Photoelectrochemical and photo-Fenton properties of ZnFe₂O₄@g-C₃N₄ nanocomposites

In the social context of increasing water pollution, we conducted an in-depth study to prepare ZnFe₂O₄@g-C₃N₄ heterojunction nanocomposites by hydrothermal method. The microscopic morphology and structure were analyzed using XRD, SEM, TEM, UV–Vis, and other characterization methods. The photo-Fenton activity of the highly concentrated antibiotic tetracycline was tested under visible light irradiation in combination with the presence of H₂O₂, and the catalytic mechanism was investigated. The results showed that the construction of heterojunction significantly improved the catalytic activity of ZnFe₂O₄@g-C₃N₄ catalyst prepared by hydrothermal method. The degradation rate of tetracycline at 40 mg L⁻¹ was 92.6% within 60 min, and the degradation rate was 0.06 min⁻¹, which was nearly six times higher than that of pure ZnFe₂O₄. The results of free radical trapping experiments and electron spin resonance technique indicated that hydroxyl radicals (·OH) and superoxide radicals (·O₂⁻) played important roles in the photo-Fenton degradation of tetracycline. Notably, the catalyst maintained a high degradation rate (87.2%) after five cycles. The heterojunction designed in this thesis may provide a promising strategy for achieving maximum light absorption and is authoritative in meeting environmental requirements in the future.