Enhanced electrochemical-activation of HO to produce •OH by regulating the adsorption of HO on nitrogen-doped porous carbon for organic pollutants removal.

The heterogeneous Fenton oxidation is regarded as a promising technology for refractory organic pollutants removal relying on highly active •OH generated via the decomposition of HO catalyzed by iron-based catalyst that overcomes the issues of pH limitation and iron sludge discharge encountered in conventional Fenton reaction. However, the efficiency of •OH production in heterogeneous Fenton remains low as the limited mass transfer between HO and catalysts caused by the poor HO adsorption. Here, a nitrogen-doped porous carbon (NPC) catalyst with tunable N configuration was prepared for electrochemical-activation of HO to •OH by enhancing the HO adsorption on catalysts. The resultant •OH production yield on NPC reached 0.83 mM in 120 min. Notably, the NPC catalyst could be more energy-efficient for actual coking wastewater treatment with an energy consumption of 10.3 kWh kg than other electro-Fenton catalysts reported (20-29.7 kWh kg). Density function theory (DFT) revealed that highly efficient •OH production was ascribed to the graphitic N which enhances the adsorption energy of HO on NPC catalyst. This study provides new insight into the fabrication of efficient carbonaceous catalysts by rationally modulating electronic structures for refractory organic pollutants degradation.