Titanium-embedded graphene as high-capacity hydrogen-storage media

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 H2 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 H2 and Ti@DV graphene.

► A new model with Ti atom embeded into graphene for hydrogen storage is proposed. ► The first hydrogen molecule doesn’t dissociate. ► There is little charge transferred among Ti atom, graphene and H2. ► Four H2 molecules can be adsorbed on each side of the layer.