Binder-free WS2/ZrO2 hybrid as a photocatalyst for organic pollutant degradation under UV/simulated sunlight and tests for H2 evolution

Novel photocatalysts based on sunlight-driven active two-dimensional (2D) layered materials have drawn considerable attention because of their structural-to-photoactive properties. In this study, via binder-free electrostatic self-assembly, WS2/ZrO2 hybrids were synthesized using a two-step hydrothermal process. The catalysts were thoroughly examined using different analysis techniques. The results indicated that in the WS2/ZrO2 hybrids, ZrO2 nanoparticles (NPs) were randomly grafted on the planar surfaces of WS2 nanosheets (the ZrO2 NPs were tightly anchored to the nanosheets). The WS2/ZrO2 hybrids could considerably enhance the photocatalytic reactions under ultraviolet (UV) and simulated sunlight irradiation with an increase in the amount of ZrO2 NPs anchored to WS2 nanosheets, which influenced the photodegradation rate of crystal violet (CV) dye and the H-2 evolution activity. Notably, the rate of H-2 generation via the photolysis of water was 1023.9 mu mol g(-1) h(-1) for the WS2/ZrO2-2 catalyst, indicating both the enhanced photocatalytic degradation activity and the H-2 advancement performance of the WS2/ZrO2 hybrid. The photocatalytic H-2 advancement rate for the WS2/ZrO2-2 catalyst was 5.28 and 1.49 times higher than those for the bare WS2 catalyst under UV and simulated solar illumination, respectively. Additionally, the WS2/ZrO2-2 hybrid exhibited high recyclability owing to the highly hydrophobic nature of the 2D WS2, which was beneficial for the separation of the hybrid photocatalyst from the CV solution. Finally, the results of a scavenger-trapping experiment indicated that active holes (h(+)) were mainly responsible for the photocatalytic reaction, rather than O-center dot(2)- and (OH-)-O-center dot. Plausible photoreaction mechanisms of photocatalytic degradation and H-2 production in aqueous solutions of the WS2/ZrO2 hybrid were elucidated. (C) 2019 Elsevier B.V. All rights reserved.