Cascaded Fe-*OOH and Co-*H <sub>2</sub> O <sub>2</sub> Intermediates on Fe–Co Dual Sites for Orchestrated O <sub>2</sub> 3-Electron Electro-Fenton Pathways
Haoyang Zhang, Songwei Wang, Wei-Kang Wang, Jia-Rui Xi, Zhiming Wang, Ying Shi, Jia-Wen Bai, Wen‐Wei Li, Juan Xu, Guohua Zhao, Juan Xu, Guohua Zhao
Abstract
High Resolution Image Download MS PowerPoint Slide The heterogeneous electro-Fenton (HEF) process has emerged as a promising advanced oxidation technology for wastewater remediation, yet an insufficient mechanistic understanding of the interfacial electron transfer processes and intermediate evolution still limits further improvement of efficient in situ hydroxyl radical ( • OH) generation. Herein, we design Fe–Co bimetallic oxide catalysts for the HEF reaction via a novel 3-electron pathway and identify that the synergistic Fe–Co dual sites promoted the formation of critical intermediates: Fe-*OOH during the O 2 reduction and Co-*H 2 O 2 during H 2 O 2 activation. In situ Raman spectroscopy that directly captured these intermediates on catalyst surfaces, together with density functional theory (DFT) calculations, confirms that the Fe and Co sites facilitate the direct interfacial conversion of adsorbed H 2 O 2 to • OH via optimizing reaction kinetics that Fe predominantly drives the 2-electron O 2 to H 2 O 2 step, while Co efficiently activates 1-electron H 2 O 2 to • OH. In a continuous-flow reactor, the Fe–Co catalyst achieved ∼80% total organic carbon (TOC) and chemical oxygen demand (COD) removal over 15 h, with an energy efficiency of 0.04 kW·h·g –1 . This work provides fundamental insights into dual sites in boosting the HEF reaction at the molecular level, establishing a design principle of cathodic catalysts for environmental remediation.