Ultrahigh-Capacity Molecular Hydrogen Storage of a Lithium-Decorated Boron Monolayer

Recently, a novel boron monolayer with the "hexagon holes" density of eta = 1/8 was repeatedly predicted to be the most stable boron sheet in different literatures. Its fascinating porous characteristic structure and sufficient surface space seem attractive and motivate researchers to perform further investigation about it. Herein, we demonstrated that the Li-decorated 1/8-boron monolayer is a kind of ultrahigh capacity hydrogen storage medium. We also established that Li atoms can be attached above the centers of the hexagonal holes in the novel 1/8-boron monolayer due to the charge transfer from Li atoms to boron atoms, and the electric field induced by the positive charged Li atoms attracts and polarizes the H-2 molecules and makes the binding strong enough for potential applications to store H-2 molecules but not dissociate them. Detailed calculations showed that the two-sided Li-decorated 1/8-boron monolayer has an ultrahigh hydrogen storage capacity averagely to bind up to four H-2 molecules for each Li atom with an ideal binding energy of 0.23 eV/H-2, which is just in the ideal binding energy scope (0.2-0.4 eV/H-2) for reversible hydrogen storage and corresponding to a hydrogen uptake of 15.26 wt %. These findings suggested a possible method of engineering a new structure for ultrahigh-capacity hydrogen storage materials with the reversible adsorption and desorption of hydrogen molecules, and they were expected to motivate an active line of experimental efforts.