Proton Conductivities of Graphene Oxide Nanosheets: Single, Multilayer, and Modified Nanosheets

Authors

  • Kazuto Hatakeyama,

    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
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  • Mohammad Razaul Karim,

    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
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  • Chikako Ogata,

    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
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  • Hikaru Tateishi,

    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
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  • Dr. Asami Funatsu,

    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
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  • Prof. Takaaki Taniguchi,

    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
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  • Prof. Michio Koinuma,

    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
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  • Prof. Shinya Hayami,

    Corresponding author
    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
    • Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)

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  • Prof. Yasumichi Matsumoto

    Corresponding author
    1. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
    2. JST, CREST, Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 (Japan)
    • Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)

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Abstract

Proton conductivities of layered solid electrolytes can be improved by minimizing strain along the conduction path. It is shown that the conductivities (σ) of multilayer graphene oxide (GO) films (assembled by the drop-cast method) are larger than those of single-layer GO (prepared by either the drop-cast or the Langmuir-Blodgett (LB) method). At 60 % relative humidity (RH), the σ value increases from 1×10−6 S cm−1 in single-layer GO to 1×10−4 and 4×10−4 S cm−1 for 60 and 200 nm thick multilayer films, respectively. A sudden decrease in conductivity was observed for with ethylenediamine (EDA) modified GO (enGO), which is due to the blocking of epoxy groups. This experiment confirmed that the epoxide groups are the major contributor to the efficient proton transport. Because of a gradual improvement of the conduction path and an increase in the water content, σ values increase with the thickness of the multilayer films. The reported methods might be applicable to the optimization of the proton conductivity in other layered solid electrolytes.

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