Tannic acid-Fe coordination derived Fe/N-doped carbon hybrids for catalytic oxidation processes

Abstract

Novel nano-sized iron carbides and/or iron nitrogen clusters embedded into porous N-doped carbon (CP-Fe-N) samples were derived from a Fe-tannic acid coordination compound and used as highly reactive Fenton-like catalysts to oxidize recalcitrant organics via peroxymonosulfate (PMS) activation. The CP-Fe-N hybrids possessed superior catalytic activity, benefiting from uniformly distributed Fe₃C and Fe-Nₓ active sites into N-doped graphitic carbon in a hierarchically porous structure, which not only provided the channels for rapid mass transfer but also guaranteed the exposure of the highly catalytic active sites. The effects of several important factors, such as reaction temperature, initial pH and inorganic anions, on the removal of recalcitrant organics have been elucidated. Radical quenching and electron paramagnetic resonance experiments demonstrated that a large number of reactive oxygen species (ROS: ¹O₂ and O₂•⁻) were responsible for the contaminant degradation. The Fe-tannic acid coordination compound was a renewable source for the synthesis of magnetic CP-Fe-N hybrids, which favored magnetic separation for reuse. This work demonstrated the great potential of metal-tannic acid coordination as effective precursors to fabricate novel functional materials and their excellent application for environmental remediation.