Photocatalytic study of metal oxide enhanced ZnO synthesized by a one-step cyclic-microwave method: The role of the p-n heterostructure

Abstract

In this work, the role of the p-n junction in the photocatalytic degradation of various dyes in contaminated wastewater was studied. The n-type ZnO was synthesized by the cyclic-microwave method and was enhanced by various metal oxides, e.g., CuO, NiO, and Fe2O3. The materials were characterized by various methods. The degradation of Methylene blue (MB), Methyl orange (MO), and Rhodamine B (RhB) under the photocatalysts and UV light irradiation was examined. From the results, the performance of the dye degradation by the p-n CuO/ZnO and NiO/ZnO materials was better than that of the pure ZnO. On the other hand, the n-n heterostructure Fe2O3/ZnO showed a decrease in photocatalytic performance. The photocatalyst with the highest performance was Ni(5)-ZnO, which can degrade dyes contaminating water by greater than 99.71%. The physical principle behind the increase in the photocatalytic performance is due to the formation of the p-n junction by CuO and NiO to the n-type ZnO, resulting in the efficient generation of electron-hole pairs.