Single-atom cobalt tailoring the built-in electric field in g-C3N4/TiO2 for enhanced photo-assisted Peroxymonosulfate activation

The combination of peroxymonosulfate (PMS) activation and photocatalytic process was an ideal approach for removing persistent organic pollutants. Here, we constructed a single-atom Co-modified S-scheme heterojunction (0.5CoCN/TiO 2 ) to achieve efficient photoexcitation synergistic PMS activation. Comprehensive characterization and theoretical calculation verified that the addition of Co atoms could strengthening the built-in electric field (BIEF) in heterojunction, which accelerates the rearrangement of Co(III)/Co(II). Meanwhile, the Co atoms bonded with the O in PMS accelerate the adsorption of PMS and facilitate the migration of photoexcitation electrons from CoCN to PMS, thereby boosting the generation of reactive oxygen species (ROS). Furthermore, Co atoms optimized the configuration of active sites, facilitating the simultaneous occurrence of non-radical pathways. Driven by the synergistic effects of Fenton-like reactions and photocatalytic reactions, the optimal heterojunction delivered outstanding catalytic activity, degrading 97.2% of sulfadiazine at a low PMS concentration. This research provides a novel strategy to promote the removal of environmentally persistent pollutants via photo-assisted PMS activation.