Enhancing hydrogen storage efficiency: The impact of magnesium and calcium decoration on Si4B32 heteroborospherene via DFT analysis

In this study, we investigated the capacity, storage capability, and stability of Si4B32 clusters decorated with Mg and Ca atoms for hydrogen adsorption. All calculations were conducted using density functional theory (DFT). Our analysis revealed that the Si4B32, when decorated with six metal atoms (either Mg or Ca), exhibits a uniform coating without clustering. The unique properties of Mg and Ca, such as low atomic mass and high hydrogen storage capacity, enhance adsorption energies, making them attractive for hydrogen storage. The Mg6Si4B32 and Ca6Si4B32 configurations stored 18 and 36 H2 molecules, respectively, with adsorption energies (Eads) of -0.112 and -0.157 eV/H2, and gravimetric densities of 5.66 wt% and 9.40 wt%, respectively. Additionally, the hydrogen adsorption mechanism, revealed through Quantum Theory of Atoms in Molecules (QTAIM) analysis, involves closed-shell interactions and non-covalent bonding. These results suggest that Mg6Si4B32 and Ca6Si4B32 clusters are promising candidates for H2 adsorption and storage applications.