Perovskite hydrides XBH3 (X = Mg, Ca; B = Ga, In) for hydrogen storage: A DFT investigation of structural, thermodynamic, elastic, and electronic characteristics.

This paper explores the crystal structure, formation energies, thermodynamic properties, elastic constants, electronic structure, and H2 storage properties of XBH3 (X = Mg, Ca; B=Ga, In) hydrides utilizing the density functional theory (DFT) as modeled in the WIEN2k program. To determine the stability and practicability of these materials in hydrogen storage applications, thermodynamic and mechanical parameters were determined. Calculations of the electronic structure show that band gaps of MgGaH3, CaGaH3, MgInH3, and CaInH3 are 1.46 eV, 1.63 eV, 0.89 eV, and 1.35 eV, respectively. Gravimetric storage capacities of 3.12 wt%, 2.68 wt%, 2.13 wt%, and 1.91 wt% are observed for MgGaH3, CaGaH3, MgInH3, and CaInH3, respectively. The volumetric storage densities are found to be 85.97 gH2/L, 62.72 gH2/L, 77.88 gH2/L, and 60.17 gH2/L, and hydrogen desorption temperatures generated by reaction enthalpies were found to be 734.20 K, 719.43 K, 877.12 K, and 886.91 K, respectively. Ab initio molecular dynamics (AIMD) simulation reveals that MgGaH3, CaGaH3, and MgInH3 are thermodynamically stable, whereas CaInH3 is unstable at 300 K and 500 K. Phonon dispersion analysis confirms the dynamic stability of all hydrides. All these findings offer important insights for designing and optimizing future hydrogen storage materials, which will lead to the advancement of hydrogen-based energy technologies.