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·gcat –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 FeIII as a catalytic initiator with the CEC system enables the establishment of SC-Fenton reaction (FeIII/FEP/CEC). Notably, the contact-electrification electrons accumulated on the FEP interface drive efficient FeIII/FeII redox cycling, achieving a remarkable degradation rate for sulfadiazine at 0.125 min–1. This enhanced catalytic performance stems from FeIII-mediated amplification of dissociative hydroxyl radical (•OH) generation. This study provides fundamental insights into the underlying mechanisms of CEC-mediated FeIII-initiated SC-Fenton reaction, offering new possibilities for sustainable water purification processes.