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Unbiased Photoelectrochemical Water Splitting in Z-Scheme Device Using W/Mo-Doped BiVO4 and ZnxCd1−xSe

Authors

  • Dr. Hyun S. Park,

    1. Center for Electrochemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712 (USA)
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  • Dr. Heung Chan Lee,

    1. Center for Electrochemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712 (USA)
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  • Dr. Kevin C. Leonard,

    1. Center for Electrochemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712 (USA)
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  • Dr. Guanjie Liu,

    1. Center for Electrochemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712 (USA)
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  • Prof. Dr. Allen J. Bard

    Corresponding author
    1. Center for Electrochemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712 (USA)
    • Center for Electrochemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712 (USA)

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Abstract

Photoelectrochemical water splitting to generate H2 and O2 using only photon energy (with no added electrical energy) has been demonstrated with dual n-type-semiconductor (or Z-scheme) systems. Here we investigated two different Z-scheme systems; one is comprised of two cells with the same metal-oxide semiconductor (W- and Mo-doped bismuth vanadate), that is, Pt-W/Mo-BiVO4, and the other is comprised of the metal oxide and a chalcogenide semiconductor, that is, Pt-W/Mo-BiVO4 and Zn0.2Cd0.8Se. The redox couples utilized in these Z-scheme configurations were I/IO3 or S2−/Sn2−, respectively. An electrochemical analysis of the system in terms of cell components is shown to illustrate the behavior of the complete photoelectrochemical Z-scheme water-splitting system. H2 gas from the unbiased photolysis of water was detected using gas chromatography–mass spectroscopy and using a membrane-electrode assembly. The electrode configuration to achieve the maximum conversion efficiency from solar energy to chemical energy with the given materials and the Z-scheme is discussed. Here, the possibilities and challenges of Z-scheme unbiased photoelectrochemical water-splitting devices and the materials to achieve practical solar-fuel generation are discussed.

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