Exploration of Physical Properties of Sodium‐Based Perovskite Hydrides ANaH3 (A = Hf, Nb, Pd, Ru) for Hydrogen Storage Applications: First Principles Study

Abstract

In this work, first‐principles density functional theory (DFT) was used to investigate the structural, mechanical, thermodynamic, electronic, and hydrogen storage properties of sodium hydride perovskites ANaH3 (A = Hf, Nb, Pd, Ru). All compounds crystallize in a stable cubic perovskite structure with negative formation energies. Ab initio molecular dynamics simulations at 500 K show minimal energy fluctuations, and phonon analysis confirms dynamical stability. Mechanical properties indicate overall stability, with HfNaH3, NbNaH3, and RuNaH3 being ductile, while PdNaH3 is slightly brittle. The calculated Debye temperatures (818.17–945.61 K) suggest high lattice rigidity and thermal stability. Electronic structure results reveal metallic behavior for HfNaH3 and NbNaH3, whereas PdNaH3 and RuNaH3 exhibit narrow indirect bandgaps. Density of states analysis indicates strong hybridization between transition metal d and hydrogen s orbitals, reflecting robust metal–hydrogen interactions. Hydrogen storage performance shows gravimetric capacities of 1.48–2.54 wt.% and volumetric capacities of 100.49–118.93 gH2L−1, with desorption temperatures of 280.52–369.11 K, indicating favorable low‐temperature hydrogen release. Finally, these findings provide critical insights into the design and optimization of sodium‐based hydride perovskites as efficient and reversible hydrogen storage materials.