Enhanced photocatalytic performance of porous ZnO thin films by CuO nanoparticles surface modification

Improving the response of ZnO photocatalyst to visible light is a hot topic. In this work, the porous ZnO thin films were first prepared by sol-gel method, and then CuO nanoparticles were deposited on the porous ZnO thin films to form CuO-ZnO heterojunction; the effect of CuO content on the photocatalytic activity of ZnO thin films were investigated. The results show that the formation of CuO-ZnO heterojunction effectively separates the photogenerated electron-hole pairs, leading to significant decrease of ZnO ultraviolet emission. In addition, the ZnO thin films with CuO nanoparticles modified on the surface increase the absorptive capacity in the visible range. Photocatalytic degradation of methylene blue shows that the photocatalytic activity of all CuO/ZnO thin films is greatly improved. The improvement of photocatalytic performance should be attributed to the enhanced separation efficiency of photogenerated electron-hole pairs by the CuO-ZnO heterojunction and the increased light absorption in the visible range by CuO nanoparticles. This kind of CuO/ZnO thin films also shows good photocatalytic reusability.