A Computational Study of Metal Hydrides Based on Rubidium for Developing Solid‐State Hydrogen Storage

In this work, we explore the physical properties of RbXH 3 (X=Cr, Zr) perovskite hydrides for solid‐state hydrogen storage. The structural, mechanical, electronic, optical, and hydrogen storage properties were theoretically investigated using density functional theory and CASTEP software. The selected candidates were fully relaxed and optimized in the cubic phase space group Pm‐3 m. The structural phase stability was verified by means of thermodynamic, dynamic and mechanical stabilities. Mechanical analyses based on Poisson's ratio (ν), G/B ratio, and Cauchy pressure show that RbCrH 3 and RbZrH 3 exhibit brittle behavior with preference of ionic bonding. The electronic structures unveil half‐metallicity in RbCrH 3 compound and metallic‐like behavior in RbZrH 3 . Furthermore, optical calculations were also conducted to gain additional insights into the physical properties of RbXH 3 compounds. The gravimetric hydrogen storage (C w t % ) capacities have been calculated as 2.09 wt % and 1.64 wt % for RbCrH 3 and RbZrH 3 , respectively. The hydrogen desorption temperatures have been obtained as 545.11 K and 548.15 K for RbCrH 3 and RbZrH 3 , respectively. Our calculation propose RbCrH 3 hydride as potential material for hydrogen storage application.