Axially coordinated cobalt single-atom membrane enabling electron-transfer-singlet oxygen synergy for highly selective micropollutant oxidation.

The presence of natural organic matter and inorganic anions often impedes the effectiveness of advanced oxidation processes in removing micropollutants from aquatic environments. Considering that most micropollutants contain electron-rich functional groups, selective degradation through non-radical pathways offers a promising strategy to eliminate target contaminants. In this study, a carbon-based cobalt single-atom catalytic membrane was fabricated via a low-temperature, controlled synthesis to suppress carbon substrate pyrolysis and avoid the formation of diverse catalytic active sites, facilitating a completely non-radical activation route with Co active sites. The synergistic action of singlet oxygen and the electron transfer process enables efficient pollutant degradation while reducing oligomer accumulation. In addition, short-range electron transfer enhances oxidant utilization efficiency. Density functional theory calculations reveal that peroxymonosulfate activation predominantly proceeds through an electron-transfer pathway. Moreover, axial coordination engineering increases the overlap between O 2p and Co 3d orbitals, thereby accelerating interfacial free electron transfer. Coupled with membrane pore confinement-enhanced mass transport, the selective single-atom catalytic system enables the targeted generation and in situ utilization of reactive oxygen species, addressing a long-standing challenge in heterogeneous Fenton-like reactions. As a result, the catalytic membrane exhibits exceptional reactive oxygen species utilization efficiency and highly selective pollutant removal. The membrane achieved over 98% removal of electron-rich contaminants during 4000 min of continuous operation under ultralow driving pressure. Even in complex water matrices, the removal efficiency remained above 95%, demonstrating remarkable robustness and practical applicability.