Surface Decoration of ZnWO(4) Nanorods with Cu(2)O Nanoparticles to Build Heterostructure with Enhanced Photocatalysis

The surface of ZnWO(4) nanorods was decorated with Cu(2)O nanoparticles (Cu(2)O/ZnWO(4)) prepared through a precipitation method. The Cu(2)O nanoparticles were tightly deposited on the ZnWO(4) surface and had average diameters of 20 nm. The nanoparticles not only promoted the absorption and utilization of visible light but also facilitated the separation of photogenerated charge carriers. This brought an improvement of the photocatalytic activity. The 5 wt % Cu(2)O/ZnWO(4) photocatalyst displayed the highest degrade efficiency for methylene blue (MB) degradation under visible light, which was 7.8 and 2 times higher than pure ZnWO(4) and Cu(2)O, respectively. Meanwhile, the Cu(2)O/ZnWO(4) composite photocatalyst was able to go through phenol degradation under visible light. The results of photoluminescence (PL), photocurrent, and electrochemical impedance spectra (EIS) measurements were consistent and prove the rapid separation of charge, which originated from the match level structure and the close contact with the interface. The radical and hole trapping experiments were carried out to detect the main active substances in the photodegradation process. The holes and ·O(2)(−) radicals were predicted to dominate the photocatalytic process. Based on the characterization analysis and experiment results, a possible photocatalytic mechanism for enhancing photocatalytic activity was proposed.