No abstract

A ZnO/CdS/Cu2S composite photocatalyst with high photocatalytic activity was successfully synthesized by a three-step process. The results of XRD, XPS, SEM, and UV–Vis analysis show that ZnO nanosheets were successfully compounded with CdS nanoparticles, and the surface of CdS was successfully modified by Cu2S under ultraviolet light. Photocatalytic measurements were carried out and the results show that the photocatalytic efficiency of ZnO/CdS/Cu2S reached 95%. Compared with ZnO ([Formula: see text][Formula: see text][Formula: see text]), the kinetic constant of ZnO/CdS/Cu2S was up to [Formula: see text][Formula: see text][Formula: see text], which shows its excellent photocatalytic activity. A photocatalytic mechanism was proposed to illustrate the high activity separation efficiency.

To obtain highly efficient photocatalysts, we successfully prepared the GO/ZnO/CdS/Cu2S composite that possesses superior photocatalytic degradation performance via a three-step solvothermal process. A series of characterization techniques were used to verify the composition and performance of prepared samples, such as X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), Raman spectra, photoluminescence (PL) spectroscopy and so on. SEM reveals that copper ions are supported on the surface of CdS to form active sites for photocatalysis. Under the irradiation of ultraviolet (UV) and visible light, GO/ZnO/CdS/Cu2S photocatalyst exhibited relatively excellent photocatalytic degradation efficiency of methylene blue (MB), with 100% (80 min) and 95% (30 min), respectively. Compared with pure ZnO ([Formula: see text]) under the illumination of UV light, the kinetic constant of GO/ZnO/CdS/Cu2S catalyst is up to [Formula: see text], and as for visible light illumination, up to [Formula: see text], showing relatively excellent visible-light-induced photocatalytic activity. Besides, under UV and visible light, after three cycles of photodegradation, GO/ZnO/CdS/Cu2S still maintains the degradation efficiency of 78.3% and 74.8%, respectively, indicating that it has good stability. This work might inspire a new perspective that introduces the surface reaction sites (Cu2S) in the design of other graphene oxide/mental oxide-based heterojunctions for environmental purification.