▎ 摘　　要

NOVELTY - Preparing graphene film comprises adding multi-walled carbon nanotubes to a mixed solution e.g. concentrated sulfuric acid, ultrasonically processing, adding deionized water, washing, adding ethylene glycol and potassium hydroxide solution, shaking, washing, drying to obtain surface-hydroxylated multi-walled carbon nanotubes, ultrasonically dispersing graphene oxide in dimethylformamide, adding e.g. sodium hydroxide, filtering, drying to obtain carboxylated graphite oxide, adding surfactant to e.g. carboxylated graphite oxide, stirring, drying to obtain surface carboxylated graphene, ball milling hydroxylated multi-walled carbon nanotubes , adding triton, ultrasonically dispersing to obtain a suspension hydroxylated multi-walled carbon nanotubes, adding thionyl chloride to suspension and surface carboxylated graphene, stirring, filtering to obtain a carbon nanotube-graphene composite liquid and spraying on a clean glass plate, laminating, drying and winding to form a coil. USE - The method is useful for preparing graphene film. ADVANTAGE - The graphene has better strength, toughness and electrical conductivity. The method has a synergistic effect between the graphene and the carbon nanometer and improves the mechanical strength and the electrical and thermal conductivity of the graphene film. DETAILED DESCRIPTION - Preparing graphene film comprises (a) adding multi-walled carbon nanotubes to a mixed solution of concentrated nitric acid and concentrated sulfuric acid having a ratio of 1:1.5-3, ultrasonically processing at 40-60 degrees C for 4-8 hours, adding deionized water, washing to pH of 7, adding ethylene glycol solution and potassium hydroxide solution dropwise , ultrasonically shaking for 5-12 hours, washing with water to the pH of 7, drying to obtain surface-hydroxylated multi-walled carbon nanotubes, (b) ultrasonically dispersing the graphene oxide in dimethylformamide, adding sodium hydroxide and succinic acid peroxide, continuing ultrasonification , controlling to 75-90 degrees C for 2-3 hours, filtering, washing, drying to obtain carboxylated graphite oxide, where the ratio of graphene oxide, sodium hydroxide, succinic acid peroxide and dimethylformamide is 1: (10-13): (10-13): (15-20) mmol/ml, adding surfactant to the carboxylated graphite oxide, ultrasonically processing for 10- 20 minutes, adding diazonium solution, 35-38 wt.% concentrated hydrochloric acid (2.5 ml) at 0-4 degrees C, stirring for 8-10 hours, stirring at room temperature for 5-8 hours, washing, filtering, drying to obtain surface carboxylated graphene, where the ratio of carboxylated graphite oxide and the diazonium salt solution is 1g: (0.8-0.9) ml, (c) ball milling the hydroxylated multi-walled carbon nanotubes , adding 1-3 wt.% triton, ultrasonically dispersing for 1.5-2.5 hours to obtain a suspension hydroxylated multi-walled carbon nanotubes having a concentration of 3-5 mg/ml, adding thionyl chloride to the suspension and the surface carboxylated graphene, stirring at 50-60 degrees C for 4-6 hours, filtering to obtain a carbon nanotube-graphene composite liquid, where the ratio of hydroxylated multi-walled carbon nanotubes, surface carboxylated graphene and the thionyl chloride is 1 g: (1.2-1.6) g: (0.1-0.3) ml and (d) spraying the carbon nanotube-graphene composite liquid on a clean glass plate, laminating the film with a thickness by using a laminating machine, placing the graphene film in a temperature-programmed oven, drying and winding to form a coil.