Iron-nitrogen doped carbon with exclusive presence of FexN active sites as an efficient ORR electrocatalyst for Zn-air battery

In this work, we have found that a new Fe-N module, FexN (x = 2, 3, or 4), in which the N atoms insert the lattice of Fe matrix, also has high catalytic activity towards ORR. We synthesized the FexN module embedded N-doped carbon material (FexN/NC) via a facile metal-organic framework (MOF)-templated approach. The as-synthesized FexN/NC shows a superb catalytic ORR activity as well as high methanol tolerance. The highly efficient catalytic active sites (FexN module and well-doped N species) were mainly responsible for the superb ORR activity. The synergistic mechanisms of the N-doped carbon support and FexN moieties for ORR at molecular level were elucidated by density functional theory calculations. The excellent catalytic ORR performance make the FexN/NC catalyst be a promising candidate to replace the expensive Pt based cathodic catalyst in Zn-air batteries.