Rb-based cubic hydride perovskites: A comprehensive DFT study for hydrogen storage applications

Although hydrogen is a clean and sustainable energy carrier, however, its storage is still a great challenge. This study investigates the physical characteristics of the perovskite-type hydrides RbSH 3 and RbSeH 3 as well as their hydrogen storage potential by using first-principles calculations. The lattice parameters of RbSH 3 and RbSeH 3 are found to be 3.99 and 4.13[Formula: see text]Å, respectively. Both compounds were analyzed using Mulliken and Hirshfeld populations. Stability tests at 300 K with Ab Initio Molecular Dynamics (AIMD) simulations have shown that both materials are stable. The electronic properties show that both materials act as metals due to their zero band gap. The optical properties indicate that there are high levels of light absorption, which are vital in photo-assisted hydrogen storage systems. Both hydrides exhibit mechanical stability, ionic character and ductile nature. The gravimetric hydrogen storage capacity of RbSH 3 and RbSeH 3 is found to be 1.81% and 2.51%, respectively. The heat of formation, desorption temperature and reaction pathways have also been reported. The presented results are of vital importance in the design of hydrogen storage materials for the future.