▎ 摘　　要

NOVELTY - A catalyst comprises tricobalt tetroxide, graphite phase carbonitride and graphene oxide. USE - The catalyst is useful for treating pollutants such as hexavalent chromium and methyl blue in sewage (claimed). ADVANTAGE - The catalyst has excellent adsorption and photocatalytic dual function. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a process for preparing the catalyst, which involves (1) preparing graphene oxide by dispersing a graphite material in 98 %mass concentrated sulfuric acid, adding sodium nitrate under the condition of maintaining the temperature at below 10 degrees C, adding potassium permanganate under magnetic stirring conditions, reacting for 3-5 hours, heating at 30-35 degrees C after the reaction is completed, reacting for 30-60 minutes, diluting the reaction mixture with distilled water, again heating at 70-90 degrees C for 10-30 minutes, then diluting with water, leaving still for 2-8 minutes, cooling to 20-30 degrees C, adding hydrogen peroxide until the color became golden yellow, then separating the solid phase by centrifugation, washing the solid phase with 5% hydrochloric acid and ethanol, respectively and freeze-drying, and (2) preparing Cobalt tetroxide-graphitic carbon nitride-graphene oxide by (a) weighing graphene oxide, graphitic carbon nitride powder, N,N-2-methylpyrrolidone, acetic acid, cetyltrimethylammonium bromide, cobalt nitrate and thiourea, where the mass ratio of graphene oxide to graphitic carbon nitride powder is 1:(0.15-0.6), the mass ratio of graphene oxide to the volume of the N,N-2-methylpyrrolidone is 1 g:(300-400) ml, the mass ratio of graphene oxide to the volume of acetic acid is 1 g:(40-80) ml, the mass ratio of graphene oxide to cetyltrimethylammonium bromide is 1:(1-2), the mass ratio of graphene oxide to cobalt nitrate is 1:(10-20), and the mass ratio of graphene oxide to thiourea is 1:(6-12), (b) dispersing the graphene oxide in deionized water to obtain a graphene oxide dispersion, (c) dispersing the graphitic carbon nitride in deionized water to obtain a graphitic carbon nitride dispersion, (d) adding cetyltrimethylammonium bromide to ionic water to prepare a cetyltrimethylammonium bromide solution, (e) ultrasonically mixing the graphene oxide dispersion, the carbon nitride dispersion and the N,N-2-methylpyrrolidone for 2-4 hours to obtain a mixed solution, adding acetic acid to the mixed solution, stirring for 3-5 minutes, then adding the cetyltrimethylammonium bromide solution under stirring for 10-12 hours, finally adding cobalt nitrate and thiourea and stirring for 0.5-1 hour to obtain a precursor liquid, and (f) adding the precursor solution to a reaction kettle, placing the kettle in a blast oven at 180-200 degrees C for 24-28 hours, cooling to room temperature, separating the solid phase, followed by washing with deionized water and ethanol, respectively and then freeze-drying; and (2) use of the catalyst for treating pollutants such as hexavalent chromium and methyl blue in sewage, which involves adjusting the pH of the sewage to-be-treated containing hexavalent chromium and methyl blue to 2-6, adding 0.5-1 g catalyst to per 1 l sewage to-be-treated, and irradiating by a natural light or a xenon lamp source for 2-3 hours to complete the treatment of sewage containing hexavalent chromium and methyl blue by adsorption and photocatalysis.