▎ 摘　　要

NOVELTY - Preparation of graphene film comprises mixing natural graphite and concentrated sulfuric acid and pretreating at low temperature of 0-12 degrees C to obtain pretreated liquid, mixing with oxidant, performing heat preservation to obtain expanded graphite, mixing with alcohol solvent, performing ultrasonic dispersion to obtain graphene solution, and filtering to form film. USE - The method is used for preparation of graphene film. ADVANTAGE - The use of low temperature pretreatment moves sulfuric acid molecule to graphite intercalation edge, which saves time for succeeding reaction with oxidant, shortens reaction path length, consumes less concentrated sulfuric acid and reduces discharge of waste liquid. The method has low cost and simple operation, and does not need high temperature or preparation under special environmental conditions, which greatly reduces energy consumption. The prepared graphene has thin layers and less defect. The method can realize preparation of large area graphene film.