▎ 摘　　要

Conventional synthesis of graphene film by chemical vapor deposition (CVD) on a metal substrate, which may require damaging and polluting processes to transfer graphene onto an insulating substrate for possible applications subsequently, needs to be improved. In the past few years, molten gallium, as a kind of catalyst for synthesizing graphene film, has presented various unique properties, especially showing excellent catalytic efficiency and forming graphene channel patterns naturally as expected. Herein, we utilized molten Ga as the catalyst and silicon dioxide as the substrate to realize the synthesis of high-quality and single-layer graphene film by low-pressure CVD at 800 degrees C similar to 1000 degrees C. What's more, the Ga catalyst, which still contained graphene nuclei even though it had been recycled several times, contributed to synthesizing single-layer graphene film even at 400 degrees C for both economy and environment sake.