Fe containing template derived atomic Fe–N–C to boost Fenton-like reaction and charge migration analysis on highly active Fe–N4 sites

Persulfate-based advanced oxidation processes are promising technologies to solve water pollution. In this work, single iron atoms are anchored on three-dimensional N-doped carbon nanosheets by a chemical vapor deposition (CVD) method with ferrocene-loaded CaO as the hard template. The high surface density of Fe–N4 sites and abundant interconnected meso–macro pores are highly favorable for activating peroxymonosulfate (PMS) to produce superoxide radicals (O2˙−), giving rise to ultrahigh activity and excellent stability for pollutant degradation. Experiment and density functional theory (DFT) calculations reveal that Fe–N4 is the main active site, on which electrons transfer from C to Fe via the C–N–Fe bond to secure the low-valence state of Fe species for the redox process. This work proposes a new strategy for developing highly active single-atom materials by CVD and reveals mechanisms of PMS activation on single-atom activators.