An Ab-initio simulation of boron-based hydride perovskites XBH₃ (X = Cs and Rb) for advance hydrogen storage system

Density functional theory (DFT) was employed in the CASTEP to examine the structural, electronic, optical, hydrogen and elastic characteristics of cubic perovskites XBH₃ (X = Cs and Rb). The optimization has been completed using generalized gradient approximation (GGA) within the scheme of Perdew, Burke and Ernzrhof (PBE). The structural findings demonstrated the stability of both compounds. The study of electronic band structure and density of states (DOS) reveal the strong evidence of metallic behavior for XBH₃ (X = Cs and Rb) perovskites. The optical properties of XBH₃ (X = Cs and Rb) have been carried out and are discussed in this paper as well. The mechanical properties like Young's modulus, Bulk modulus etc. have been deduced from elastic values. The calculated elastic constants also satisfy the criteria for material bonding and ductility. The compounds under investigation showed anisotropic behaviour. For CsBH₃ and RbBH₃, the gravimetric ratio for hydrogen storage is found to be 2.19 wt% and 3.01 wt%, respectively. For the first time, computational analyses have been carried out on these hydrides. This could lead to huge improvements in the ways hydrogen can be stored.