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

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.