Interfacial capture and electro-Fenton degradation of polyethylene microplastics using a dual-function ferrocene-MOF electrode

Polyethylene (PE) microplastics are chemically inert, environmentally persistent, and difficult to remove or oxidize using conventional separation-based treatment processes. Here, we report an in situ capture–electro-Fenton degradation strategy that integrates microplastic enrichment and oxidative conversion within a dual-function ferrocene-based MOF electrode (ER-Fc-MOF@NiF). The electrode provides abundant interfacial binding sites that locally accumulate PE on the catalytic surface, enhancing the contact efficiency between reactive oxygen species and polymer chains during electro-Fenton operation. The electrode exhibits a high adsorption capacity of 150.8 mg·g −1 toward PE microplastics and enables progressive oxidative fragmentation of the polymer within 36 h under electro-Fenton conditions. Structural and spectroscopic analyses (SEM, XPS, TOC, and EDS) reveal the formation of oxygen-containing functionalities and surface erosion of the polymer. Electron paramagnetic resonance (EPR) measurements confirm the generation of •OH and 1 O 2 , indicating a cooperative radical/non-radical oxidation pathway. By integrating capture and oxidation within a single electrode, the system forms an interfacial capture–conversion microzone where microplastics are retained and subsequently undergo interfacial oxidative transformation and fragmentation. The ER-Fc-MOF@NiF electrode maintains stable adsorption performance across a wide pH range, tolerates common inorganic ions, and remains effective in real water matrices. This work provides a compact capture-to-degradation platform with practical potential for microplastic remediation and offers a transferable strategy for the treatment of other polymeric micropollutants.