Dual carbon-hosted Co-N3 enabling unusual reaction pathway for efficient oxygen reduction reaction

Single-atom cobalt-nitrogen-carbon (Co-N-C) has emerged as one of the most promising electrocatalysts for the oxygen reduction reaction (ORR) as it has the utmost atomic utilization efficiency and may avoid possible Fenton reactions. Herein, we report dual carbon-supported single-atom cobalt with the unusual Co-N coordination number of three (Co-N3-C) as an efficient catalyst for the ORR. The combination of experiments and density functional theory calculations reveal that the Co-N3-C would experience an activation process and be favorable to lowering the energy barriers of the intermediates, leading to accelerated reaction kinetics. The as-prepared Co-N3-C catalyst exhibited unprecedented ORR activity with a half-wave potential of 0.891 V versus reversible hydrogen electrode and outstanding stability under alkaline conditions, not only outperforming the previously reported Co-based catalysts but also surpassing state-of-the-art Pt/C catalyst. The current work may provide a new insight into the engineering of the single-atom coordination environment to improve the catalytic activity.