Engineering crystalline CoOOH anchored on an N-doped carbon support as a durable electrocatalyst for the oxygen reduction reaction

Finding highly active, low-cost and stable electro-catalysts for the oxygen reduction reaction is challenging but crucial for several applications such as fuel cells and metal batteries. Herein, we report a novel electro-catalyst of crystalline CoOOH anchored on an N-doped carbon support through a facile method, and we explore its origin of activity via investigating the correlation between the composition of the catalyst and its electrochemical properties. Nitrogen is successfully incorporated into a carbon support, and CoOOH is desirably anchored on a carbon matrix forming Co-N coordination sites in the catalyst, which is revealed to be responsible for the much enhanced oxygen reduction activity compared to the oxygen reduction activities of the electrocatalysts having either single-doped nitrogen or anchored CoOOH species in a carbon support. Furthermore, it is deduced that the active sites for enhanced oxygen reduction can be attributed to Co-N_x, carbon atoms neighboring the doped nitrogen and even the CoOOH species. The optimized catalyst CoOOH@NC-175/300 shows lower onset potential and half-wave potential and much better cyclic stability compared to those of the state-of-the-art Pt/C catalysts. This novel finding provides a new approach for the rational engineering of low-cost, highly active and stable non-precious ORR electrocatalysts for applications in energy conversion and storage.