Synthesis of novel Cu2WS4/Bi2WO6 heterojunctions and evaluation of their photocatalytic activity for removal of tetracycline under visible light irradiation

In order to change the photocatalytic performance of bismuth tungstate monomer material, the Z-type heterojunction Cu2WS4/Bi2WO6 (CWS/BW) system was formed by loading Cu2WS4 on Bismuth tungstate by hydrothermal method, and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It was concluded that the crystallinity of Cu2WS4/Bi2WO6 system varied with the change of the composite ratio, and no impurity influence was found. The morphology of Cu2WS4/Bi2WO6 system reflects the flower bulbous formed by the superposition of Cu2WS4 nanosheets and Bi2WO6 nanosheets. The overall analysis shows that Cu2WS4 and Bi2WO6 were successfully compounded. Through the characterization analysis of ultraviolet-visible diffuse reflectance absorption spectra (UV-Vis DRS), photoluminescence spectrogram (PL) and N2 adsorption-desorption isotherm analysis (BET), it was concluded that the Cu2WS4/Bi2WO6 system had a higher specific surface area, a wider light corresponding range and a lower photogenerated electron-hole recombination rate. Experiments show that the 5-CWS/BW in the Cu2WS4/Bi2WO6 system had the strongest photocatalytic effect under visible light, and the light degradation rate in 100min can reach 80%, which is 1.7 times and 3.2 times that of monomer Bi2WO6 and Cu2WS4, respectively. 5-CWS/BW still had high activity under different experimental conditions. Later, cyclic experiments proved that the material had strong stability. Finally, the main active substances in photocatalysis were clarified through free radical capture experiments and electron spin resonance (ESR) technology, and the photocatalytic mechanism of Cu2WS4/Bi2WO6 system was inferred.