▎ 摘　　要

NOVELTY - The preparation method of nitrogen-doped graphene quantum dots involves immersing carbon fiber in mixed acid, ultrasonically processing, heating, cooling, adding the reaction liquid into deionized water and mixed acid, dialyzing using deionized water to obtain graphene quantum dots aqueous solution with light yellow fluorescence under irradiation of 365 nm UV lamp, mixing graphene quantum dots aqueous solution, nitrogen, and N-dimethylformamide preparation with nitrogen to prepare nitrogen-dimethylformamide aqueous solution, mixing two solutions, and ultrasonically processing. USE - Preparation method of nitrogen-doped graphene quantum dots by high energy electron beam irradiation method (claimed). ADVANTAGE - The method enables preparation of nitrogen-doped graphene quantum dots by simple and industrial process. DETAILED DESCRIPTION - The preparation method of nitrogen-doped graphene quantum dots involves (A) immersing carbon fiber in mixed acid, ultrasonically processing at room temperature for 1-2 hours, heating at reflux for 18-36 hours, where the mixing acid comprises 98% concentrated sulfuric acid and 63% concentrated nitric acid mixture in volume ratio of 3:1, cooling to room temperature, adding the reaction liquid into 5-10 times of deionized water and mixed acid, dialyzing using deionized water for 5 days with 3500 cut-off molecular weight to obtain graphene quantum dots aqueous solution with light yellow fluorescence under irradiation of 365 nm UV lamp, (B) mixing 0.5-1 mg/ml graphene quantum dots aqueous solution, nitrogen, and N-dimethylformamide preparation with 5-95% nitrogen to prepare nitrogen-dimethylformamide aqueous solution, mixing two solutions and ultrasonically processing at room temperature for 10-30 minutes, pouring in polyethylene film bag, discharging large amount of air and nitrogen, thermally sealing bag when the thickness of aqueous solution is less than or equal to 1 cm, (C) placing the polyethylene film bag containing solution obtained in step (B) on conveyor belt used for irradiation of the electron accelerator, irradiating at room temperature with an electron beam having beam intensity of 8 mA at 280-560 kGy, and (D) dialyzing the solution obtained in step (C) using deionized water for 5 days to obtain pure nitrogen doped graphene quantum dots aqueous solution, freezing and drying.