First-Principles Investigation of Structural, Electronic, and Hydrogen Storage Properties of Al-Based Perovskite Hydrides XAlH 3 (X = Ga, In, Tl)

Abstract

The global movement toward sustainable energy has created growing interest in green hydrogen as a key technology for future energy systems. However, the safe and efficient storage of hydrogen remains a significant challenge. In this study, first-principles calculations were used to examine the phase stability, optoelectronic behavior, and hydrogen storage capability of Al-based metal perovskites XAlH 3 (X = Ga, In, and Tl). The main aim of the research was to assess whether these metal perovskite hydrides could be suitable for solid-state hydrogen storage applications. The calculated formation energies and elastic constants confirm that the XAlH 3 compounds are thermodynamically and mechanically stable. In addition, the positive phonon dispersion results show that all three materials are dynamically stable. The electronic band structure analysis indicates that these hydrides have metallic characteristics. Furthermore, the estimated B/G ratio and Cauchy pressure values suggest that the XAlH 3 materials possess ductile behavior. We also investigated the optical responses of XAlH 3 hydrides in detail. The thermal stability of these hydrides was confirmed by the thermodynamic evaluations and AIMD simulations. The calculated gravimetric hydrogen capacity of GaAlH 3 , InAlH 3 , and TlAlH 3 is found to be 3.03, 2.09, and 1.29 wt%, respectively. Furthermore, the calculated volumetric hydrogen storage capacities for GaAlH 3 , InAlH 3 , and TlAlH 3 are 96.66, 86.63, and 82.43 gH 2 /L, respectively. Desorption temperatures for GaAlH 3 , InAlH 3 , and TlAlH 3 are 397.53 K, 555.64 K, and 218.06 K, respectively. Overall, this study indicates that Al-based perovskite hydrides may be promising materials for solid-state hydrogen storage, and the investigation of XAlH 3 hydrides offers a useful pathway for advancing hydrogen storage technologies.