Combined local anodization of titanium and scanning photoelectrochemical mapping of TiO2 spot arrays

Localized growth of TiO2 and rapid screening of TiO2 photoelectrochemical properties by scanning electrochemical microscopy (SECM) are described. We report the fabrication and operation of an electrochemical tool comprising a microcapillary and an ultramicroelectrode (Cap-UME) that is used for the local formation of TiO2 microspots. The tip allows the generation of arrays of TiO2 of different physicochemical and catalytic characteristics. Moreover, these results prove that local anodization is an efficient method to obtain TiO2 films with micrometre resolution. The use of a combined optical fiber-ultramicroelectrode (OF-UME) in a SECM configuration may operate in two different detection modes. In the first mode, the array is biased and the OF-UME is used as a scanning light source allowing a photocurrent mapping of the surface. In the second mode, the dual OF-UME system serves simultaneously as a light source and an O2 electrochemical sensor which resolved spatially the photoelectrochemically generated O2 species. A direct correlation between the potentials used to produce TiO2, the photocatalytic properties of the TiO2 spots and the amount of oxygen produced was found, demonstrating the strong potential of these tools for the rapid and convenient mapping of TiO2 array properties on a single surface.

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