▎ 摘　　要

NOVELTY - Preparation of mesoporous niobium pentoxide/nitrogen-doped graphene composite photocatalyst involves mixing nitrogen-doped graphene oxide solution and mesoporous niobium pentoxide, adding ethanol, stirring under mercury lamp condition to perform reduction process, drying and washing. The nitrogen-doped graphene oxide solution is prepared by adding ground graphene oxide and urea to a tubular furnace, washing, drying, dissolving obtained powder in distilled water, removing precipitate after 24 hours of natural sedimentation, adding ethanol, and ultrasonically processing. USE - Preparation of mesoporous niobium pentoxide/nitrogen-doped graphene composite photocatalyst (claimed). ADVANTAGE - The method enables efficient preparation of environmentally-friendly mesoporous niobium pentoxide/nitrogen-doped graphene composite photocatalyst with improved interfacial bonding of graphene and mesoporous niobium pentoxide, electron transfer performance by modifying graphene oxide by non-metal nitrogen, and photocatalytic efficiency. The photocatalyst rapidly and effectively decomposes water to produce hydrogen, and high recovery rate. DETAILED DESCRIPTION - Preparation of mesoporous niobium pentoxide/nitrogen-doped graphene composite photocatalyst involves uniformly mixing each 0.1-0.5 mg/ml nitrogen-doped graphene oxide solution and mesoporous niobium pentoxide, adding 40 ml ethanol, ultrasonically processing at 500 W for half an hour, stirring for 6-10 hours under mercury lamp condition to perform reduction process, drying obtained solution at 60 degrees C, and centrifugally washing with absolute ethanol for several times. The content of nitrogen-doped graphene is adjusted by adding different amount of nitrogen-doped graphene oxide solution. The prepared composite photocatalyst is labeled with m-Nb2O5/NGR-x, where x is content of nitrogen-doped graphene. The nitrogen-doped graphene oxide solution is prepared by grinding 0.5-1 g graphene oxide and 1.5-3 g urea, respectively, adding ground graphene oxide and urea to a tubular furnace, introducing argon to replace air in furnace for 2 hours, washing the surface of the sample with 1 mol hydrochloric acid several times to remove impurities, drying at 60 degrees C for 12 hours, obtaining nitrogen-doped graphene oxide, dissolving 3.5-7 mg nitrogen-doped graphene oxide powder in 10-20 mL distilled water, ultrasonically processing for 48 hours, forming a gray-brown dispersion system, removing 2.5-5 mg precipitate after 24 hours of natural sedimentation, adding 25-50 mL ethanol to the dispersion system, and ultrasonically processing for 1 hour. The mesoporous niobium pentoxide is prepared by dissolving 0.5-2 pts. wt. F127 in 10-40 pts. wt. anhydrous ethanol for 30 minutes, magnetically stirring at 500-1000 rpm, adding 2.75-11 mmol niobium pentachloride, stirring for 10 minutes, adding 0.5-1 mL 0.5 mol/L calcium chloride solution to obtained colorless and transparent solution, continuously stirring for 10 minutes, adding obtained niobium pentoxide sol to 100 mL polytetrafluoroethylene-lined autoclave, reacting at 60-70 degrees C for 5-8 days, drying obtained product, calcining at 450 degrees C for 5 hours and naturally cooled to room temperature.