Switching Peroxymonosulfate Redox Routes by Manipulating Spinel Tetrahedral and Octahedral Site Activity for Multi‐Scenario Wastewater Treatment

Vollständiger Abstract

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ABSTRACT For diverse wastewater treatment scenarios, achieving controllable switching of reactive oxygen species within a unified catalytic system remains a major challenge. Here, an inert cation substitution strategy is proposed to regulate tetrahedral and octahedral Co activity in Co 3 O 4 , enabling controllable switching between radical and nonradical pathways. Octahedral‐Co‐enriched ZnCo 2 O 4 (ZCO) selectively directs peroxymonosulfate (PMS) activation toward the 1 O 2 pathway (95.8% contribution), whereas tetrahedral‐Co‐dominated CoAl 2 O 4 (CAO) favors radical oxidation, with •OH (76.4%) and SO 4 •− (21.7%) dominating. This polyhedral‐dependent pathway control leads to distinct oxidation behaviors. Notably, the ZCO/PMS system achieved nearly 100% o‐nitrophenol (ONP) degradation within 4 min, with a k ‐value of 71.81 min −1 M −1 , 32.2 times that of Co 3 O 4 . Multiple lines of evidence reveal that polyhedral‐site engineering governs PMS adsorption geometry, interfacial charge redistribution, and O─O bond activation, thereby determining pathway selection. These differentiated functions were further translated into bench‐scale municipal wastewater treatment, with ZCO/PMS increasing the effluent Biochemical oxygen demand/chemical oxygen demand (BOD/COD) ratio from below 0.3 to consistently above 0.5 over 80 h and CAO/PMS decreasing the effluent TOC from ∼25 mg L −1 to below 12 mg L −1 over 60 h. Both systems exhibited low biotoxicity and favorable sustainability, offering a practical route toward selective energy‐efficient advanced oxidation.