Nitrogen-doped ordered mesoporous carbon: synthesis and active sites for electrocatalysis of oxygen reduction reaction

• A novel method is developed to synthesize ordered mesoporous carbon.
• The carbon catalyst outperforms the Pt counterpart for the oxygen reduction reaction.
• The catalytic active sites for the ORR are nitrogen-activated carbon atoms.

In the present work, a novel impregnation method, namely vaporization-capillary condensation method, is developed to synthesize nitrogen-doped ordered mesoporous carbon. This method allows for the preferential infiltration of the carbon precursor (like pyrrole) into the mesochannels other than into the texture pores or onto the outer wall, which outperforms the traditional methods like ‘incipient wetness impregnation’. It is found that the synthesized carbon shows high specific surface area and activity towards the oxygen reduction reaction (ORR). Methanol fuel cell test thereafter reveals two times higher performance with such catalyst than Pt. Moreover, the electrocatalytic activity is correlated with the fraction of nitrogen-activated carbon atoms, indicating that in such catalysts the active sites are C–N groups. The obtained electrochemical results and surface analysis suggest that the transition metal might not be directly involved in the active sites.

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