Low-temperature synthesis of ZnO/ZnS/CuS heterojunction based on solution-processed nanosheet array with enhanced photocatalytic activity

ZnO/ZnS/CuS net-like nanosheet (NS) heterojunction array was fabricated via a simple solution method at a low temperature. Morphology and structure of ZnO/ZnS/CuS NS were characterized by scanning electron microscope (SEM) and Transmission electron microscope (TEM). With tiny particles attaching on the rough surface, the thin ZnO/ZnS/CuS NS grew vertically and arranged regularly on Al substrate, providing large effective illumination area and massive active sites. Elemental composition and valence state were confirmed with energy dispersive X-ray spectrometry and X-ray photoelectron spectroscopy (XPS), respectively. The UV–vis absorbance spectra indicated that the absorption range of ZnO NS was expanded to the visible region effectively, and the original absorption intensity in the ultraviolet region was also improved after being coated with ZnS and CuS. Photocatalytic activity tests of ZnO, ZnO/ZnS, and ZnO/ZnS/CuS NS were carried out with methyl orange as a simulated pollutant, in which ZnO/ZnS/CuS heterojunction showed great enhancement when making comparison with pure ZnO and ZnO/ZnS NS. After five reuse cycles, photocatalytic performance could still be maintained well, indicating the good catalytic stability. Finally, a probable photocatalytic mechanism was also discussed.