Energy-Efficient Electro-Fenton Oxidation Enabled by CoCu Dual-Atom Catalysts with High Oxygen Utilization

The Electro-Fenton (EF) technique offers a promising strategy for recalcitrant organic pollutant removal by coupling the two-electron oxygen reduction reaction (2e^- ORR) for H₂O₂ synthesis with its subsequent activation to •OH via one-electron (1e^-) reduction. To address the distinct favorable active sites and mismatched selectivity between 2e^- ORR and 1e^- H₂O₂ activation, we develop an integrated 2 + 1e^- tandem ORR catalyst with CoCu diatomic pairs (CoCu-DACs-CN) and cyano modification to improve oxygen capture and utilization efficiency (OUE, 39.8%). The CoCu-DACs-CN-based EF system achieves 100.0% of bisphenol A (BPA) in 40.0 min with a high-rate constant of k = 0.57 min^-1. Theoretical calculations indicate that the -CN moieties in CoCu-DACs-CN greatly facilitate O₂ adsorption, which further migrates to the Co site to proceed 2e^- ORR with a reduced energy barrier. The generated H₂O₂ spontaneously migrates to the surrounding Cu site for in situ activation to generate •OH. Long-term operation of a CoCu-DACs-CN-equipped flow-cell device that maintains 100.0% bisphenol A removal even without O₂/air pumping. Technoeconomic analysis indicates that the CoCu-DACs-CN-based EF process effectively reduced electrical energy consumption by 74.4%, demonstrating its promise for energy-efficient wastewater treatment.