Design of visible-light-responsive O-doped graphitic carbon nitrides with tailored band structures for enhanced photo-fenton degradation of sulfathiazole

The combination of photocatalytic technology and advanced oxidation technology is a promising strategy for degrading recalcitrant antibiotic contaminants. In this study, a novel hybrid Photocatalysis-Self-Fenton (PSF) system that combines photocatalysis with the Fenton reaction was designed and used for sulfamethazine (SMR) antibiotics degradation. Firstly, a highly active oxygen-doped carbon nitride (CNO) nanosheet photocatalyst was synthesized using a simple and environmentally friendly approach. The prepared CNO nanosheets demonstrated increased exposure of active sites and improved separation of photoinduced electron-hole pairs, thus achieving a remarkable H 2 O 2 production rate of 863.8 μmol g −1 under visible light. Under the synergistic effect of a “photo-Fenton cycle” with Fe (II)，the CNO-based PSF system achieved efficient and stable removal of sulfathiazole (STZ) without external hydrogen peroxide addition. Consequently, the degradation efficiency of STZ under visible light increased significantly from 54.8 % to 98.2 % within 60 min, far exceeding the performance of pristine photocatalysts. This approach overcomes the limitations of traditional Fenton oxidation by enabling in-situ production and utilization of H 2 O 2 , and provides valuable insights into the design of photocatalytic self-Fenton processes for wastewater treatment.