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Morphological, structural, and photoelectrochemical characterization of n-type Cu2O thin films obtained by electrodeposition

Authors

  • Paula Grez,

    Corresponding author
    1. Instituto de Química, Pontificia Universidad Católica de Valparaíso, Avda. Universidad 330, Curauma, Placilla, Valparaíso Casilla, 4059 Valparaíso, Chile
    • Phone: +56-32-2274993, Fax: +56-32-2274939
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  • Francisco Herrera,

    1. Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Avenida Libertador Bernardo O'Higgins n° 3363, Estación Central, Santiago, Chile
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  • Gonzalo Riveros,

    1. Departamento de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Avenida Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
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  • Andrés Ramírez,

    1. Instituto de Química, Pontificia Universidad Católica de Valparaíso, Avda. Universidad 330, Curauma, Placilla, Valparaíso Casilla, 4059 Valparaíso, Chile
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  • Rodrigo Henríquez,

    1. Instituto de Química, Pontificia Universidad Católica de Valparaíso, Avda. Universidad 330, Curauma, Placilla, Valparaíso Casilla, 4059 Valparaíso, Chile
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  • Enrique Dalchiele,

    1. Instituto de Física, Facultad de Ingeniería, Universidad de la República, Herrera y Reissig 565, C.C. 30, 11000 Montevideo, Uruguay
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  • Ricardo Schrebler

    1. Instituto de Química, Pontificia Universidad Católica de Valparaíso, Avda. Universidad 330, Curauma, Placilla, Valparaíso Casilla, 4059 Valparaíso, Chile
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Abstract

Thin films of copper(I) oxide (Cu2O) were electrodeposited on fluorine-doped tin oxide predeposited glass substrates, by reduction of Cu2+ from Cu(II) acetate acid aqueous solutions. The Cu2O was potentiostatically grown at a potential value of −0.450 V (vs. SMSE) at 70 °C. The Cu2O thin films were characterized by means of scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), optical transmission, electrochemical impedance spectroscopy, and photoelectrochemical experiments. Through these techniques, it was possible to establish the cubic Cu2O phase with a high crystallinity and a strong preferential growth along the [200] and [220] directions. Cu2O thin films show oxygen vacancies with formation of a nonstoichiometric compound with the presence of Cu(0) in the crystal lattice as determined by XPS analysis. In addition, Cu2O was used as the photoanode for the I oxidation reaction when the system was illuminated (Φ0 = 50.0 mW cm−2). The films exhibited a clear n-type semiconductor behavior, which was in agreement with the Mott–Schottky results. This behavior was explained by considering the nonstoichiometry of the oxide.

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