Study on FeS2/g-C3N4 as a photo-Fenton heterojunction catalyst for tetracycline degradation with H2O2 under visible light irradiation

Abstract Background Heterojunction catalysts have been used in photo-Fenton reaction. However, the rapid recombination of photo-generated electron-hole would reduce the reaction and decrease the organic degradation rate. Methods In order to improve the photocatalytic performance of g-C3N4 and the dispersion of FeS2 in solution, FeS2/g-C3N4 with Schottky junction was prepared by introducing FeS2 to g-C3N4. The hybridized FeS2/g-C3N4 heterojunction was thoroughly characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), photocurrent and photoluminescence (PL) emission. The ratio of FeS2 and g-C3N4 in the material was optimized on the photocatalytic performance. Meanwhile, the photocatalytic activity was evaluated in the removal of tetracycline (TC) under visible light. Furthermore, the reactive species were identified through quenching tests and a possible mechanism of the reaction was put forward. Degradation pathway of TC was proposed and toxicity assessment of intermediates were conducted. Significant findings The 20% FeS2/g-C3N4 sample showed the most effective and economical photocatalytic efficiency. The TC degradation was apparently enhanced in FeS2/g-C3N4/H2O2 system comparing with FeS2/H2O2 or g-C3N4/H2O2. Results showed that FeS2/g-C3N4 was a steady catalyst through investigating the effect of environment parameters and composite recyclability.