▎ 摘　　要

NOVELTY - Preparing metal surface graphene/polypyrrole protective composite film comprises e.g. uniformly mixing 2 g natural graphite, 1 g phosphorus pentoxide, 10 ml concentrated sulfuric acid (98%) and 1 g potassium persulfate by stirring, carrying out pre-oxidation reaction at 80-90 degrees C for 0.5-18 hours, naturally cooling to 20-25 degrees C, placing it stationary for 6-8 hours, diluting by adding distilled water, filtering, washing to neutrality with water, drying to obtain pre-oxidized graphite, uniformly mixing pre-oxidized graphite and 46 ml concentrated sulfuric acid, controlling the reaction system. USE - The method is useful for preparing metal surface graphene/polypyrrole protective composite film (claimed). ADVANTAGE - The composite film enhances the corrosion resistance of the metal (claimed). The method is simple, highly efficient and does not cause pollution. DETAILED DESCRIPTION - Preparing metal surface graphene/polypyrrole protective composite film comprises: (i) uniformly mixing 2 g natural graphite, 1 g phosphorus pentoxide, 10 ml concentrated sulfuric acid (98%) and 1 g potassium persulfate by stirring, carrying out pre-oxidation reaction at 80-90 degrees C for 0.5-18 hours, naturally cooling to 20-25 degrees C, placing it stationary for 6-8 hours, diluting by adding distilled water, filtering, washing to neutrality with water, then drying to obtain pre-oxidized graphite; (ii) uniformly mixing pre-oxidized graphite and 46 ml concentrated sulfuric acid, controlling the reaction system temperature to 10-20 degrees C under an ice bath, slowly adding 6 g potassium permanganate powder under constant stirring condition, placing the reaction system under an oil bath, stirring at 35-38 degrees C for 2-2.5 hours, adding 100 ml distilled water to dilute and continuing to react for 15-20 minutes, adding 300 ml distilled water to terminate the reaction, adding 5-8 ml aqueous hydrogen peroxide (30%) until the mixture turns golden yellow, then stopping adding and carrying out suction filtration, rinsing the precipitate with 10 times amount of 5% aqueous hydrochloric acid to obtain graphene oxide aqueous dispersion liquid; (iii) diluting the graphene oxide aqueous dispersion liquid to 1 mg/ml concentration using distilled water, adding 10 mg pyrrole to each 10 ml of graphene oxide aqueous dispersion phase (i.e. in a ratio of 1:1), subjecting the mixture to ultrasonic dispersion to obtain a stable solution of graphene oxide pyrrole, passing nitrogen gas for 30-40 minutes to remove oxygen from the solution to prevent oxidative polymerization; (iv) placing a metal sheet (working electrode), a saturated silver chloride electrode (reference electrode) and a platinum electrode (auxiliary electrode) in the graphene oxide pyrrole solution, carrying out electrodeposition process using a commercially available electrochemical workstation, applying voltage to determine the size and duration using different types of metal sheet, where the metal sheet surface is deposited with a layer of graphene oxide/polypyrrole film, removing the metal sheet and washing 2-3 times with distilled water, then drying in an oven at 50-60 degrees C for 3-4 hours; and (v) placing the dried metal sheet in 50 g/l aqueous sodium sulfate solution, passing nitrogen for 30-40 minutes, subjecting the metal sheet to cyclic voltammetry curve method with a voltage of -1.5 to 0 V, scanning 10 laps with a scan rate of 50 mV/second to reduce graphene oxide of the film to graphene, rinsing the metal sheet with distilled water, then drying in an oven at 50-60 degrees C for 3 hours to achieve deposition of graphene/polypyrrole composite film on metal surface.