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Promoted oxygen reduction kinetics on nitrogen-doped hierarchically porous carbon by engineering proton-feeding centers

  • Chen, Guangbo
  • Wang, Tao
  • Liu, Pan
  • Liao, Zhongquan
  • Zhong, Haixia
  • Wang, Gang
  • Zhang, Panpan
  • Yu, Minghao
  • Zschech, Ehrenfried
  • Chen, Mingwei
  • Zhang, Jian
  • Feng, Xinliang
Publication Date
Jan 01, 2020
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Electrocatalytic oxygen reduction reaction (ORR) is the vital process for next-generation electrochemical energy storage and conversion technologies, e.g., metal-air batteries and fuel cells. During the ORR, the O-2* and O* intermediates principally combine with protons to form OOH* and OH* species, respectively, which are the proton-coupled electron transfer processes. Unfortunately, under alkaline conditions, the protons are essentially generated from the sluggish water dissociation process, which unavoidably limits the ORR kinetics. Herein, we design and synthesize a nitrogen-doped hierarchically porous carbon with homogeneously distributed ultrafine alpha-MoC nanoparticles (alpha-MoC/NHPC) as a model electrocatalyst. Theoretical investigations unveil that alpha-MoC on NHPC could efficiently reduce the energy barrier of the water dissociation process to generate protons, eventually promoting the proton-coupled ORR kinetics. In a 0.1 M KOH aqueous solution, alpha-MoC/NHPC exhibits excellent ORR performance with a high half-wave potential of 0.88 V (vs. reversible hydrogen electrode), which outperforms those for NHPC and commercial Pt/C. Moreover, as the air electrode in a zinc-air battery, alpha-MoC/NHPC presents a large peak power density of 200.3 mW cm(-2)and long-term stability. Thereby, our approach to engineering proton-feeding centers paves a new avenue towards the understanding of ORR kinetics and the development of high-performance ORR electrocatalysts.

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