Adsorption and Diffusion of Li and Ni on Graphene with Boron Substitution for Hydrogen Storage: Ab-initio Method

Abstract

Based on first-principles plane wave calculations, it has been shown that boron-substituted graphene with Li metal atom adsorption can be used as a high-capacity hydrogen storage material. Boron substitution in graphene increases Li and Ni metal adsorption energy, which is much larger than that in pure graphene. The diffusion characteristics of metal atoms were also investigated. The diffusion energy barrier of Ni metal is stronger than that of Li metal, but the cohesive energy of Ni bulk is much larger. Then, the large-scale metal adsorption behavior on boron-substituted graphene was calculated by the molecular dynamics (MD) method. Moreover, hydrogen adsorption behavior on Li metal atoms is investigated. It is found that Li and Ni adatoms dispersed on the double side of graphene can absorb up to eight hydrogen molecules corresponding to 13.2 and 7.9% hydrogen storage capacities, respectively.