Enhanced redox cycle of Fe³⁺/Fe²⁺ on Fe@NC by boron: Fast electron transfer and long-term stability for Fenton-like reaction

In this work, Fe@NC/B material is successfully synthesized and in-situ supported on the surface of amorphous boron (B) using a simple pyrolysis method. The interface between Fe species and B is improved by introducing N-doped carbon (NC) layers as intermediate, fast electron transfer from B to Fe@NC can therefore be achieved, thus could promote the fast redox cycle of Fe³⁺/Fe²⁺. The obtained material can therefore activate peroxymonosulfate (PMS) effectively to degrade Bisphenol A (BPA), a fast degradation rate and a very long lifetime in a continous tubular reactor are realized. Moreover, experiments and DFT calculation indicate that Fe²⁺ containing species are the dominated active sites, while the exposed B atoms and structure defect of B can also activate PMS directly to produce SO₄^•− and ¹O₂ species for BPA degradation. In addition, boric acid is the oxidation product of B, which can be dissolved into the aqueous solution and expose fresh B species again for PMS activation. The combination of B with Fe@NC provide novel materials for long term PMS activation, thus could promote the real application of persulfates on an industrial scale.