Nanoconfined Nitrogen-Doped Carbon-Coated Hierarchical TiCoN Composites with Enhanced ORR Performance

The high cost of platinum-based cathode catalysts for the oxygen reduction reaction (ORR) has long hampered the practical application of fuel cells. In-depth studies have shown titanium nitride (TiN) is an interesting non-precious-metal electrocatalysts for replacing Pt, due to their low cost, excellent catalytic properties, and stability. In this study, we report on a three-dimensional (3D) nitrogen-doped carbon-coated hierarchical Ti0.95Co0.05N composite, created using a one-step impregnation method followed by nitriding. The catalyst exhibited significantly enhanced ORR activity and excellent electrochemical stability. Our optimal catalyst, 20%C-Ti0.95Co0.05N, had an ORR performance almost comparable to 20% Pt/C in an alkaline medium, and a four-electron pathway was dominant during the ORR reaction. The significantly enhanced ORR performance of this catalyst is attributable to the following factors: the synergic effect of a carbon coating on the nitride nanoparticles (NPs), including the higher surface area and more exposed active-sites caused by the well-defined 3D structure resulting from the carbon coating; better mass transfer and electron transfer due to the carbon coating; the contribution of the doped carbon; and enhancement of the nitride's activity by doping with transition metal.