3D N-doped ordered mesoporous carbon supported single-atom Fe-N-C catalysts with superior performance for oxygen reduction reaction and zinc-air battery

[Display omitted] •Graphitic N dopants embedded in carbon matrix boost the intrinsic activity of single-atom FeN4 sites.•3D interconnected pores of ordered mesoporous carbon framework endow dense Fe-N-C sites accessible.•Fe-N-C/N-OMC provides a half-wave potential of 0.93 V, a kinetic current density of 57.4 mA cm-2, a turnover frequency (TOF) of 38.4 s-1 and a mass activity of 66.4 A mgFe-1 towards ORR in 0.1 M KOH.•Fe-N-C/N-OMC shows a half-wave potential of 0.73 V towards ORR in 0.5 M H2SO4, comparable to Pt/C. Single-atom Fe-N-C electrocatalysts have emerged as the most promising oxygen reduction reaction (ORR) catalyst. However, the low Fe loading and inaccessibility of Fe-N-C sites limit the overall ORR activity. Here, we report an efficient single-atom electrocatalyst (Fe-N-C/N-OMC) with Fe-N-C sites embedded in three-dimensional (3D) N-doped ordered mesoporous carbon framework. Fe-N-C/N-OMC shows high half-wave potential, kinetic current density, turnover frequency and mass activity towards ORR in alkaline electrolyte. Experiments and theoretical calculations suggest that the ultra-high ORR activity stems from the boosted intrinsic activity of FeN4 sites by graphitic N dopants, high density of accessible active site generated by high Fe and N loadings and ordered mesoporous carbon structure as well as facilitated mass and electron transport in 3D interconnected pores. Fe-N-C/N-OMC also shows comparable ORR activity to Pt/C in acidic electrolyte. As the cathode for zinc-air battery, Fe-N-C/N-OMC exhibits high open-circuit voltage, high power density and remarkable durability.