[Performance and Mechanism Study of Visible Light-driven C₃N₄/BiOBr Composite Photocatalyst]

Efficient visible light-driven C₃N₄/BiOBr composite photocatalysts were prepared via a facile hydrothermal method and characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, UV-Vis diffuse reflectance spectra and photoluminescence spectra for the phase composition and optical property. Taking rhodamine B (RhB) as the target pollutant, the photocatalytic activity and stability of photocatalysts were studied under visible light irradiation. Furthermore, the mechanism in the process of photocatalytic degradation was discussed by electron spin resonance spectroscopy analysis and the trapping experiment of generated radicals. The results indicated that C₃N₄/BiOBr composite photocatalysts had excellent crystallization performance. Composited by C₃N₄, BiOBr exhibited considerably higher photocatalytic activity by reducing the rate of electron-hole recombination. Among prepared composites with various C₃N₄ contents, 15% C₃N₄/BiOBr exhibited the best efficiency for the degradation of RhB. After irradiation for 18 minutes, the degradation rate of RhB was 100%, which was 1.5 times higher than that using pure BiOBr. The results also suggested that holes and ·O₂^- were the main reactive species in the photocatalytic process for the RhB degradation, and holes played the leading role.