Heterogeneous photo-Fenton system of novel ternary Bi2WO6/BiFeO3/g-C3N4 heterojunctions for highly efficient degrading persistent organic pollutants in wastewater

Abstract In this study, novel ternary Bi2WO6/BiFeO3/g-C3N heterojunctions with enhanced photocatalytic activity were synthesized and its heterogeneous photo-Fenton system was construct for highly effectively degrading persistent organic wastes, namely rhodamine B (RhB) and tetracycline hydrochloride (TH). Furthermore, the mechanism of generated free radicals in this heterogeneous photo-Fenton system was explored. The characteristics of the as-prepared photocatalysts were investigated in detail by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectra (FT-IR), UV–vis diffuse reflectance spectra (UV-DRS), Photoluminescence spectra (PL), Electrochemical Impedance Spectroscopy (EIS) and Mott-Schottky curves. The results demonstrated that the heterojunction between Bi2WO6, BiFeO3 and g-C3N has formed, which can narrow the band gap to improve separation and migration of photogenerated electrons-hole pairs. In addition, it has been suggested that the recombination of photogenerated electron-holes can be inhibited due to the good conductivity of BiFeO3 and g-C3N4. Hence, Bi2WO6/BiFeO3/g-C3N possessed enhanced photocatalytic activity, which can further enhance photo-Fenton activity to effectively degrade RhB (99.85 % in 30 min) and TH (83.68 % in 45 min). In addition, it has been determined that Bi2WO6/BiFeO3/g-C3N mainly produce O2− and e+ played the main roles in the photo-Fenton activity, rather than OH−. This study not only confirmed the feasibility of heterogeneous photo-Fenton system of Bi2WO6/BiFeO3/g-C3N4 for highly efficient degradation of persistent organic pollutants in wastewater, but also provided a mothed to synthesized the novel heterojunction of Bi2WO6/BiFeO3/g-C3N4 with enhanced photocatalytic activity.