Simultaneously Improving the Stability and Singlet Oxygen Formation via Interlayer Confinement Effects for Efficient and Sustainable Water Purification

ABSTRACT Single‐atom catalysts (SACs) are highly promising for Fenton‐like catalytic degradation of refractory organic contaminants in waters. Nevertheless, surface‐exposed single‐atom sites on carbon supports are prone to premature deactivation and limit the utilization of short‐lived reactive oxygen species in peroxymonosulfate (PMS) activation processes, resulting in an inherent trade‐off between catalytic activity and stability. Herein, we report an interlayer confinement strategy to precisely anchor Fe‐N 4 monatomic sites within the interlayers of two‐dimensional graphitic carbon nitride (SA‐Fe inter ‐CN). Benefiting from the interlayer confinement effect, SA‐Fe inter ‐CN exhibited significantly enhanced PMS activation performance compared with the surface‐supported counterpart (SA‐Fe sur ‐CN), achieving a high apparent reaction rate constant of 3.317 min −1 and maintaining 100% degradation efficiency after eight consecutive cycles, demonstrating excellent stability. Theoretical simulations revealed that the interlayer confinement effect strengthens metal‐support interactions and lowers the energy barrier for singlet oxygen ( 1 O 2 ) formation, thereby promoting 1 O 2 generation and utilization. The SA‐Fe inter ‐CN/PMS system also showed strong resistance to interference in complex water matrices and real wastewater. Life cycle assessment and long‐term continuous‐flow operation further confirmed its practical applicability. This work resolves the long‐standing activity‐stability trade‐off of SACs in advanced oxidation processes via the interlayer confinement effect, offering a robust strategy for efficient and sustainable wastewater treatment.