The strong metal–support interactions induced electrocatalytic three-electron oxygen reduction to hydroxyl radicals for water treatment

As a promising environmental remediation technology, the electro-Fenton (EF) process is mainly limited by the two rate-limiting steps, which are H 2 O 2 generation and activation. The electrocatalytic three-electron oxygen reduction reaction (3e − ORR) can directly activate oxygen to hydroxyl radicals (•OH), which is expected to break through the rate-limiting steps of the EF process. However, limited success has been achieved in the design of 3e − ORR electrocatalysts. Herein, we propose Cu/CoSe 2 /C with the strong metal–support interactions to enhance the 3e − ORR process, exhibiting remarkable reactivity and stability for •OH generation. Both experiment and DFT calculation results reveal that CoSe 2 is conducive to the generation of H 2 O 2 . Meanwhile, the metallic Cu can enhance the adsorption strength of *H 2 O 2 intermediates and thus promotes the one-electron reduction to •OH. The Cu/CoSe 2 /C catalyst exhibits the electron-transfer number close to 3.0 during the ORR process, and exhibits the outstanding •OH generation performance, achieving a higher apparent rate constant (6.0 times faster) toward ciprofloxacin compared with its analogy without the SMSI effect. Our work represents that the SMSI effect endows Cu/CoSe 2 /C high activity and selectivity for •OH generation, providing a unique perspective for the design of a high-efficiency 3e − ORR catalyst.