Facile synthesis of BiOBr/Bi2WO6 heterojunction semiconductors with high visible-light-driven photocatalytic activity

• The BiOBr/Bi2WO6 heterojunction photocatalysts were successfully synthesized by the facile hydrothermal method.
• The new materials were characterized via some techniques including XRD, XPS, SEM and TEM etc.
• The photocatalytic performance of the composites were performed by degrading Rhodamine B. It comes out with high degradation efficiency and the influence of the doping amount was also explored.
• Mechanisms of the improvement in photocatalytic activity by establishing heterojunction was discussed based on the electrical structure.

Photocatalysis is a growing area of study for a clean and renewable energy source, particularly the degradation of organics in wastewater and polluted air. Researchers have studied the combination of various semiconductors to create photocatalysts with improved activities, but little has been reported in selecting semiconductors based on their extrinsic type—namely n-type or p-type. In this study, a BiOBr (p-type)-Bi2WO6 (n-type) heterojunction semiconductor was synthesized by the hydrothermal method. The new materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and diffuse-reflection spectroscopy (DRS). Their photocatalytic activities were examined by measuring the degradation rate of Rhodamine B with photocatalysts synthesized using various atomic ratios of BiOBr and Bi2WO6 (1:4, 1:1, and 4:1). These new composites’ ability to effectively degrade dye pollutants shed light on the benefits of using heterojunction photocatalysts, and also on the importance of considering the semiconductor type when forming composite photocatalysts.

The graph could be used to explain the enhancement effect of heterojunction in photocatalytic performance. Photo-generated electrons and holes could move oppositely and accumulate on conduction band of Bi2WO6 and valence band of BiOBr, respectively, which could decrease the recombination rate so as to improve the photocatalytic activity of the semiconductors.Figure optionsDownload as PowerPoint slide