FeNₓ and γ-Fe₂O₃ co-functionalized hollow graphitic carbon nanofibers for efficient oxygen reduction in an alkaline medium
2020
Yu, Qiang | Lian, Sitian | Li, Jiantao | Yu, Ruohan | Xi, Shibo | Wu, Jinsong | Zhao, Dongyuan | Mai, L. (Liqiang) | Zhou, Liang
The exploration of efficient, stable, and inexpensive oxygen reduction reaction (ORR) electrocatalysts to replace Pt/C in fuel cells and metal–air batteries still remains an ongoing challenge. Herein, we report an efficient ORR electrocatalyst composed of single-atom FeNₓ and γ-Fe₂O₃ nanoparticle co-functionalized hollow graphitic carbon nanofibers (FeNₓ/Fe₂O₃-CNFs). It is found that the FeNₓ species serve as the active sites, while the γ-Fe₂O₃ nanocrystals function as a co-catalyst to boost the ORR catalytic activity. The obtained FeNₓ/Fe₂O₃-CNFs exhibit desirable ORR electrocatalytic activity with a 4-electron transfer pathway, a half-wave potential of 0.81 V approaching that of commercial Pt/C, low hydrogen peroxide yields (<6% at 0.2–0.7 V), long-term stability (87.14% after 30 000 s), and excellent methanol tolerance. The assembled Zn–air battery based on the FeNₓ/Fe₂O₃-CNFs has an open circuit voltage of 1.51 V and superior energy density of 920 W h kg⁻¹. This work highlights the significant contribution of the co-catalyst in electrocatalysis.
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