Performance and mechanism of double S-scheme FeOOH/TiO2/g-C3N4 heterojunction for acetochlor degradation under visible-light-driven photo-Fenton.

A novel FeOOH/TiO2/g-C3N4 (FTCN) dual S-scheme heterojunction catalyst was synthesized via hydrothermal assembly and comprehensively characterized. The catalytic performance of various systems was evaluated through acetochlor (ACT) degradation experiments, which revealed the FTCN/Visible-Light Photo-Fenton system as the optimal configuration. Under controlled conditions ([ACT] = 10 mg L-1, FTCN = 100 mg L-1, H2O2 = 5 mmol L-1, pH 7, light intensity = 2300 W m-2), the system achieved 100 % ACT degradation within 20 min with an apparent rate constant of 0.252 min-1. FTCN catalyst exhibited exceptional reusability and structural integrity across four consecutive photo-Fenton cycles, effectively reducing energy consumption while more closely resembling the actual use of sunlight. Radical scavenging assays and electron paramagnetic resonance (EPR) spectroscopy conclusively identified four reactive species in the FTCN/photo-Fenton system: e-, h, ·O2-, and ·OH, with ·OH being the predominant oxidative agent.