Fluorocarbon polymers mediated contact-electro-catalysis activating peroxymonosulfate for emerging pollutants degradation: The key role of fluorine density in electron transfer

Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been extensively investigated for environmental pollutants remediation. Moreover, systematic exploration of catalysts with the high-efficient, cost-effective, and environment-durable properties has been usually recognized as the crucial pathway to boost PMS activation and enhance pollutants degradation. Herein, we demonstrated that the inert fluorocarbon polymers (FCPs) mediated contact-electro-catalysis (CEC) under ultrasound can be utilized to activate PMS (FCPs/PMS/US) for high-efficient degradation and detoxication of emerging pollutants (EPs). The catalytic EPs degradation process was dominant with ¹O₂ pathway, accompanied by radical pathways (^•OH, SO₄^•−, and O₂^•−). Density functional theory calculations and correlation analysis provided strong evidence for the fluorine (–F) density-dependent electron transfer among H₂O-FCPs-electron acceptors, which determined the generation of reactive oxidative species and EPs degradation rate in FCPs/PMS/US. Consequently, fluorinated ethylene propylene (FEP) with the highest –F density exhibited higher degradation rate of sulfadiazine (k_obs = 0.043 min⁻¹, at an FEP dosage of 0.25 g·L⁻¹) compared to polytetrafluoroethylene and polyvinylidene fluoride. Besides, the FCPs/PMS/US system showed excellent stability, durability, and promising applicability for high-salinity seawater remediation, with the electrical energy per log order of 0.53 kWh·m⁻³. This study provided a novel route for PMS activation and stimulates further exploration of CEC for environmental remediation.