Predicting hydrogen storage, mechanical, thermodynamic, and electronic characteristics of perovskite hydrides NaBH₃ (B=Cu, Zn, Cd): A first-principles study

The storage of hydrogen (H₂) has gained sufficient consideration in modern times due to fuel scarcity. Perovskite hydrides are essential for H₂ storage and production applications. This work carefully examines the composition, capacity to store H₂, mechanical, thermodynamic, and electronic characteristics of the hydrides NaBH₃ (B=Cu, Zn, Cd) by utilizing density functional theory (DFT). The tolerance factor found in the range for cubic materials and negative values of formation enthalpy has validated the chemical stability of hydrides. The capability of hydrides to store hydrogen has been evaluated by governing the gravimetric and volumetric storage capacity. The observed gravimetric storage capacities are 3.38 %, 3.31 %, and 2.19 % for NaCuH₃, NaZnH₃, and NaCdH₃, respectively. The desorption temperature has been calculated to evaluate the temperature of the release of hydrogen. The elastic attributes have been elucidated, and they have demonstrated the mechanical stability and brittle nature of hydrides. The determined elastic parameters are utilized to predict the melting temperature, elastic wave velocities, and Debye temperature, which have revealed stability at elevated temperatures. Thermodynamic aspects, such as volume, bulk modulus, and thermal expansion, have been calculated for thermal stability under extreme conditions. The studied hydrides have demonstrated stronger bonding and stability at higher pressure and temperature, making them appropriate for efficient hydrogen storage. The electronic attributes have confirmed the metallic nature of NaCuH₃ and NaZnH₃, whereas NaCdH₃ is a narrow band gap (0.31 eV) semiconductor. The electronic charge density showed less electronic redistribution around constituent atoms, confirming the suitability for H₂ storage applications. Consequently, the hydrides NaCuH₃, NaZnH₃, and NaCdH₃ are effective materials for hydrogen storage applications.