Unravelling the Structure of Electrocatalytically Active Fe–N Complexes in Carbon for the Oxygen Reduction Reaction

Authors

  • Yansong Zhu,

    1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning, 110016 (China)
    2. School of Chemistry and Life Science, Anshan Normal University, Anshan, Liaoning, 114005 (China)
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  • Bingsen Zhang,

    1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning, 110016 (China)
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  • Xin Liu,

    1. Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023 (China)
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  • Da-Wei Wang,

    1. School of Chemical Engineering, UNSW Australia, UNSW Sydney, NSW 2052 (Australia)
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  • Prof. Dang Sheng Su

    Corresponding author
    1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning, 110016 (China)
    • Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning, 110016 (China)

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  • The authors acknowledge the financial support from MOST (2011CBA00504), NSFC of China (21133010, 21203215, 51221264, 21261160487), and ‘Strategic Priority Research Program’ of the Chinese Academy of Sciences, Grant No. XDA09030103.

Abstract

Non-precious Fe/N co-modified carbon electrocatalysts have attracted great attention due to their high activity and stability in oxygen reduction reaction (ORR). Compared to iron-free N-doped carbon electrocatalysts, Fe/N-modified electrocatalysts show four-electron selectivity with better activity in acid electrolytes. This is believed relevant to the unique Fe–N complexes, however, the Fe–N structure remains unknown. We used o,m,p-phenylenediamine as nitrogen precursors to tailor the Fe–N structures in heterogeneous electrocatalysts which contain FeS and Fe3C phases. The electrocatalysts have been operated for 5000 cycles with a small 39 mV shift in half-wave potential. By combining advanced electron microscopy and Mössbauer spectroscopy, we have identified the electrocatalytically active Fe–N6 complexes (FeN6, [FeIII(porphyrin)(pyridine)2]). We expect the understanding of the FeN6 structure will pave the way towards new advanced Fe–N based electrocatalysts.

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