Photoswitching-Modulated Interfacial Electron Transfer in Single-Atom Co-TiO2 for Enhanced Pollutant Mineralization in Persulfate-Based AOPs

Precise modulation of interfacial electron transfer in heterogeneous catalysts is crucial for efficient degradation of persistent organic pollutants in persulfate-based advanced oxidation processes. In this work, we introduced a photoswitching strategy that in situ regulates electron transfer in single-atom Co–TiO2 catalysts, optimizing the production of reactive oxidative species during peroxymonosulfate (PMS) activation, thereby improving pollutant mineralization efficiency. Theoretical calculations revealed that the formation of high-valent Co-oxo species during PMS activation was thermodynamically favorable. By modulating photogenerated electron flow, the process dynamically shifted between nonradical and radical pathways. A dark–light interval system derived from this photoswitching approach significantly improved contaminant removal, with bisphenol A mineralization efficiency increasing from 29.50% in the dark and 47.81% under continuous light to 62.62% with the interval system. Similar improvements were observed in the treatment of practical coking wastewater. This study proposes a novel light-modulated PMS activation strategy that offers a promising solution for advanced pollutant degradation and sustainable wastewater treatment.