Synthesis and activity evaluation of p-n CuO/CeO2-ZrO2 heterojunction photocatalyst for the removal of dye from industrial wastewater under Visible light irradiation

In this study, p-n junction photocatalyst CuO/CeO2ZrO2 with different concentrations of CuO was prepared by auto solution combustion method using glycine as fuel. This method is simple, fast and cost effective compared with other preparation methods. The photocatalyst was characterized by X-ray diffraction (XRD), energy-dispersive spectrometer (EDS), UV-vis DRS. The assembly of p-type CuO nanoparticles produces a large number of nano p–n junction heterostructures on the surface of the CeO2ZrO2 nanocrystals, where CuO and CeO2ZrO2 form p- and n-type semiconductors. The experimental results reveal that p–n junction CuO/CeO2-ZrO2 heterojunction nanostructures exhibit much higher visible-light photocatalytic activities than the n-CeO2-ZrO2 for the removal of dye from industerial waste water. The photocatalytic activity of the p-n CuO/CeO2-ZrO2 heterojunction photocatalyst was evaluated using the degradation of aqueous methylene blue solution (MB) under visible light irradiation(λ>420 nm). The photo-degradation rate of this catalyzed is much faster than those occurring on n-type CeO2ZrO2. The sample with a p-n CuO/ CeO2-ZrO2 molar ratio of 0.021 presented the best photocatalytic activity, which was 30% higher than that of n-type CeO2ZrO2. The heat treatment condition also influences the photocatalytic activity strongly, and the best preparation condition is about 400ºC for 4h.