▎ 摘　　要

Boron-nitrogen co-doped graphene (BNDG) sheet is decorated with Ti and V metal atoms, and their structural and thermal stability towards hydrogen adsorption is investigated using first principles calculations. The Ti and V trimers exhibit stronger binding strengths on the BNDG sheet than other considered transition metal atoms. However, our results suggest that the Ti atoms are not suitable for decorating the BNDG sheet though they have a larger binding energy than the V atoms, as they tend to form clusters on the BNDG surface. However V-3 atoms stably adsorb on the BNDG sheet without clustering at both lower and higher temperature. We show that up to 8 H-2 molecules adsorb on a single side, and up to 18 H-2 molecules can adsorb on double sided V-3 decorated BNDG. We also explored the effects of the external electric field on H-2 adsorption on the V-3/BNDG sheet and found that the adsorption strength of H-2 molecules on the V-3 decorated BNDG sheet can be strengthened/weakened and thereby hydrogen adsorption/desorption can be easily achieved. The effects of pressure on the structural stability of the V-3/BNDG sheets upon hydrogen adsorption are analyzed. The corresponding hydrogen gravimetric density of the double-sided decorated V-3/BNDG sheet is 6.43%, which reaches the DOE target. Our theoretical results demonstrate that the V-3 decorated BNDG sheet could serve as a promising solid-state medium for hydrogen storage.