Nanoconfinement-mediated non-radical enhanced pollutant degradation on Fe single-atom electrocatalyst

Heterogeneous electro-Fenton (EF) technology is an efficient approach for antibiotics degradation, but the effective mineralization of pollutants in complex actual water remains challenging due to the susceptibility of hydroxyl radical (∙OH) to environmental influences. Herein, a Fe-single atom anchored porous hollow carbon sphere (Fe_xHCS) material with nano-confinement structure was designed for simultaneously catalyzing H₂O₂ to produce ∙OH and ¹O₂. Benefiting from oxidation of ∙OH and selective reaction of alkyl group with ¹O₂, the kinetic constant (k) of the Fe_xHCS-based EF system achieves 4.13 h^-1, which is 3.7 times higher than that of the traditional Fenton (1.13 h^-1) under the same conditions for ofloxacin (OFL) degradation. The mineralization efficiency of OFL by Fe_xHCS-based EF reaches 72.7 %, exceeding most of the previously reported catalysts within 1 h. The COD value of actual pharmaceutical wastewater is reduced from 801 mg L^-1 to 49 mg L^-1 after 5 h of treatment, and the energy consumption for wastewater treatment is calculated to be 15.9 kW h kg^-1 COD^-1. This work demonstrates the attractive advantages of ¹O₂ enhanced electro-Fenton performance in complex actual water and provides new insights into developing novel electrocatalysts for wastewater treatment.