▎ 摘　　要

Hydrogen has a substantial effect on the growth of graphene by metal-based chemical vapor deposition (CVD). However, the specific role of hydrogen under different preparation conditions is difficult to elucidate. Herein, graphene with high coverage was prepared by CVD method on Pt(111). It was found that a certain proportion of hydrogen can accelerate the growth of graphene at 900 K and promote the quality of graphene, as compared to conditions without hydrogen. In situ low-energy electron microscopy revealed that hydrogen entered the interface of graphene and Pt, weakening overlayer-substrate interaction, which was deduced to be the reason for promoting the growth of graphene. This work provides more deep insights into the controllable growth of graphene, owing to the presence of hydrogen.