▎ 摘　　要

NOVELTY - A method for preparing a graphene sheet by using a supercritical fluid, comprising: providing graphite oxide or expandable graphite; performing a supercritical fluid intercalation step, wherein the graphite oxide or the expandable graphite and the urea aqueous solution are intercalated by a supercritical fluid, and then stir by nitric acid with ultrasonically oscillated and filtered. The urea nitrate intercalation graphite can be obtained. Finally it performs an microwave expansion step, wherein the graphene is obtained by the urea nitrate intercalated graphite at a predetermined temperature by microwave heating, and is pulverized by a pulverizer to obtain a graphene sheet.