title: Surface properties of anatase TiO2 nanowire films grown from a fluoride-containing solution.
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.
authors.affiliation: Departamento de Sistemas Físicos, Químicos y Naturales, Área de Química Física, Universidad Pablo de Olavide, Ctra. Utrera, km 1, 41013 Sevilla, Spain. tberger@upo.es
authors.forename: Thomas
authors.initials: T
authors.lastname: Berger
authors.forename: Juan A
authors.initials: JA
authors.lastname: Anta
authors.forename: Víctor
authors.initials: V
authors.lastname: Morales-Flórez