Ferric carbide nanocrystals encapsulated in nitrogen-doped carbon nanotubes as an outstanding environmental catalyst

Nitrogen-doped carbon nanotubes encapsulating iron carbide (Fe₃C) nanocrystals (Fe₃C@NCNT) were fabricated by a simple and direct pyrolysis method using melamine and ferric chloride as the C, N and Fe precursors. The surface morphology, structure and composition of the Fe₃C@NCNT materials were thoroughly investigated. The nanomaterials were employed as novel catalysts for peroxymonosulfate (PMS) activation; outstanding efficiency, high stability and excellent reusability were observed in the catalytic oxidation of organics. The encapsulated Fe₃C nanoparticles played a key role in the emerging synergetic effects of the carbide and the protective graphitic layers. In addition, the quaternary N and trace amounts of iron on the CNT surface acted as the active sites. Various quenching experiments were carried out to elucidate the catalytic mechanism of Fe₃C@NCNT. It was found that singlet oxygen, superoxide, sulfate and hydroxyl radicals worked together to degrade phenol solutions. Due to their simple synthesis method, low-cost precursors, unique structure and excellent catalytic activity and stability, these novel iron-carbide-based composites have great potential as new strategic materials for environmental catalysis.