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  • Iron-Nitrogen-Doped Vertica...
    Yasuda, Satoshi; Furuya, Atom; Uchibori, Yosuke; Kim, Jeheon; Murakoshi, Kei

    Advanced functional materials, February 2, 2016, Letnik: 26, Številka: 5
    Journal Article

    A highly active iron–nitrogen‐doped carbon nanotube catalyst for the oxygen reduction reaction (ORR) is produced by employing vertically aligned carbon nanotubes (VA‐CNT) with a high specific surface area and iron(II) phthalocyanine (FePc) molecules. Pyrolyzing the composite easily transforms the adsorbed FePc molecules into a large number of iron coordinated nitrogen functionalized nanographene (Fe–N–C) structures, which serve as ORR active sites on the individual VA‐CNT surfaces. The catalyst exhibits a high ORR activity, with onset and half‐wave potentials of 0.97 and 0.79 V, respectively, versus reversible hydrogen electrode, a high selectivity of above 3.92 electron transfer number, and a high electrochemical durability, with a 17 mV negative shift of E 1/2 after 10 000 cycles in an oxygen‐saturated 0.5 m H2SO4 solution. The catalyst demonstrates one of the highest ORR performances in previously reported any‐nanotube‐based catalysts in acid media. The excellent ORR performance can be attributed to the formation of a greater number of catalytically active Fe–N–C centers and their dense immobilization on individual tubes, in addition to more efficient mass transport due to the mesoporous nature of the VA‐CNTs. Oxygen reduction reaction activities of a Fe–N–C doped vertically aligned carbon nanotubes catalyst are investigated. Electrochemical measurements in oxygen‐saturated 0.5 m H2SO4 solution demonstrate a high oxygen reduction reaction (ORR) activity (half‐wave potentials of 0.79 V vs reversible hydrogen electrode and 3.92 to 3.98 electron transfer number) and long‐term electrochemical stability, which is the best ORR performance yet reported for a carbon‐nanotube‐based catalyst.