Dual-Template Construction of Iron–Nitrogen-Codoped Hierarchically Porous Carbon Electrocatalyst for Oxygen Reduction Reaction

Abstract

The oxygen reduction reaction (ORR) is identified as a core issue in the technologies for convert energy, especially in proton-exchange membrane fuel cell (PEMFC). Highly reactive, low-cost, and durable electrocatalysts are ideal for the sluggish ORR. Herein, iron–nitrogen codoped hierarchically porous carbon (Fe-N-HPC-0.05) electrocatalytic material was prepared by a dual-template-assisted strategy. Upon accurate control of metal–organic framework (MOF) composition, Fe/Fe3C nanocrystals, FeNx, and N-doped carbon were produced. Fe-N-HPC-0.05 shows enhanced ORR performance in both alkaline and acidic conditions by taking advantage of the hierarchically porous structure and numerous active sites. In alkaline conditions, Fe-N-HPC-0.05 exhibited similar onset and half-wave potentials compared with 1.02 and 0.85 V for commercial Pt/C, respectively. In acidic conditions, Fe-N-HPC-0.05 possessed half-wave potential of 0.78 V, only 60 mV lower than that of Pt/C (0.84 V), indicating that the Fe-N-HPC-0.05 catalyst has application prospects in PEMFCs. This work also provides the design principle for increasing the ORR catalytic activity of hierarchically porous structure with exposed active sites.