Hydrogen storage application of Zn-based hydride-perovskites: a computational insight

Our investigation focused on an in-depth examination of the physical properties of KZnH₃ and NaZnH₃, with lattice parameters of 4.04 and 3.72 Å, respectively. Both compounds exist stably in a cubic structure and exhibit metallic behavior with no band gap. At the Fermi level, the total and partial densities of states exhibit a significant conductivity, confirming the metallic behavior. These materials have brittle and anisotropic properties. Because of their greater bulk modulus, average shear modulus, and Young’s modulus, NaZnH₃ appears harder compared to KZnH₃. Optical properties indicate significant absorption and optical conductivity in the energy spectrum of 6–9 eV. NaZnH₃ has a greater static refractive index and reflectivity as compared to KZnH₃. The research on hydrogen storage suggests that both of these materials can store hydrogen, however, NaZnH₃ is a more promising candidate due to its higher hydrogen storage capability.