Chemical effect of alkaline-earth metals (Be, Mg, Ca) substitution of BFe2XH hydride perovskites for applications as hydrogen storage materials: A DFT perspective

Abstract

This study investigated the effect of alkaline-earth metals (X = Be, Mg, Ca) substitution of BFe2XH perovskite materials and the potential applications for hydrogen storage utilizing density functional theory (DFT) approach at the GGA-PBE and the HSE06 methods. The mechanical properties of the studied systems demonstrate the mechanical stability of BFe2MgH, making it the most mechanically robust compound. While the Pugh ratio suggests that BFe2BeH was brittle, while BFe2CaH showed greater ductility, anisotropic factors confirm that all compounds are anisotropic, indicating directional dependence in their properties. The electronic band structure analysis using the HSE06 and the GGA-PBE suggests that the studied perovskites are metallic due to a calculated bandgap of zero. In terms of optical/optoelectronic properties, BFe2MgH exhibits the highest optical conductivity, absorption coefficient, and energy loss function, indicating its superior ability to absorb light and transfer electrons. For practical applications, the hydrogen storage capacity is assessed, with BFe2BeH showing the highest gravimetric and volumetric capacities. These promising results suggest the potential use of BFe2BeH as an efficient material for hydrogen storage.