Exploring Zr-based perovskite hydrides XZrH3 (X: Na/Cs) for hydrogen storage applications: Insights from first-principles DFT calculations

Abstract

Perovskite hydrides have recently received significant attention as materials for hydrogen storage applications, offering potential advancements in addressing the energy crisis. In this study, we investigated the structural, mechanical, thermodynamic, electronic, magnetic, and optical properties as well as the hydrogen storage performance of the perovskite hydrides XZrH₃ (X: Na/Cs) using density functional theory (DFT). The negative values of the formation enthalpies, along with the assessment of the elastic constants and thermodynamic parameters, both NaZrH₃ and CsZrH₃, exhibit stability in the cubic structure, and their zero-band gap energy validates their metallic nature. The mechanical properties indicated that the materials exhibited ionic bonding along with exceptional hardness behavior, with NaZrH₃ demonstrating greater stiffness than CsZrH₃. Furthermore, both the materials exhibited anisotropic properties. The magnetic characteristics of these compounds were thoroughly examined and determined to be non-magnetic, and their dynamic stability was evaluated by analyzing the phonon dispersion curve. The computed gravimetric hydrogen storage capacities for NaZrH₃ and CsZrH₃ are 2.51 wt% and 1.31 wt%, respectively. These results provide valuable insights into XZrH₃ (X: Na/Cs) materials as promising candidates for efficient hydrogen storage.