▎ 摘　　要

NOVELTY - Preparation of cobalt sulfide nanoparticles/nitrogen-doped reduced graphene oxide hydrogen evolution composite material, involves (i) dissolving cobalt(II) nitrate hexahydrate in deionized water to obtain dispersion (A), (ii) dissolving dicyandiamide in deionized water, slowly dripping dicyandiamide solution to dispersion (A), stirring evenly to obtain dispersion (B), (iii) slowly dripping graphene oxide solution into the dispersion (B), stirring, ultrasonically stirring to obtain dispersion (C), and (iv) dripping ammonia monohydrate into the dispersion (C) under vigorous stirring. USE - Preparation of cobalt sulfide nanoparticles/nitrogen-doped reduced graphene oxide hydrogen evolution composite material for use as catalyst for electrochemical hydrogen evolution (all claimed). ADVANTAGE - The preparation of cobalt sulfide nanoparticles/nitrogen-doped reduced graphene oxide hydrogen evolution composite material is simple and environmentally-friendly, and reduces cost. The composite material has excellent electro-catalytic activity and excellent hydrogen evolution stability. The introduction of hetero-atoms nitrogen into cobalt sulfide/reduced graphene oxide leads to the synergetic effect of geometrical defects so as to reduce the adsorption of carbon ions to hydrogen ions, facilitate the precipitation of hydrogen and significantly improve the electrochemical performance of cobalt sulfide. DETAILED DESCRIPTION - Preparation of cobalt sulfide nanoparticles/nitrogen-doped reduced graphene oxide hydrogen evolution composite material, involves (i) weighing a certain amount of cobalt(II) nitrate hexahydrate, dissolving in deionized water to obtain dispersion (A), (ii) weighing a certain amount of dicyandiamide, dissolving in deionized water, slowly dripping dicyandiamide solution to dispersion (A), stirring evenly to obtain dispersion (B), (iii) slowly dripping graphene oxide solution into the dispersion (B), stirring, ultrasonically stirring to obtain dispersion (C), (iv) dripping ammonia monohydrate into the dispersion (C) under vigorous stirring, adjusting the pH of solution to 10, and forming a dark green solution (D), (v) weighing certain amount of thioacetamide, dissolving in deionized water, slowly dripping the obtained solution into the dark green solution (D) under vigorous stirring condition, stirring vigorously until the reaction is complete, then transferring to a hydrothermal kettle, performing hydrothermal reaction, then cooling to room temperature, taking out, washing with deionized water and ethanol 5 times, freeze-drying to obtain black powder, (vi) transferring freeze-drying black powder to a crucible, increasing the temperature to the calcination temperature in the range of nitrogen, calcining, taking out, and grinding to obtain cobalt sulfide nanoparticles/nitrogen-doped reduced graphene oxide hydrogen evolution composite material.