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Surface Properties of Anatase TiO2 Nanowire Films Grown from a Fluoride-Containing Solution

Authors

  • Dr. Thomas Berger,

    Corresponding author
    1. Departamento de Sistemas Físicos, Químicos y Naturales, Área de Química Física, Universidad Pablo de Olavide, Ctra. Utrera, km 1, 41013 Sevilla (Spain)
    • Departamento de Sistemas Físicos, Químicos y Naturales, Área de Química Física, Universidad Pablo de Olavide, Ctra. Utrera, km 1, 41013 Sevilla (Spain)
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  • Dr. Juan A. Anta,

    1. Departamento de Sistemas Físicos, Químicos y Naturales, Área de Química Física, Universidad Pablo de Olavide, Ctra. Utrera, km 1, 41013 Sevilla (Spain)
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  • Dr. Víctor Morales-Flórez

    1. Instituto de Ciencia de Materiales de Sevilla, CSIC-Universidad de Sevilla, Av. Américo Vespucio, 49, 41092 Sevilla (Spain)
    2. Departamento de Física de la Materia Condensada, Universidad de Sevilla, Av. Reina Mercedes, s/n, 41012 Sevilla (Spain)
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Abstract

Controlling the surface chemistry of nucleating seeds during wet-chemical synthesis allows for the preparation of morphologically well-defined nanostructures. Synthesis conditions play a key role in the surface properties, which directly affect the functional properties of the material. Therefore, it is important to establish post-synthesis treatments to facilitate the optimization of surface properties with respect to a specific application, without losing the morphological peculiarity of the nanostructure. We studied the surface properties of highly crystalline and porous anatase TiO2 nanowire (NW) electrodes, grown by chemical-bath deposition in fluoride-containing solutions, using a combined electrochemical and spectroscopic approach. As-deposited films showed low capacity for catechol adsorption and a poor photoelectrocatalytic activity for water oxidation. Mild thermal annealing at 200 °C resulted in a significant improvement of the electrode photoelectrocatalytic activity, whereas the bulk properties of the NWs (crystal structure, band-gap energy) remained unchanged. Enhancement of the functional properties of the material is discussed on the basis of adsorption capacity and electronic properties. The temperature-induced decrease of recombination centers, along with the concomitant increase of adsorption and reaction sites upon thermal annealing are called to be responsible for such improved performance.

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