▎ 摘　　要

NOVELTY - The method comprises: (a) adding graphite oxide in a reactor, introducing inert gas into the reactor until the reactor atmosphere is inert environment, stopping the inert gas introduction, adding ammonia gas into the reactor, heating the mixture to react to obtain nitrogen-doped graphene; and (b) adding the nitrogen-doped graphene into ethanol and then ultrasonically dispersing to form a nitrogen-doped graphite suspension, volatilizing the ethanol until the ethanol is completely volatilized and drying the solid product. USE - The method is useful for preparing a nitrogen-doped graphene thin film, which is useful in a capacitor (all claimed). ADVANTAGE - The method is capable of simply, rapidly and economically preparing the nitrogen-doped graphene thin film with high yield thus improving the storage property of the capacitor in a convenient manner. DETAILED DESCRIPTION - The method comprises: (a) adding graphite oxide in a reactor, introducing inert gas into the reactor until the reactor atmosphere is inert environment, stopping the inert gas introduction, adding ammonia gas into the reactor, heating the mixture to react at 800-900 degrees C for 1-3 hours to obtain nitrogen-doped graphene; and (b) adding the nitrogen-doped graphene into ethanol and then ultrasonically dispersing for 2-4 hours to form a nitrogen-doped graphite suspension, volatilizing the ethanol in 40-60 degrees C water bath until the ethanol is completely volatilized and drying the solid product in a vacuum oven at 60 degrees C for 12 hours. The flow speed o the inert gas is 100-300 ml/minute. The flow rate of the ammonia gas is 100-400 ml/minute. The nitrogen-doped graphene suspension has a solubility of 0.2-1 mg/ml. The graphite oxide is prepared by adding 98 mass% of graphite with a purity of 99.5% to 65 mass% of concentrated sulfuric acid or concentrated nitric acid and then mixing and stirring, adding potassium permanganate to the mixture and then heating and oxidizing, adding 30 mass% of hydrogen peroxide solution to the oxidized mixture to remove potassium permanganate, subjecting the mixed solution to suction filtration, and then washing with dilute hydrochloric acid and deionized water and drying to obtain the graphite oxide. INDEPENDENT CLAIMS are included for: (1) a nitrogen-doped graphene thin film; and (2) a capacitor.