Bimetallic Iron–Cobalt Nanoparticles Coated\nwith Amorphous Carbon for Oxygen Evolution

Abstract

Because\nof the adjustable electronic structure of bimetallic alloys,\nthey have received much attention in electrocatalytic reactions. However,\nto date, there is a lack of effective methods to synthesize bimetallic\nnanoalloys with controllable metal proportions in the active species\nof the catalysts prepared by a high-temperature annealing method,\nleading to inferior catalytic activity and difficulty in identifying\nthe active sites. Here, we synthesize iron (Fe)–cobalt (Co)-based\nnanoparticles coated with a few layers of amorphous carbon shell (<1\nnm) and with Co₇Fe₃ alloy as the core by facile\npyrolysis of a bimetallic Fe–Co-based tartrate, which exhibits\nexcellent oxygen evolution reaction (OER) activity with a low overpotential\nof 272 mV at a current density of 10 mA cm^–2 and\ngood durability in alkaline media. Compared with single-metal Fe/Co\ntartrate-derived catalysts, a bimetallic Fe–Co tartrate-derived\ncatalyst with Co₇Fe₃O_<i>x</i> active sites shows higher charge-transfer ability and a lower\nOER barrier (approximately 285 kJ mol^–1). For the\nfirst time, this work demonstrates that Fe–Co-based tartrate\ncomplexes can be used as precursors to construct high-performance\nbimetallic Fe–Co-based nanocomposite catalysts with controllable\nactive sites for electrocatalytic OER.