Application of ZnO/WO₃ Composite Nanofiber Photocatalysts in Textile Wastewater Treatment

Semiconductor photocatalysis technology is an environmentally friendly and efficient emerging technology. This method can use sunlight as a driving force to quickly decompose organic pollutants in water bodies. Zinc oxide (ZnO) and tungsten oxide (WO₃) photocatalysts can absorb sunlight and participate in photocatalytic degradation reactions due to their relatively narrow band gap. Highly photosensitive WO₃ nanofibers and ZnO/WO₃ composite nanofibers were fabricated via the electrospinning method. When 100 mg/L of rhodamine B (Rh B) solution was used as the degradation substrate, the degradation efficiencies of WO₃ and ZnO/WO₃ for Rh B dye were 70% and 90%, respectively, after a photocatalytic reaction of 120 min. The surface morphology, crystal structure, and optical properties of ZnO/WO₃ composite nanofibers and WO₃ nanofibers were characterized by SEM, XRD, XPS, and UV-vis absorption spectra, and the experimental results were analyzed and explained using different mechanisms. The results show that ZnO/WO₃ composite nanofibers have better UV-visible light absorption performance, and the sample has a higher UV-visible light utilization rate. This was mainly due to the fact that a P-N heterojunction was formed in the semiconductor composite, and the electron–hole pair could realize rapid separation under the drive of a built-in electric field force, which promoted the migration of carrier. Therefore, the photocatalytic activity of the ZnO/WO₃ catalyst was significantly higher than that of the WO₃ catalyst, which promoted rapid improvement of the photocatalytic degradation efficiency of the Rh B dye.