CdS nanospheres hybridized with graphitic C3N4 for effective photocatalytic hydrogen generation under visible light irradiation

Graphitic carbon nitride (g-C3N4)-based photocatalysts have received considerable attention in the field of photocatalysis, especially for photocatalytic H-2 evolution. However, the intrinsic disadvantages of g-C3N4 seriously limit its practical application. Herein, CdS nanospheres with an average diameter of 135 nm prepared using a solvothermal method were used as co-catalysts to form CdS/g-C3N4 composites (CSCN) to enhance the photocatalytic activity. Various techniques were employed to characterize the structure, composition and optical properties of the as-prepared samples. It was found that the CdS nanospheres were relatively uniformly dispersed on the surface of g-C3N4. Moreover, the photocatalytic H-2 generation activity of the samples was evaluated using lactic acid as sacrificial reagent in water under visible light irradiation. When the amount of CdS nanospheres loaded in the hybridized composites was 5 wt%, the optimal H-2 evolution rate reached 924 mu mol g(-1) h(-1), which was approximately 1.4 times higher than that (680 mu mol g(-1) h(-1)) of Pt/g-C3N4 (3 wt%). Based on the results of analysis, a possible mechanism for the photocatalytic activity of CSCN is proposed tentatively.