▎ 摘　　要

NOVELTY - Composite film comprises graphene and ethyl cellulose. The mass ratio of the graphene to the ethyl cellulose is 1:1.5-20. The composite film comprises a dispersed phase and a continuous phase. The dispersed phase is graphene and the continuous phase is ethyl cellulose. USE - The composite film is useful for preparing electronic device and gas sensor. The gas sensor is useful for detecting acetone, n-hexane, ethanol, and/or nitrogen oxides (all claimed). ADVANTAGE - The composite film has self-supporting property. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) preparing composite film, comprising (i) preparing a liquid phase stripped graphene material to obtain graphene suspension, (ii) preparing ethyl cellulose solution, (iii) mixing the graphene suspension and ethyl cellulose solution, (iv) mixing the mixed liquid obtained in the step (iii), and (iv) volatilizing the solvent to obtain graphene-ethyl cellulose composite film; (2) an electronic device, comprising composite thin film device, the composite film device comprises the composite film; and (3) a gas sensor, comprising composite thin film devices, the composite film device is made of the composite film.