In situ growing of CoO nanoparticles on g-C 3 N 4 composites with highly improved photocatalytic activity for hydrogen evolution.

CoO/g-C3N4 hybrid catalyst is facilely prepared for application to photocatalytic H-2 evolution from water splitting by the vacuum rotation-evaporation and in situ thermal method. The physical and chemical properties of CoO/g-C3N4 are determined by a series of characterization methods. The g-C3N4 with 0.6 wt% Co loading exhibits superior photocatalytic hydrogen evolution activity with an H-2 evolution amount of 23.25 mmol g(-1) after 5 h. The obtained 0.6 wt% CoO/g-C3N4 can split water to generate 0.39 mmol g(-1) H-2 without sacrificial agent and noble metal, while the pure g-C3N4 is inactive under the same reaction conditions. The remarkable enhancement of photocatalytic H-2 evolution activity of CoO/g-C3N4 composites is mainly ascribed to the effective separation of electron-hole pairs and charge transfer. The work creates new opportunities for the design of low-cost g-C3N4-based photocatalysts with high photocatalytic H-2 evolution activity from overall water splitting.