▎ 摘　　要

NOVELTY - Nitrogen-doped graphene quantum dot (N-GQD) and graphite-phase carbon nitride composite photocatalyst comprises 95-98% graphite-phase carbon nitride and remaining amount of N-GQDs. USE - Used as N-GQD and graphite-phase carbon nitride composite photocatalyst. ADVANTAGE - The composite photocatalyst: has higher visible light response range, high catalytic activity, good stability and long service life. The method: ensures preparation of the composite photocatalyst, which reduces the preparation of graphite-phase carbon nitride, and can firmly combine on N-GQDs surface and increases catalytic activity and stability of the catalyst. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparation of the composite photocatalyst, comprising (a) preparation of N-GQDs by dissolving citric acid and urea in distilled water, transferring the solution into a stainless steel high pressure reaction kettle, heating to 160 degrees C, maintaining constant temperature for 4 hours to obtain reaction liquid, adding ethanol to the reaction liquid, centrifuging at 60 degrees C at 8000 revolutions per minute for 10 minutes to obtain a solid, removing unreacted citric acid and urea from the obtained solid by ethanol, (b) dissolving urea in aqueous solution containing N-GQDs, drying, calcining the aqueous solution at 450-600 degrees C for 3 hours, cooling to room temperature, grinding the obtained solid product to obtain N-GQDs/graphite-phase carbon nitride composite photocatalyst at 20 degrees C/minute in an alumina crucible with cover and (c) photo-deposition by adding chloroplatinic acid aqueous solution and N-GQDs/graphite-phase carbon nitride into 10-40 vol. ethanol aqueous solution, magnetically stirring at room temperature, irradiating under 300 W xenon lamp for 0.5-2.5 hours, centrifugally separating, and drying solid product at 60 degrees C.