Active catalysts based on cobalt oxide@cobalt/N-C nanocomposites for oxygen reduction reaction in alkaline solutions

Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a highly promising CoO@Co/N-C (where N-C represents a N-doped carbon material) catalyst, achieving an onset potential of 0.99 V (versus the reversible hydrogen electrode (RHE)) and a limiting current density of 7.07 mA center dot cm(-2) (at 0.3 V versus RHE) at a rotation rate of 2,500 rpm in an O-2-saturated 0.1 M KOH solution, comparable to a commercial Pt/C catalyst. The H-2-O-2 alkaline fuel cell test of CoO@Co/N-C as the cathode reveals a maximum power density of 237 mW center dot cm(-2). Detailed investigation clarifies that a synergistic effect, induced by C-N, Co-N-C, and CoO/Co moieties, is responsible for the bulk of the gain in catalytic activity.