The DFT study of the structural, hydrogen, electronic, mechanical, thermal, and optical properties of KXH3 (X = Ca, Sc, Ti, & Ni) perovskites for H2 storage applications

Abstract

In this study, we employ density functional theory to investigate KXH₃ (X = Ca, Sc, Ti, & Ni) hydride perovskites for H2 storage applications. Lattice parameters calculated using GGA-PBE are 4.482 Å, 4.154 Å, 3.974 Å, and 3.686 Å for KCaH₃, KScH₃, KTiH₃, and KNiH₃, respectively. Electronic structure analysis shows KScH₃, KTiH₃, and KNiH₃ are metallic, while KCaH₃ is a semiconductor. Strong bonding and long bond lengths indicate high hydrogen storage potential. The materials exhibit thermodynamic and mechanical stability, suggesting feasibility for experimental synthesis. Gravimetric analysis reveals promising hydrogen storage capacities: 3.646 wt% (KCaH₃), 3.452 wt% (KScH₃), 3.346 wt% (KTiH₃), and 3.005 wt% (KNiH₃). Calculated hydrogen desorption temperatures range from 442.40 K to 614.82 K, indicating suitability for practical hydrogen storage applications. These findings highlight the potential of KXH₃ (X = Ca, Sc, Ti, & Ni) perovskites as effective hydrogen storage materials.