Ultrafine CoFe Alloy Nanoparticles Confined in Highly Ordered Mesoporous Carbon Films as Catalysts for the Oxygen Evolution Reaction

Thin carbon films with two different kinds of mesoporous structures (three-dimensional (3D) cubic and two-dimensional (2D) hexagonal) loaded with CoFe alloy nanoparticles have been successfully synthesized by a dip-coating method with high-temperature calcination under a N 2 atmosphere. Ultrafine bimetallic CoFe nanoparticles are introduced into these two types of mesoporous carbon films as electrochemically active sites. Comparable experiments indicate that the 3D cubic mesoporous carbon film with embedded ultrafine CoFe nanoparticles exhibites a larger electrochemical surface area and lower charge transfer impedance compared with the 2D hexagonal mesoporous carbon film as a supporting material. This material shows a superior electrochemical catalytic performance for the oxygen evolution reaction (OER) with a lower overpotential (η 10 ) of 366 mV ( j = 10 mA cm –2 ), outperforming a 2D hexagonal mesoporous carbon film (386 mV) at the same current density.