A first-principles study on double-sided decorated boron–nitrogen co-doped graphene by vanadium for enhanced low-temperature reversible hydrogen storage

Abstract

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 V₃ atoms stably adsorb on the BNDG sheet without clustering at both lower and higher temperature. We show that up to 8 H₂ molecules adsorb on a single side, and up to 18 H₂ molecules can adsorb on double sided V₃ decorated BNDG. We also explored the effects of the external electric field on H₂ adsorption on the V₃/BNDG sheet and found that the adsorption strength of H₂ molecules on the V₃ 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 V₃/BNDG sheets upon hydrogen adsorption are analyzed. The corresponding hydrogen gravimetric density of the double-sided decorated V₃/BNDG sheet is 6.43%, which reaches the DOE target. Our theoretical results demonstrate that the V₃ decorated BNDG sheet could serve as a promising solid-state medium for hydrogen storage.