Controllable Growth of Conical and Cylindrical TiO2–Carbon Core–Shell Nanofiber Arrays and Morphologically Dependent Electrochemical Properties

Authors

  • Dr. Rongsheng Chen ,

    1. College of Chemical Engineering and Technology and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (P.R. China), Fax: (+86) 27-68862529
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    • These two authors contributed equally to this work.

  • Liangsheng Hu ,

    1. College of Chemical Engineering and Technology and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (P.R. China), Fax: (+86) 27-68862529
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    • These two authors contributed equally to this work.

  • Prof. Kaifu Huo,

    Corresponding author
    1. College of Chemical Engineering and Technology and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (P.R. China), Fax: (+86) 27-68862529
    • College of Chemical Engineering and Technology and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (P.R. China), Fax: (+86) 27-68862529
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  • Prof. Jijiang Fu,

    1. College of Chemical Engineering and Technology and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (P.R. China), Fax: (+86) 27-68862529
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  • Prof. Hongwei Ni,

    1. College of Chemical Engineering and Technology and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (P.R. China), Fax: (+86) 27-68862529
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  • Prof. Yan Tang,

    1. College of Chemical Engineering and Technology and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (P.R. China), Fax: (+86) 27-68862529
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  • Prof. Paul K. Chu

    1. Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (P.R. China)
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Abstract

Quasi-aligned cylindrical and conical core–shell nanofibers consisting of carbon shells and TiO2 nanowire cores are produced in situ on Ti foils without using a foreign metallic catalyst and template. A cylindrical nanofiber has a TiO2 nanowire core 30–50 nm in diameter and a 5–10 nm-thick cylindrical carbon shell, while in the conical nanostructure the TiO2 nanowire core has a diameter of 20–40 nm and the thickness of the carbon shell varies from about 200 nm at the bottom to about 5 nm at the tip. Electrochemical analysis reveals well-defined redox peaks of the [Fe(CN)6]3−/4− redox couple and heterogeneous charge-transfer rate constants of 0.010 and 0.062 cm s−1 for the cylindrical and conical nanofibers, respectively. The coverage of exposed edge planes on the cylindrical and conical carbon shells is estimated to be 2.5 and 15.5 % respectively. The more abundant exposed edge planes on the conical nanofiber decrease the overpotential and increase the voltammetric resolution during electrochemical detection of uric acid and ascorbic acid. Our results suggest that the density of edge-plane sites estimated from Raman scattering is not necessarily equal to the density of exposed edge-plane sites, and only carbon electrodes with a large density of exposed edge planes or free graphene sheet ends exhibit better electrochemical performance.

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