FeIII-driven self-cycled Fenton via contact-electro-catalysis for water purification

Abstract

While self-cycled Fenton (SC-Fenton) systems represent an innovative advancement in water purification technologies, their practical implementation remains constrained by inefficient in situ H₂O₂ generation. To address this limitation, we developed a mechano-driven contact-electro-catalysis (CEC) platform employing fluorinated ethylene propylene (FEP) as a triboelectric catalyst. Under ultrasound irradiation, this system achieves an exceptional H₂O₂ generation rate of 7.67 mmol·g_cat^–1·h^–1, outperforming conventional piezo-catalysis systems. Mechanistic studies reveal that a built interfacial electric field generated on the FEP surface effectively reduces the free energy for the indirect 2e^– water oxidation pathway. This unique characteristic promotes the generation of interfacial hydroxyl radical (^*OH) and enhances its subsequent recombination into H₂O₂. The strategic integration of Fe^III as a catalytic initiator with the CEC system enables the establishment of SC-Fenton reaction (Fe^III/FEP/CEC). Notably, the contact-electrification electrons accumulated on the FEP interface drive efficient Fe^III/Fe^II redox cycling, achieving a remarkable degradation rate for sulfadiazine at 0.125 min^–1. This enhanced catalytic performance stems from Fe^III-mediated amplification of dissociative hydroxyl radical (^•OH) generation. This study provides fundamental insights into the underlying mechanisms of CEC-mediated Fe^III-initiated SC-Fenton reaction, offering new possibilities for sustainable water purification processes.