Be12S12 nano-cage: A Promising Hydrogen Storage Medium From a theoretical point of view

In recent years, much effort has been dedicated to fabricate nanostructures, which can absorb hydrogen molecules with high storage capacity. Different nanostructured materials have been studied in detail to enhance hydrogen storage capacity. Hydrogen storage materials must represent appropriate thermodynamic properties and have sufficiently prompt kinetics of H2 charging and discharging. Therefore, seeking novel hydrogen storage materials has remained an important issue. Recently, the adsorption of some gases such as H2O, CH4, NH3, H2 and CO on BeO nanomaterial has been studied [1,2]. Nonetheless, several materials, like as aluminum nitride (AlN) nanostructures [3], boron nitride (BN) systems [4] and fullerene clusters [5], boron buckyballs and sheets, B80 [6] have been tested experimentally and theoretically as potential storage materials for hydrogen. First-principles calculations based on density functional theory were performed to study the hydrogen adsorption and H2 storage on the beryllium sulfide nano-cage (Be12S12 nanocage). The adsorption of H2 molecules on the nano-cage depends on the polarization and charge of the atom surface. The transfer of charge from the Be atom to its neighboring S atoms in the surface of the cluster indicates the ionic character of the Be–S bond, so that Be–S bonds are polarized. The results show that the H2 molecule is significantly adsorbed on the Be12S12 nano-cage surface, so that the H2 prefers to be adsorbed atop a Be atom as compared to solfur atoms of the cluster surface. Our calculations also reveal that the gravimetric uptake can overpass the value of 7.6 wt % with an average adsorbed energy (Eads) of -0.89 eV. These findings have important implications on designing of hydrogen storage materials and significantly broadening the spectrum of strategies for fabricating of new nanostructures to enhance hydrogen storage capacity.