▎ 摘　　要

NOVELTY - A cobalt sulfide/nitrogen-doped graphene composite material preparing method involves dispersing activated graphene oxide. Nitrogen-doped graphene is prepared. Cobalt sulfide/nitrogen-doped graphene is prepared by weighing nitrogen-doped graphene powder in mixed solution of secondary water and ethanol, ultrasonic dispersion evenly after adding cobalt acetate and thiourea heptahydrate, continue to ultrasonic and stirring, after the solution is transferred to reactor, washing resulting precipitate with secondary water and ethanol and centrifuging, drying by vacuum to obtain composite material. USE - Method for preparing cobalt sulfide/nitrogen-doped graphene composite material for construction of electrochemical sensors in electrochemical analysis of hydrogen peroxide (claimed). ADVANTAGE - The composite material has large specific surface area, high conductivity and strong biocompatibility nitrogen doping and electrochemical reduction of hydrogen peroxide, strong catalytic effect, wide detection range, low detection limit, high sensitivity and selectivity. DETAILED DESCRIPTION - A cobalt sulfide/nitrogen-doped graphene composite material preparing method involves dispersing activated graphene oxide by weighing 30-80 mg oxidized graphite, dispersing in distilled water and ultrasonically dispersing for 2-5 hours. Nitrogen-doped graphene is prepared by adjusting pH of the graphene dispersion to 9-11 by using ammonia water, adding 0.8-1.6 ml hydrazine hydrate, at reaction temperature of 40-60 degrees C for 18- 36 hours after which the product is centrifuged and washed and dried to produce nitrogen-doped graphene powder after vacuum drying. Cobalt sulfide/nitrogen-doped graphene is prepared by weighing nitrogen-doped graphene powder in the mixed solution of secondary water and ethanol, ultrasonic dispersion evenly after adding cobalt acetate and thiourea heptahydrate, continue to ultrasonic and stirring to make it all dissolved, after the solution is transferred to the reactor for hydrothermal reaction at 150-170 degrees C for 20-30 hours, after the end of the reaction, washing resulting precipitate with secondary water and ethanol and centrifuging, finally drying by vacuum to obtain cobalt sulfide/nitrogen-doped graphene composite material, where the ratio of secondary water to ethanol is 1- 1.5:1, the mass ratio of nitrogen-doped graphene, cobalt acetate and hydrazine tetrahydrate is 1: 35-45: 10-20.