【J. Phys. Chem. C】 2015, 119 (5), 2583-2588.
Zhao, Y.; Kamiya, K.; Hashimoto, K.; Nakanishi, S.
Efficient electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical components of various energy conversion devices such as regenerative fuel cells and metal–air batteries. Herein, we report bifunctional transition-metal-doped carbon/nitrogen (M/C/N) materials that simultaneously electrocatalyze the ORR and OER. The OER potential of the Fe/C/N catalyst at a current density of 10 mA cm–2 was 1.59 VRHE, and its ORR half-wave potential was 0.83 VRHE. Significantly, the Fe/C/N catalyst provided a potential gap of 0.76 V between the OER potential (at 10 mA cm–2) and the ORR half-wave potential; this is the highest activity reported to date for a non-precious-metal catalyst. Two types of active center, the transition metal and a nitrogen atom, are likely responsible for the oxygen bifunctional activity.