Mesoporous TiO2-500/FeOClfev Composites for Enhanced Photo-Fenton Degradation of Sulfamethoxazole

Developing photo-Fenton catalysts that efficiently couple photogenerated charge separation with Fe redox cycling is essential for improving water treatment. Here, a TiO2-500/FeOClfev heterojunction was constructed to combine interfacial charge transfer with H2O2-assisted oxidation. The optimized 1:1 composite removed approximately 90% of sulfamethoxazole (SMX) within 10 min under simulated solar irradiation, whereas TiO2-500 and FeOCl achieved only 12.7% and 13.2% removal, respectively, under otherwise identical conditions; the NaCl-assisted FeOClfev-0.15 component achieved 81.9% removal. Structural and spectroscopic analyses indicate intimate interfacial contact, extended visible-light absorption, and interfacial electronic interactions. Enhanced photocurrent and a reduced electrochemical impedance arc further suggest more efficient charge separation and transport. Scavenger and electron spin resonance experiments identify •O2− and h+ as the dominant reactive species, with •OH also contributing. A possible direct Z-scheme pathway and Fe-mediated H2O2 activation are proposed to explain the observed behavior. These results demonstrate that coupling TiO2-500 with NaCl-assisted FeOCl is a promising strategy for improving photo-Fenton catalysis for antibiotic abatement.