Facile synthesis of Co-N₄-doped mesoporous carbon for oxygen reduction reaction

The oxygen reduction reaction (ORR) is a critical factor in fuel cells that has attracted significant research attention. Non-precious metal catalysts have improved the ORR activity considerably, but they still exhibit poorer ORR performance than commercial Pt-based catalysts. In this study, Co-N-4-doped mesoporous carbon (Co-N-4-MC) was prepared for the ORR using cobalt-azides as the Co-N-4-containing precursor, and ordered mesoporous silica SBA-15 as a template for achieving mesoporous structures. The Co-N-4-MC electrode exhibited remarkable ORR activity in an alkaline medium (a half-wave potential of -0.15 V vs. MMO, only similar to 19 mV deviation from the commercial Pt/C catalyst), high selectivity (electron-transfer number similar to 4) and excellent electrochemical stability (similar to 8 mV negative shift of the half-wave potential after 1000 cycles). The good performance of the Co-N-4- MC electrode was attributed to the synergetic effects of N-4, C and Co. In particular, the existence of graphitic pores in the Co-N-4-MC catalyst facilitated the diffusion of O-2 to the catalytic active sites, which benefited the progression of the ORR on the Co-N-4-MC catalyst. (C) 2017 The Electrochemical Society.