Graphene Supported Co-g‑C₃N₄ as a Novel Metal–Macrocyclic Electrocatalyst for the Oxygen Reduction Reaction in Fuel Cells

Graphitic carbon nitride (g-C₃N₄) polymer was doped with cobalt species and supported on a similar sp² structure graphene, to form a novel nitrogen–metal macrocyclic catalyst for the oxygen reduction reaction (ORR) in alkaline fuel cells. The structural characterizations confirmed the formation of Co–N bonds and the close electron coupling between Co-g-C₃N₄ and graphene sheets. The electrocatalytic measurements demonstrated Co-g-C₃N₄-catalyzed reduction of oxygen mainly in a four electron pathway. The improvement of ORR activity is closely related to the abundant accessible Co–N_<i>x</i> active sites and fast charge transfer at the interfaces of Co-g-C₃N₄/graphene. Also, Co-g-C₃N₄@graphene exhibited comparable ORR activity, better durability, and methanol tolerance ability in comparison to Pt/C, and bodes well for a promising non-noble cathode catalyst for the application of direct methanol fuel cells. The chemical doping strategy in this work would be helpful to improve other present catalysts for fuel cell applications