Particle size-dependent structure-activity relationship governing radical and electron-transfer pathways in...

The pervasive occurrence of emerging contaminants, particularly antibiotics, in aquatic environments poses significant threats to ecological integrity and human health. Although peroxymonosulfate (PMS) -driven advanced oxidation processes (PMS-AOPs) represent a promising strategy for pollutant abatement, the role of catalyst particle size governing the oxidation pathways, particularly in metal-free carbon-based catalysts, remains unclear. Herein, a series of structurally well-defined metal-free carbon-based catalysts were synthesized via silica-templating to investigate their size-dependent effects on PMS activation mechanisms. Our findings reveal that the electron transfer pathway (ETP) is the dominant mechanism in the catalytic system, collectively governed by particle size and surface functionality. Conversely, the radical pathway demonstrates a distinct size dependence, with its contribution increasing proportionally to particle size. Notably, the 0.1-SS (0.1 μm silica-templated sphere) catalyst exhibited superior degradation performance for electron-donating contaminants, along with excellent interference resistance and environmental friendliness as evidenced by continuous-flow experiments and life cycle assessment (LCA). Phytotoxicity assays confirmed that the treated water exhibited mitigated harmful effects, demonstrating its potential for practical application. This study elucidates the pivotal role of particle size in regulating oxidative pathways in carbon-based catalysts, thereby providing valuable insights for developing efficient catalytic water treatment systems.