Defect-induced electric field effects direct Fenton-like oxidation pathways towards polymerization for sustainable water treatment

Polymerization-oriented Fenton-like oxidation of organic pollutants offers a promising method for energy harvesting while lowering carbon emissions. However, altering the organic pollutant removal route from molecular fragmentation to polymerization is challenging. Here we report that defect engineering, i.e., tailoring defect density in carbon catalysts, can strengthen polymeric decontamination in Fenton-like oxidation reactions. Theoretical and experimental results show that the vacancy defect-induced electric field on carbon nanotubes accelerates electron transfer from 4-chlorophenol to surface-bound peroxymonosulfate, increasing the formation of polymeric precursors (i.e., phenoxonium) via the two-electron transfer route. The defects suppress the strong oxidizing species generation and enhance the precursor adsorption, simultaneously promoting the stabilization and aggregation of phenoxonium precursors for polymerization. The established oxidative system results in complete phenolic pollutant removal, with electron utilization efficiency reaching 551%. Life cycle assessment, toxicity assessments, and continuous operation tests demonstrate the system's applicability in real-world scenarios. Overall, this work provides a feasible approach to direct organic pollutant removal towards polymerization for sustainable water treatment.