Constructing Atomic-level Dispersed Fe-N-C Catalyst to Enhance Photo-Fenton Activity for Water Purification.

Traditional Fenton technology encounters significant challenges in efficiently removing pharmaceuticals and personal care products (PPCPs) from water to meet established water purification standards. In this study, a Fe single-atom catalyst (FeSAC/CN-10) with Fe-N/C coordination was synthesized via thermal polymerization and photoreduction, anchoring Fe atoms onto a carbon nitride (g-C3N4) support. The Fe coordination configuration was verified using X-ray absorption fine structure (XAFS) spectroscopy, and the resulting catalyst was applied in the heterogeneous photo-Fenton degradation of PPCPs. Under visible light, FeSAC/CN-10 effectively degraded 97.8% of a typical PPCP, maintained high activity across a pH range of 2-6, demonstrated broad-spectrum degradation capability toward various PPCPs, and exhibited good reusability in cyclic experiments, highlighting its promising application potential. This coordination structure provided highly uniform atomic-level active sites and introduced Fe-derived impurity energy levels, as indicated by the DFT calculations, which may favor charge separation and electron transfer. The enhanced charge-carrier dynamics facilitated the Fe2+/Fe3+ redox cycle, accelerating H2O2 activation and the generation of reactive oxygen species (·OH, ·O2-, and 1O2), which ultimately resulted in superior photo-Fenton degradation performance. These findings support a plausible structure-property-performance relationship in which atomically dispersed Fe-N/C sites regulate the electronic structure of g-C3N4, enhance charge separation, and consequently improve heterogeneous photo-Fenton activity.