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

Polymerization-oriented Fenton-like oxidation process offers a promising way for energy harvesting while lowering carbon emissions. However, altering the pollutant removal route from molecular fragmentation to polymerization remains challenging. Here we report that defect engineering, i.e., tailoring defect density in carbon catalysts, can strengthen the polymeric decontamination process in Fenton-like oxidation reactions. Theoretical and experimental results show that the vacancy defect-induced build-in electric field on carbon nanotube accelerate electron transfer from 4-chlorophenol to surface-bound PMS, boosting the formation of polymeric precursors (i.e., phenoxonium) via two-electron transfer route. The defects simultaneously enhance the adsorption of the generated precursors on the catalysts with strengthened binding interactions, further promoting the stabilization, and aggregation of phenoxonium precursors for polymerization. The established oxidative systems achieved complete phenolic pollutant removal with electron utilization efficiency reaching 551%. The carbon emission was also reduced by 74% relative to the complete mineralization strategy. Overall, this work provides a novel feasible approach to direct organic pollutant removal towards polymerization with low carbon emission for sustainable water treatment.