Bimetal- and nitrogen-codoped spherical porous carbon with efficient catalytic performance towards oxygen reduction reaction in alkaline media
Nonprecious-metal electrocatalysts have been intensively investigated, but how to keep a balance between their sustainability and competitive performance for the oxygen reduction reaction (ORR) is still a big challenge for energy applications. In this work, a type of bimetal- and nitrogen-codoped mesoporous carbon electrocatalyst (FeCo-N/C-800) was successfully synthesized via a simple hydrothermal method , followed by a calcination process at 800 °C in nitrogen atmosphere and an acid-etching process. The obtained FeCo-N/C-800 can act as a high-performance ORR catalyst with high onset and half-wave potentials (0.94 and 0.85 V), a large limiting current density (5.94 mA cm −2 ) and a four-electron reaction process in 0.1 M KOH solution, which can be comparable with commercial Pt/C catalyst. Additionally, the FeCo-N/C-800 exhibited superior long-term durability and high methanol tolerance. The excellent electrocatalytic performance of the FeCo-N/C-800 can be ascribed to the mesoporous structure (bimodal pores system), the synergetic interaction of the multiple ORR active sites, suitable N-doping level and the highly conductive carbon matrix. These structural features can promote efficiently the mass and electron transfer , provide abundant active sites for the adsorption and reaction of oxygen molecules, and thus improve the reaction kinetics. The present study not only provides a strategy for the synthesis of carbon-based electrocatalyst with high ORR catalytic activity and stability, but also demonstrates that the bimetal- and nitrogen-codoped carbon materials could be a class of competitive candidate for non-noble metal-based electrocatalysts.
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