BiOI/ZnO Heterojunction for Increased Photodegradation of Metronidazole under Visible Light Irradiation

A heterojunction interface with a rational design can overcome the limitation of a single photocatalyst structure and enable the separation and transport of photogenerated carriers. p-n Heterojunctions of BiOI/ZnO nano-flake were achieved by a simple one-step hydrothermal process for metronidazole (MNZ) degradation under visible light. The measurements show that the BiOI/ZnO could completely remove MNZ within 180 min, which is 2.6 times and 4.8 times higher than that of pristine ZnO and BiOI, respectively. Under visible light irradiation, the electrostatic field formed within the p-n heterojunction drives the flow of photogenerated electrons from the conduction band of BiOI to the conduction band of ZnO, while the holes are retained, promoting photogenerated carrier separation and enhancing photocatalytic efficiency. The fact that BiOI/ZnO good stability and reusability demonstrates the importance of heterostructure construction of two different semiconductors in overcoming the defects of traditional semiconductor materials.