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Nanostructured TiO2 and Its Application in Lithium-Ion Storage

Authors

  • Seung-Taek Myung,

    Corresponding author
    1. Department of Chemical Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan
    2. Department of Nano Engineering and Graphene Research Institute, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747, Korea
    • Department of Chemical Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan
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  • Naohiro Takahashi,

    1. Department of Chemical Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan
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  • Shinichi Komaba,

    1. Department of Applied Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
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  • Chong Seung Yoon,

    1. Department of Materials Science and Engineering, Hanyang University, Seoul 133-79, Korea
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  • Yang-Kook Sun,

    Corresponding author
    1. Department of WCU Energy Engineering & Chemical Engineering, Hanyang University, Seoul 133-79, Korea
    • Department of WCU Energy Engineering & Chemical Engineering, Hanyang University, Seoul 133-79, Korea
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  • Khalil Amine,

    Corresponding author
    1. Electrochemical Technology Program, Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA
    • Electrochemical Technology Program, Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
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  • Hitoshi Yashiro

    1. Department of Chemical Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan
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Abstract

Titania nanorods and nanowires are synthesized via a hydrothermal reaction of amorphous TiO2 in alkaline NaOH, followed by ion exchange in HCl aqueous solution, and dehydration at 400 °C. Although the hydrothermal treatment produces three different particle morphologies depending on the reaction time (nanosheets, nanorods, and nanowires), the products exhibit the same crystal structure. Ion exchange of Na2Ti3O7 in HCl aqueous solution brings about a phase change to H2Ti3O7, but there is no change in the particle morphology. Dehydration of the nanostructured H2Ti3O7 leads to two types of crystal structure—anatase TiO2 for the nanorods, and TiO2–B for the nanowires—although no significant difference is found in the morphology of the products even after dehydration. The nanorods are 40–50 nm in length and 10 nm in diameter, whereas the nanowires are several micrometers in length and tens to hundreds of nanometers in thickness. In-situ X-ray diffraction revealed the formation of anatase TiO2 from the TiO2–B above 450 °C. This finding implies that the phase transformation occurs rather slowly for the TiO2–B nanowires due to the larger particle size and higher crystallinity of H2Ti3O7. Tests with Li-metal half cells indicated that the anatase TiO2 nanorods are more favorable for the storage and release of Li ions because of their greater surface area than the TiO2–B nanowires.

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