Medium-Entropy NiFeMnCu Catalysts Enhance Aeration-Free Electrochemical Advanced Oxidation

Advanced oxidation processes are among the mainstream and high-efficiency technologies for treating pharmaceutically active compounds and other water pollutants. However, most current electro-Fenton (EF) processes still rely on the use of Fe²⁺ and oxidizing agents, and the secondary pollution problem caused by metal ion leaching resulting therefrom has not yet been effectively addressed. Herein, we report a dual-system four-electrode EF cell that requires no addition of chemical reagents. The system employs a 300-nm-thick NiFeMnCu (NFMC) thin film, which not only functions as an OER collector for oxygen generation from both Anode I and Anode II, but also serves as a working electrode with a two-electron pathway to produce H₂O₂ through the electrochemical reduction of O₂ at Cathode I. Furthermore, by integrating the Cathode II, NFMC cathode for the second-step sequential electrocatalytic reaction, the generation of H₂O₂ and its conversion to ·OH can be achieved. This catalytic system can effectively avoid problems such as metal sludge accumulation. When cefadroxil is used as the target pollutant, its removal can be completed within 30 min. Owing to the adoption of low-cost, durable, and scalable electrode materials, this process possesses high feasibility for practical application.