The role of trace Fe in Fe–N-doped amorphous carbon with excellent electrocatalytic performance for oxygen reduction reaction

•Fe–N-doped amorphous carbon film catalyst for oxygen reduction was synthesized.•The catalyst was obtained by dripping iron acetate into N-doped carbon and annealing.•The optimized catalyst showed excellent activity, stability and methanol tolerance.•The role of Fe was studied by tuning the Fe content and annealing temperature.•Trace Fe in film was supposed to form high active FeN4 sites with pyridinic N.

Synthesized by dripping iron acetate into the N-doped carbon film enriched with pyridinic N and followed by annealing at 800 °C, Fe–N-doped amorphous carbon (dFe–N-C) with an Fe content of 0.2 at.% showed excellent electrocatalytic activity, stability and methanol tolerance via a four-electron pathway for oxygen reduction reaction (ORR), which outperformed commercial Pt/C catalyst. More importantly, by tuning the Fe content and annealing temperature, the trace Fe in dFe–N-C was supposed to form high active FeN4 sites with pyridinic N and played an important role in the excellent electrocatalytic performance for ORR.