Method for preparing graphene

The invention discloses a method for preparing graphene, which is implemented in a way that: in a chemical vapor deposition process, a catalyst is utilized to activate the properties of carbon dioxide, and hydrogenation reaction is carried out to grow graphene on a copper substrate. The flow rate of the carbon dioxide is controlled to change the concentration of the carbon source, thereby achieving the effect of shape evolution. Compared with the traditional method, the method disclosed by the invention greatly enhances the controllable degree of the shape in the graphene preparation process, and prepares the hexagonal-to-round graphene in a controllable way.