Bimetallic Iron–Cobalt Nanoparticles Coated with Amorphous Carbon for Oxygen Evolution

Because of the adjustable electronic structure of bimetallic alloys, they have received much attention in electrocatalytic reactions. However, to date, there is a lack of effective methods to synthesize bimetallic nanoalloys with controllable metal proportions in the active species of the catalysts prepared by a high-temperature annealing method, leading to inferior catalytic activity and difficulty in identifying the active sites. Here, we synthesize iron (Fe)–cobalt (Co)-based nanoparticles coated with a few layers of amorphous carbon shell (<1 nm) and with Co7Fe3 alloy as the core by facile pyrolysis of a bimetallic Fe–Co-based tartrate, which exhibits excellent oxygen evolution reaction (OER) activity with a low overpotential of 272 mV at a current density of 10 mA cm–2 and good durability in alkaline media. Compared with single-metal Fe/Co tartrate-derived catalysts, a bimetallic Fe–Co tartrate-derived catalyst with Co7Fe3Ox active sites shows higher charge-transfer ability and a lower OER barrier (approximately 285 kJ mol–1). For the first time, this work demonstrates that Fe–Co-based tartrate complexes can be used as precursors to construct high-performance bimetallic Fe–Co-based nanocomposite catalysts with controllable active sites for electrocatalytic OER.