▎ 摘　　要

NOVELTY - A graphene powder is prepared by adding 10 g of graphite into mixture of strong oxidized acid and nitrate, adding potassium-containing strong oxidant, reacting for 20-40 minutes in water bath, adding hydrogen peroxide solution and 100 mL of water, and obtaining oxidized graphite solid; dissolving the oxidized graphite into solvent, vibrating, and obtaining oxidized graphene solution; centrifugally processing the oxidized graphene solution; and placing the oxidized graphene solution into super-critical reaction kettle. USE - Method for preparing graphene powder (claimed). ADVANTAGE - The method has high production efficiency and is up to 100%; and has high yield and less environmental pollution. DETAILED DESCRIPTION - Preparing graphene powder comprises: (A) adding 10 g of graphite into mixture of strong oxidized acid and nitrate, a mass ratio of the nitrate to graphite being 0.2-1:1 and a mass ratio of the strong oxidized acid to graphite being 2-30:1, cooling to 0-5 degrees C, agitating for 30-40 minutes, continuing agitating and adding potassium-containing strong oxidant, a mass ratio of the potassium-containing strong oxidant to graphite being 0.4-6:1, heating up to 10-15 degrees C, continuing agitating for more than 12 hours, continuing reacting for 20-40 minutes in water bath with liquid introducing temperature of 30-40 degrees C, slowly adding 200 mL of water, heating up to 90-100 degrees C and preserving the temperature for 35 minutes, adding hydrogen peroxide solution and 100 mL of water, a mass ratio of hydrogen peroxide solution to graphite being 0.2-1:1, continuing agitating for 2 hours, alternatively cleaning for 4 times using hydrochloric acid (5 mass%) and water, washing using clear water, filtering, drying filter cake, grinding, sieving, and obtaining the oxidized graphite solid; (B) dissolving the oxidized graphite into solvent (water, ethanol, acetone, tetrahydrofuran or N,N-dimethyl formamide), vibrating for 0.5-12 hours at 300-120 W, and obtaining oxidized graphene solution; (C) centrifugally processing the oxidized graphene solution, collecting supernatant solution, and obtaining oxidized graphene solution; and (D) placing the oxidized graphene solution into super-critical reaction kettle, under protection of inert gas and at 20-100 MPa, controlling the reaction temperature to more than the super-critical temperature of the solvent, reacting for 1-24 hours, naturally cooling the reaction kettle or chilling by using water, and slowly discharging the gas in the kettle to obtain the graphene powder.