Fe, Co, N-doped composite as an efficient catalyst for oxygen reduction and oxygen evolution reaction

A Fe, Co, N doping hierarchical carbon composite was prepared using stepwise pyrolysis. The prepared composite exhibited excellent oxygen reduction reaction (ORR) activity with a half-wave potential (E 1/2 ) of 0.88 V (vs. reversible hydrogen electrode, RHE), which was higher than the commercial 20 wt% Pt/C (E 1/2  = 0.83 V). The oxygen evolution reaction (OER) activity of the prepared catalysts with the potential at 10 mA cm −2 (E j10 ) of 1.543 V was lower than that of the commercial RuO 2 (E j10  = 1.586 V). The corresponding turnover frequency (TOF) of FeCo@NC-3N-900 was 0.076 O 2 s −1 at E 1/2 (TOF of Pt/C was 0.057 O 2 s −1 at E 1/2 ) in ORR and 0.056 O 2 s −1 at E j10 (TOF of RuO 2 was 0.001 O 2 s −1 at E j10 ) in OER. As a result, the performance of the Zn-air battery assembled with FeCo@NC-3N-900 was better than that of the commercial Pt/C + RuO 2 . At the same time, Co was found that can elevate the ORR activity of the prepared composites by improving the mass diffusion, and FeCo alloy elevate the OER activity by improving the electron transfer. This work provided an efficient method for the preparation of ORR/OER bifunctional catalyst.