Theoretical prediction of hydrogen storage on Li-decorated monolayer black phosphorus

Based on systematic first-principles density functional calculations, we predict that Li-decorated monolayer black phosphorus (MBP) is a hydrogen storage medium with great potential. It is found that pure MBP has only weak H-2 adsorption energies. Surprisingly, its hydrogen storage properties can be significantly improved after lithium decoration. The calculated Li-binding energy on MBP is higher than the cohesive energy of bulk Li, ruling out the possibility of cluster formations of Li on the MBP surface. Our study shows that Li-decorated MBP can achieve a hydrogen storage capacity as high as 8.11 wt%. The calculated H-2 adsorption energies fall within the range of 0.13-0.18 eV. This is a remarkable result indicating another important application of MBP.