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

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 Cs 2 XGaH 6 (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 Cs 2 XGaH 6 (X = Al, Na), and mBJ approximation to compute the optoelectronic and transport characteristics. The mechanical stability and brittleness of Cs 2 XGaH 6 (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 Cs 2 AlGaH 6 and Cs 2 NaGaH 6 , respectively. The optical traits are evaluated using the Kramer-Kroing complex equation. Several optical characteristics for Cs 2 XGaH 6 (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, Cs 2 XGaH 6 (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 Cs 2 AlGaH 6 and 1.64 wt% for Cs 2 NaGaH 6. Moreover, the Cs 2 AlGaH 6 is found to be effective for hydrogen reduction, while Cs 2 NaGaH 6 is has better performance for oxygen reduction. In conclusion, this study provides evidence that Cs 2 XGaH 6 (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 Cs 2 XGaH 6 (X = Al, Na). • The optimization cures, negative formation energy and tolerance factor show the stability of the studied compounds. • For hydrogen storage, Cs 2 XGaH 6 (X = Al, Na) are attractive contenders due to their low energy losses at maximum absorption. • Photocatalytic properties show the excellent response of Cs 2 XGaH 6 (X = Al, Na) for solar hydrogen synthesis. [ABSTRACT FROM AUTHOR]