Carbon-Coated Cu nanoparticles as a Cocatalyst of g-C3N4 for Enhanced Photocatalytic H2 Evolution Activity under Visible-Light Irradiation

The photocatalytic H-2 evolution is an important technology to solve the energy crisis. The hydrogen evolution rate of the graphite carbon nitride (g-C3N4) system in triethanolamine solution as sacrificial agent is clearly higher than that in methanol solution. But up to now, most of the Cu nanoparticles as cocatalyst of g-C3N4 photocatalytic systems for hydrogen evolution are performed in methanol solution because Cu nanoparticles are unstable in triethanolamine solution. Here, carbon-coated Cu nanoparticles as a cocatalyst of g-C3N4 composites (Cu@C/g-C3N4) are prepared by a simple two-step technology that includes annealing followed by grinding. The compositions, morphology, and optical and photoelectrochemical properties of the composites are characterized by means of physicochemical techniques. The prepared composition is used to generate hydrogen under visible-light irradiation in triethanolamine solution. The results show that the hydrogen evolution rate of the optimal Cu@C/g-C3N4 is up to 265.1 mu mol g(-1) h(-1), which is close to the activity of 0.5% Pt/g-C3N4, and after four repeated reactions, the photocatalytic activity decreases only by approximate to 15%. The good photocatalytic activity and stability result from Cu nanoparticles increase the transfer efficiency of charge carriers by trapping the photogenerated electrons produced by g-C3N4 and the protective effect of carbon layer on Cu nanoparticles.