▎ 摘　　要

NOVELTY - Preparing graphene comprises: (i) placing a quartz boat containing a methanation catalyst, and a substrate on the same plane along the gas flow, and then placing quartz tube in an electric furnace, and the substrate at the center of the electric furnace, heating hydrogen so as to make the temperature at center of the electric furnace to be 800-1050 degrees C, and annealing under stable condition; (ii) heating the quartz boat containing methanation catalyst, filling carbon and hydrogen gas into the quartz boat to carry out chemical vapor deposition, growing graphene on the substrate, and depositing. USE - The method is useful for preparing graphene (claimed). ADVANTAGE - The flow rate of the carbon dioxide is controlled to change the concentration of the carbon source, thus achieving the effect of shape evolution. The method greatly enhances the controllable degree of the shape in the graphene preparation process, and prepares the hexagonal-to-circular graphene in a controllable way. DETAILED DESCRIPTION - Preparing graphene comprises: (i) placing a quartz boat containing a methanation catalyst, and a substrate on the same plane along the gas flow, and then placing quartz tube in an electric furnace, and the substrate at the center of the electric furnace, heating hydrogen so as to make the temperature at center of the electric furnace to be 800-1050 degrees C, and and annealing under stable condition for 10-60 minutes; (ii) maintaining constant temperature at the center of the furnace, heating the quartz boat containing methanation catalyst to 50-300 degrees C, filling carbon and hydrogen gas into the quartz boat to carry out chemical vapor deposition, growing graphene on the substrate, depositing after introducing argon and hydrogen mixed gas, and cooling to obtain the graphene on the substrate. An INDEPENDENT CLAIM is also included for graphene, prepared as mentioned above.