DFT insights into structural composition, storage capacity, desorption features, elastic, electronic, and thermodynamic aspects of perovskite hydrides NaGaH₃ and NaInH₃ for hydrogen storage applications

Perovskite-type hydrides (PTH) have gained substantial potential for hydrogen (H₂) storage applications. By density functional theory (DFT) analysis, the current investigation elaborates on the electronic, hydrogen storage, chemical composition, thermodynamic, and mechanical properties of NaGaH₃ and NaInH₃. The tolerance factor is estimated to ensure the structural existence, and the formation energy has been calculated for thermodynamic stability. AIMD simulation plots and phonon dispersion curves confirmed the thermal and dynamic stability of both hydrides. The NaGaH₃ and NaInH₃ reveal the gravimetric (3.16 wt%, 2.15 wt%) and volumetric (79.58, 71.80)g.H₂/L H₂ storage capacities with desorption temperatures of 353.55 K and 594.79 K, respectively. The electronic band structures and density of states reveal their metallic nature. The elastic constants' positive values confirm the Born mechanical criteria. The Poisson's ratio and B/G ratio show the brittle nature of NaGaH₃ and NaInH₃. These materials have a low Debye temperature and lattice thermal conductivity with large values of specific heat capacity. Moreover, thermodynamic behavior regarding Debye temperature, Entropy, and thermal expansion has been elaborated in the pressure and temperature ranges 0 to 9 GPa and 0 to 600 K, respectively. Therefore, H₂ storage capacity, with substantially significant trends of thermodynamic behavior, makes these materials suitable for hydrogen storage applications.