CoO/Co/N-C nanoparticles embedded in carbon as mediate for oxygen reduction electrocatalysts

A series of CoO/Co/N-C catalysts are synthesized by the self-polymerization of dopamine in the presence of Co2+ followed by subsequent calcination. The optimized CoO/Co/N-C-10–700 catalyst possesses a large surface area (339.18 m2 g−1), a micro-mesoporous structure and abundant active sites. The nitrogen doped carbon layers can not only avoid the leakage of catalytic sites from the matrix, but also reduce the interparticle resistance for electronic and ionic transportation. Co-N-C, acting as the main active sites, contributes much to the good oxygen reduction reactivity (ORR). CoO/Co nanoparticles can enhance the conductivity of the material and are favorable for the reduction or disproportionation of peroxide species. The synergetic effect between them can efficiently boost the charge transfer ability and provide more active sites. The CoO/Co/N-C-10–700 catalyst displays a high onset potential (0.97 V vs. RHE), a large limiting current density (4.0 mA cm−2 at 0.04 V vs. RHE) and a good cycling stability. This investigation opens a new window to design low cost ORR catalyst with high catalytic activity.