The Effects of Preparation Conditions for a BaNbO2N Photocatalyst on Its Physical Properties

Authors

  • Dr. Takashi Hisatomi,

    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)
    2. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
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  • Chisato Katayama,

    1. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
    2. FUJIFILM Corporation, 577, Ushijima, Kaisei-Machi, Ashigarakami-gun, 258-8577 Kanagawa (Japan)
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  • Dr. Kentaro Teramura,

    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)
    2. Current address: Department of Molecular Engineering, Kyoto University, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)
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  • Dr. Tsuyoshi Takata,

    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)
    2. Current address: Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba-shi, Ibaraki 305-0047 Japan.
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  • Dr. Yosuke Moriya,

    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)
    2. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
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  • Dr. Tsutomu Minegishi,

    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)
    2. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
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  • Dr. Masao Katayama,

    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)
    2. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
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  • Dr. Hiroshi Nishiyama,

    1. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
    2. Department of Chemical System Engineering, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
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  • Dr. Taro Yamada,

    1. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
    2. Department of Chemical System Engineering, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
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  • Prof. Dr. Kazunari Domen

    Corresponding author
    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)
    2. Japan Technological Research Association of Artificial, Photosynthetic Chemical Process (ARPChem), 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8589 Chiba (Japan)
    • Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo (Japan)===

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Abstract

BaNbO2N is a semiconductor photocatalyst active for water oxidation under visible-light irradiation up to λ=740 nm. It is important to understand the nitridation processes of precursor materials to form BaNbO2N to tune the physical properties and improve the photocatalytic activity. Comprehensive experiments and analyses of temperatures, durations, ammonia flow rates, and barium/niobium ratios in the precursor during the nitridation process reveals that faster ammonia flow rates and higher barium/niobium ratios in the precursors help to suppress reduction of pentavalent niobium ions in the nitridation products and that the use of a precursor prepared by a soft-chemistry route allows the production of BaNbO2N at lower temperatures in shorter times than the use of physical mixtures of BaCO3 and Nb2O5 because the niobium species is dispersed among the barium species. BaNbO2N prepared by the soft-chemistry route exhibits comparatively higher activity than that prepared from physical mixtures of BaCO3 and Nb2O5, probably because of lower nitridation temperatures, which suppress excessive dissociation of ammonia, and thereby reduce pentavalent niobium ions, and intimate interaction of niobium and barium sources, which lowers the densities of mid-gap states associated with defects.

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