Nitrogen-doped graphene-supported Co/CoNx nanohybrid as a highly efficient electrocatalyst for oxygen reduction reaction in an alkaline medium

Abstract

In this work, we utilize a one-step pyrolysis method to thermally synthesize a non-precious cobalt-based nitrogen-doped graphene (Co-NG) using graphene oxide (GO) and guanidine hydrochloride (GuHCl) with a small amount of CoCl₂ precursor as a low-cost and highly efficient catalyst for the oxygen reduction reaction (ORR). The synthesized cobalt-based nitrogen-doped graphene (Co-NG) was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of the Co-NG composite towards the ORR was evaluated using linear sweep voltammetry method. Electrochemical measurements reveal that the obtained Co-NG 850 composite has excellent catalytic activity towards the ORR in an alkaline electrolyte, including a large kinetic-limiting current density and good stability, as well as it exhibits the desirable four-electron pathway for the formation of water. These superior properties make the Co-NG 850 a promising cathode catalyst for alkaline fuel cells.