A Nanoconfined FeCo₂O₄-Embedded Ceramic Membrane Regulates Electron Transfer in Peroxymonosulfate Activation to Selectively Generate Singlet Oxygen for Water Decontamination

Abstract

Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs), as a promising technology for water decontamination, are constrained by low reaction kinetics due to limited reaction selectivity and mass transfer. Herein, we designed a nanoconfined FeCo₂O₄-embedded ceramic membrane (FeCo₂O₄-CM) under flow-through pattern for PMS activation. Confining PMS and FeCo₂O₄ within nanochannels (3.0-4.7 nm) enhanced adsorption interactions (-7.84 eV vs -2.20 eV), thus boosting mass transfer. Nanoconfinement effect regulated electron transfer pathways from PMS to FeCo₂O₄-CM by modulating the active site transformation to ≡Co(III) in nanoconfined FeCo₂O₄-CM, enabling selectively generating ¹O₂. The primary role of ¹O₂ in the nanoconfined system was confirmed by kinetic solvent isotope experiments and indicative anthracene endoperoxide (DPAO₂). The system enabled 100% removal of atrazine (ATZ) within a hydraulic retention time of 2.124 ms, demonstrating a rate constant over 5 orders of magnitude higher than the nonconfined system (3.50 × 10³ s^-1 vs 0.42 min^-1). It also exhibited strong resilience to pH variations (3.3-9.0) and coexisting substances, demonstrating excellent stability indicated by consistent 100% ATZ removal for 14 days. This study sheds light on regulating electron transfer pathways to selectively generate ¹O₂ through the nanoconfinement effect, boosting the practical application of PMS-based AOPs in environmental remediation and potentially applying them to various other AOPs.