Facile Synthesis of Co-N4-Doped Mesoporous Carbon for Oxygen Reduction Reaction

Abstract

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-N4-doped mesoporous carbon (Co-N4-MC) was prepared for the ORR using cobalt-azides as the Co-N4-containing precursor, and ordered mesoporous silica SBA-15 as a template for achieving mesoporous structures. The Co-N4-MC electrode exhibited remarkable ORR activity in an alkaline medium (a half-wave potential of −0.15 V vs. MMO, only ∼19 mV deviation from the commercial Pt/C catalyst), high selectivity (electron-transfer number ∼4) and excellent electrochemical stability (∼8 mV negative shift of the half-wave potential after 1000 cycles). The good performance of the Co-N4-MC electrode was attributed to the synergetic effects of N4, C and Co. In particular, the existence of graphitic pores in the Co-N4-MC catalyst facilitated the diffusion of O2 to the catalytic active sites, which benefited the progression of the ORR on the Co-N4-MC catalyst.