hamid M., Ahmed, Abdullah Ahmed Ali, Qaid, Saif M.H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 19-09-2024
• Subjects: Double perovskites; Hydrogen storage; Photocatalytic properties; Wien2K; Wien2K; Hydrogen storage; Photocatalytic properties; Double perovskites
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.07.213

Hydrogen storage has gained popularity recently due to its advantages as an energy source. Research on hydrogen storage applications primarily focuses on evaluating the ability of newly introduced compounds to store hydrogen. We have analyzed the physical characteristics of Cesium-based double perovskites Cs2XGaH6 (X = Al, Na) using the first-principles calculations incorporated in the Wien2K code. Exchange correlation is treated through two approximations, such as PBE-GGA, to compute the structural and mechanical traits of Cs2XGaH6 (X = Al, Na), and mBJ approximation to compute the optoelectronic and transport characteristics. The mechanical stability and brittleness of Cs2XGaH6 (X = Al, Na) compounds are revealed by the examination of the elastic stiffness constants. The thermodynamic and mechanical stabilities for double perovskites are assessed in detail. Electronic properties revealed indirect bandgap of 1.89 eV and 3.08 eV for Cs2AlGaH6 and Cs2NaGaH6, respectively. The optical traits are evaluated using the Kramer-Kroing complex equation. Several optical characteristics for Cs2XGaH6 (X = Al, Na) have been have been examined and calculated. In the ultraviolet UV spectrum, absorption spectra reveal a rise in the redshift. For hydrogen storage, Cs2XGaH6 (X = Al, Na) are attractive contenders due to their low energy losses at maximum absorption and highest static refractive index values. The gravimetric hydrogen storage capacity has been achieved up to 1.62 wt% for Cs2AlGaH6 and 1.64 wt% for Cs2NaGaH6. Moreover, the Cs2AlGaH6 is found to be effective for hydrogen reduction, while Cs2NaGaH6 is has better performance for oxygen reduction. In conclusion, this study provides evidence that Cs2XGaH6 (X = Al, Na) can be used as a viable solution for efficient hydrogen storage and photocatalytic activities.
•First-principles calculations have been performed to investigate the photocatalytic and hydrogen storage capacity of Cs2XGaH6 (X = Al, Na).•The optimization cures, negative formation energy and tolerance factor show the stability of the studied compounds.•For hydrogen storage, Cs2XGaH6 (X = Al, Na) are attractive contenders due to their low energy losses at maximum absorption.•Photocatalytic properties show the excellent response of Cs2XGaH6 (X = Al, Na) for solar hydrogen synthesis.