Fabrication of Fe-NC single-atom catalysts via supercritical CO2 deposition for enhanced peroxymonosulfate activation

Currently reported Fe-NC catalysts for peroxymonosulfate (PMS) activation are mostly pyrolytically derived nanoparticle systems, which often suffer from low atomic utilization efficiency of the metal species. In this study, a single-atom Fe-NC catalyst was fabricated using a supercritical CO₂ deposition method, with iron(III) acetylacetonate as the metal precursor and a nitrogen-doped carbon material as the support. The as-prepared catalyst was employed to activate PMS for the degradation of Rhodamine B (RhB). Characterization by STEM, XRD, and BET analyses confirmed that the nitrogen-doped carbon support exhibits a high specific surface area and substantial nitrogen content. Aberration-corrected electron microscopy directly evidenced the uniform dispersion of isolated Fe atoms on the support surface. After 5   min of reaction, an RhB removal efficiency of 82.3% was achieved, corresponding to a turnover frequency of 2.73   min⁻¹. These results highlight the effectiveness of atomically dispersed Fe sites in activating PMS to generate reactive oxygen species.