Regulating the Electronic Structure of Cu Single-Atom Catalysts toward Enhanced Electro-Fenton Degradation of Organic Contaminants via 1O2 and •OH

Abstract

Heterogeneous electro-Fenton degradation with ¹O₂ and ^•OH generated from O₂ reduction is cost-effective for the removal of refractory organic pollutants from wastewater. As ¹O₂ is more tolerant to background constituents such as salt ions and a high pH value than ^•OH, tuning the production of ¹O₂ and ^•OH is important for efficient electro-Fenton degradation. However, it remains a great challenge to selectively produce ¹O₂ and improve the species yield. Herein, the electronic structure of atomically dispersed Cu–N₄ sites was regulated by doping electron-deficient B into porous hollow carbon microspheres (CuBN-HCMs), which improved *O₂ adsorption and significantly enhanced ¹O₂ selectivity in electro-Fenton degradation. Its ¹O₂ yield was 2.3 times higher than that of a Cu single-atom catalyst without B doping. Meanwhile, ^•OH was simultaneously generated as a minor species. The CuBN-HCMs were efficient for the electro-Fenton degradation of phenol, sulfamethoxazole, and bisphenol A with a high mineralization efficiency. Its kinetic constants showed insignificant changes under various anions and a wide pH range of 1–9. More importantly, it was energy-efficient for treating actual coking wastewater with a low energy consumption of 19.0 kWh kg_COD^–1. The superior performance of the CuBN-HCMs was contributed from ¹O₂ and ^•OH and its high ¹O₂ selectivity.