Fabrication of ternary reduced graphene oxide/SnS/ZnFeO composite for high visible-light photocatalytic activity and stability.

Metal sulfides are promising photocatalysts for efficient removal of organic pollutants in wastewater. However, the practical application of these catalysts is limited due to the fast recombination of charge carriers and poor catalyst stability. In this study, ternary reduced graphene oxide/SnS/ZnFeO (rGO/SnS/ZnFeO) composites were synthesized by a hydrothermal process, and rGO content was optimized. The surface morphology, crystal structure, optical and electrochemical properties of rGO/SnS/ZnFeO composites were characterized. The adsorption capacity and visible-light photocatalytic activity of rGO/SnS/ZnFeO were influenced by rGO content with results revealing an optimal rGO content of 7wt.%. The 7% rGO/SnS/ZnFeO composite demonstrated the highest visible-light photocatalytic activity with almost 100% 2-nitrophenol removal, which could be attributed to the efficient charge separation, and the formation of O, h and a few OH radicals. The possible photocatalytic mechanism of rGO/SnS/ZnFeO composites was also provided based on the role of rGO and the energy bands of SnS and ZnFeO. Moreover, rGO/SnS/ZnFeO composites exhibit excellent reusability without an obvious decline in the photocatalytic activity after four degradation-regeneration cycles. The results indicate that ternary rGO/SnS/ZnFeO composites have good prospect in practical removal of organic pollutants in wastewater due to high efficiency and excellent stability.