Electronic Modulation of Internal-Driven Fenton-like Pathways in Single-Atom Enzyme Catalysis: Regulating Pathway...

Although peroxymonosulfate (PMS)-based oxidation processes are widely used in water treatment, their reliance on continuous external oxidant input results in elevated operational costs and associated environmental impacts. In PMS systems, the degradation of emerging contaminants (ECs) can proceed not only through oxidant-driven reactions but also via an internal-driven pathway, in which ECs act as intrinsic electron donors and directly participate in Fe-site-mediated transformations. However, the role of this pathway in PMS-activated systems and its variability among different ECs remain unclear. Herein, a single-atom enzyme system with Fe-N₃ and Fe-N-C anchoring onto the nitrogen-doped carbon (FeN₃/NC-SAE) was fabricated to elucidate the role of internal-driven pathways in PMS-activated systems based on versatile ECs. By selecting ECs with distinct electronic properties, systematic differences in degradation pathways were observed. Electron-donating ECs exhibited higher reaction potential (ΔE₁) responses and enhanced reactivity in the PMS-free and PMS-containing systems, whereas electron-accepting ECs showed reduced activity. These results indicated that ECs-derived electrons participated in the internal-driven pathway alongside PMS activation. Continuous-flow experiments also demonstrated stable ECs removal with reduced PMS consumption. This work provides insight into how the electronic properties of ECs regulate the internal-driven pathway in PMS-based catalytic systems.