Synergistic dual-catalytic sites in quenching-engineered Fe-N-Cu for peroxymonosulfate activation: A mechanistic revelation

Catalytic site regulation is pivotal to advancing heterogeneous catalytic oxidation technology. This study employs a quenching process to construct N-bridged asymmetric Cu-N-Fe dual catalytic sites on the CuO surface, activating peroxymonosulfate (PMS) to achieve highly efficient removal of aquatic pollutants. This provides a regulatory strategy for heterogeneous catalytic oxidation technology. Fe atom doping on the CuO surface forms an asymmetric Fe-N-Cu bond bridge structure, altering the interfacial electronic structure and shifting the d-band centre upward (from −2.215 eV to −2.184 eV). This significantly enhances PMS adsorption capacity and substantially increases charge transfer capability (from 0.315 e to 0.705 e), thereby enabling a dual-path activation mechanism. Specifically, PMS first adsorbs onto adjacent Fe-Cu active sites, generating •SO₄⁻ and •OH radicals. The surface reaction complex formed at the Fe site transfers electrons from the pollutant to Cu via the Fe-N-Cu bond bridge, enabling highly efficient pollutant degradation. This system exhibits outstanding stability and adaptability, with a 5.25-fold higher degradation kinetic constant and 1.32-fold greater oxidant utilization efficiency compared to CuO. This study not only successfully constructed dual catalytic sites but also elucidated their novel structure-function synergistic catalytic mechanism.