Construction of Z-scheme C-LaFeO3/Co-doped g-C3N4 heterojunction for synergistic photocatalysis-PMS activation in antibiotic degradation

Advanced oxidation processes (AOPs) based on photocatalysis and peroxymonosulfate (PMS) activation hold great promise for the remediation of organic wastewater. To overcome the limitation of narrow light utilization, sluggish PMS activation, and weak synergy between photocatalysis and PMS activation, the rational integration of transition-metal-mediated PMS activation with heterostructure engineering under light provides an efficient pathway for accelerating internal electric field construction and enhancing pollutant degradation. Herein, a C-LaFeO 3 anchored Co-doped g-C 3 N 4 (C-LFO/Co-CN) catalyst was synthesized via a multi-step in situ calcination strategy. When the mass ratio of C-LFO: Co: CN was optimized to 10:1:100, the C-LFO/Co-CN catalyst exhibited optimal photo-Fenton-like synergistic performance, achieving an initial 30-minute degradation rate 5.8 times higher than that under visible light alone. It was revealed that the Co sites directly interact with PMS to form high-valent cobalt (Co(IV) = O). Furthermore, the reconstruction of the internal electric field establishes a Z -scheme heterojunction. This configuration drives the directional migration of photogenerated electrons under illumination, promoting the direct involvement of photogenerated holes from the C-LFO valence band in the degradation of NOR. The influx of photogenerated electrons in Co-CN facilitates the reduction of Co valence states, while in C-LFO, the Fe sites further participate in the formation of a Co Fe valence state cycling system under the activation of PMS. These synergistic dual-metal redox cycles ultimately promote the highly efficient degradation of NOR in the (C-LFO/Co-CN)-PMS-Vis system. This study provides new mechanistic insights and theoretical guidance for efficient photocatalysis–PMS synergistic catalysts for wastewater treatment.