▎ 摘　　要

NOVELTY - Method for preparing small-sized graphene quantum dots involves (a) adding graphite into deionized water in graphite aqueous solution, (b) dispersing the aqueous solution of graphite in ultrasonic equipment for 1-4 hours, (c) heat-treating the dried graphite in an inert gas atmosphere with a reasonable process to obtain heat-treated graphite, (d) irradiating the heat-treated graphite with gamma rays in an oxygen-containing medium under appropriate conditions to obtain irradiated graphite, (e) adding concentrated sulfuric acid and concentrated phosphoric acid, (f) ultrasonically dispersing the prepared graphite oxide in an ultrasonic device for a certain time to obtain a graphene oxide solution, (g) adding graphene oxide solid and N,N-dimethylformamide solution, (h) transferring the homogeneous graphene oxide suspension to the reactor, and (i) filtering the suspension lined in the reactor to obtain a dimethylformamide solution of graphene quantum dots with small size. USE - The method is used for preparing small-sized graphene quantum dots. DETAILED DESCRIPTION - Method for preparing small-sized graphene quantum dots involves (a) adding graphite into deionized water in a concentration of 1-6 mg/ml graphite aqueous solution, (b) dispersing the aqueous solution of graphite in ultrasonic equipment for 1-4 hours, freeze-drying the aqueous solution of graphite after ultrasonic treatment to obtain dried graphite, (c) heat-treating the dried graphite in an inert gas atmosphere with a reasonable process to obtain heat-treated graphite, (d) irradiating the heat-treated graphite with gamma rays in an oxygen-containing medium under appropriate conditions to obtain irradiated graphite, (e) adding concentrated sulfuric acid and concentrated phosphoric acid at the ratio of 9:1, stirring and mixing the two acids evenly, transferring the mixed acid solution to a container of suitable specifications and heating at a constant temperature of 50 degrees C, stirring the mixed acid solution at a constant rate, adding the irradiated graphite and potassium permanganate at the ratio of 1:6, and adding the two to the mixed acid solution with stirring, obtaining graphite oxide solution after full reaction, obtaining high-purity graphite oxide solution after multiple centrifugal washings, (f) ultrasonically dispersing the prepared graphite oxide in an ultrasonic device for a certain time to obtain a graphene oxide solution, and freeze-drying the graphene oxide solution to obtain a graphene oxide solid, (g) adding graphene oxide solid and N,N-dimethylformamide (DMF) solution, mixing the two to obtain a dimethylformamide solution of graphene oxide, ultrasonically dispersing the prepared dimethylformamide solution of graphene oxide for 10-90 minutes to form a uniform suspension, (h) transferring the homogeneous graphene oxide suspension to the reactor, heating under appropriate conditions, cooling to room temperature after the reaction, where the suspension in the lining of the reactor comprises brown suspension and black precipitate, and (i) filtering the suspension lined in the reactor, and collecting the filtrate to obtain a dimethylformamide solution of graphene quantum dots with small size.