Photoreduction of Water by using Modified CuInS2 Electrodes

Authors

  • Prof. Shigeru Ikeda,

    Corresponding author
    1. Research Center for Solar Energy Chemistry, Osaka University, 1–3 Machikaneyama, Toyonaka 560–8531 (Japan), Fax: (+81) 6 6850 6699
    • Research Center for Solar Energy Chemistry, Osaka University, 1–3 Machikaneyama, Toyonaka 560–8531 (Japan), Fax: (+81) 6 6850 6699
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  • Takayuki Nakamura,

    1. Research Center for Solar Energy Chemistry, Osaka University, 1–3 Machikaneyama, Toyonaka 560–8531 (Japan), Fax: (+81) 6 6850 6699
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  • Sun Min Lee,

    1. Research Center for Solar Energy Chemistry, Osaka University, 1–3 Machikaneyama, Toyonaka 560–8531 (Japan), Fax: (+81) 6 6850 6699
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  • Tetsuro Yagi,

    1. Research Center for Solar Energy Chemistry, Osaka University, 1–3 Machikaneyama, Toyonaka 560–8531 (Japan), Fax: (+81) 6 6850 6699
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  • Dr. Takashi Harada,

    1. Research Center for Solar Energy Chemistry, Osaka University, 1–3 Machikaneyama, Toyonaka 560–8531 (Japan), Fax: (+81) 6 6850 6699
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  • Dr. Tsutomu Minegishi,

    1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
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  • Prof. Michio Matsumura

    1. Research Center for Solar Energy Chemistry, Osaka University, 1–3 Machikaneyama, Toyonaka 560–8531 (Japan), Fax: (+81) 6 6850 6699
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Abstract

Polycrystalline CuInS2 films were fabricated by sulfurization of electrodeposited Cu and In metallic precursor films. Structural analyses revealed that the CuInS2 film formed compact agglomerates of crystallites with grain sizes of ca. 0.5–1.5 μm. Photoelectrochemical characterization revealed that the film was p-type with a flat band potential of 0.3–0.4 V (vs Ag/AgCl at pH 4), which is suitable for water reduction but cannot be for water oxidation. Upon loading Pt deposits, the film worked as a hydrogen (H2) liberation electrode under cathodic polarization. Moreover, by introduction of n-type thin layers such as CdS and ZnS on the CuInS2 surface before the Pt loading, appreciable improvements of H2 liberation efficiency were achieved: for the CdS modified sample, spectral response data showed incident photon to current efficiency as high as 20 % at wavelengths ranging from ca. 500 to 750 nm. Appreciable H2 evolution on this sample under potentials of power-producing regions was also confirmed.

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