Construction of a Bi₂WO₆/TiO₂ heterojunction and its photocatalytic degradation performance

TiO₂ was prepared via a solvothermal method, and a Bi₂WO₆/TiO₂ heterojunction was constructed via a hydrothermal method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the crystal structure and morphology of composite photocatalysts with different molar ratios. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) were used to analyze the elemental composition and chemical state of the photocatalysts. We explored the degradation performance of the photocatalysts toward rhodamine B (RhB) and tetracycline (TC). When the molar ratio of TiO₂ to Bi₂WO₆ is 6, the composite photocatalyst has the best degradation performance. Under visible light irradiation for 20 min and 25 min, the degradation rates of RhB and TC were 96% and 78%, respectively. The PL and photocurrent results show that the combination of TiO₂ and Bi₂WO₆ can significantly improve the photogenerated carrier separation efficiency of the composite photocatalyst. The main active species in the photocatalytic degradation process is h⁺, as h⁺ can not only directly degrade pollutants, but also undergo redox reactions with OH⁻ to generate ˙OH, which participates in the degradation of organic pollutants.