Promotion of electrochemical oxygen evolution reaction by chemical coupling of cobalt to molybdenum carbide

Abstract Herein, we report a novel strategy to promote electrochemical oxygen evolution reaction (OER) on cobalt (Co) surface by coupling Co to molybdenum carbide (Mo 2 C). Chemically coupled Co and Mo 2 C nanoparticles were synthesized through a simple heat treatment of the mixture containing Co and Mo precursors and graphitic carbon nitride (g-C 3 N 4 ). Transmission electron microscopy (TEM) images obviously showed that Co and Mo 2 C nanoparticles were coupled at Co/Mo 2 C interfaces. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculation results revealed that electrons were transferred from Co to Mo 2 C nanoparticles across the interfaces. The electron transfer makes the Co surface more electrophilic by d -band center of Co upshift, leading to an increase in OH − affinity. As a result, the Co nanoparticles coupled with Mo 2 C have OER-favorable Co-oxo and Co-hydroxo configuration within their oxidized surfaces, and hence, can accelerate the overall OER than bare Co nanoparticles. This work demonstrates that the Co nanoparticles chemically coupled to Mo 2 C exhibited excellent OER activity and stability in an alkaline electrolyte and suggests a promising way to design an active OER catalyst.