▎ 摘　　要

We propose a system that has the potential to be a good candidate for hydrogen storage, in which multiple hydrogen molecules can be adsorbed in the ground state around an impurity in graphene at a certain optimal ILD (interlayer distance). Our first-principles calculations predict that this complex, Ti atoms embedded in double-vacancy graphene (Ti@DV), can hold up to eight H-2 per unit. The hydrogen molecules are not dissociated and are all stored in molecular form, so adsorption and desorption of hydrogen should be feasible. Furthermore, this type of structure is stable throughout the charging and discharging process. The density of states (DOS) of this hydrogen storage medium indicates little charge transfer between H-2 and Ti@DV graphene. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.