Oxalic acid sensors based on sol–gel nanostructured TiO2 films
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Titanium (IV) oxide semiconducting layers were prepared by means of the templated sol–gel method and deposited on conductive ITO substrates. The films were described by a series of techniques involving X-ray diffraction (XRD), Raman spectroscopy, X-ray reflectivity (XRR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and ultraviolet–visible spectroscopy (UV–Vis). The photo-excitation properties of the films were characterized by electrochemical tests and evaluated from the obtained polarization curves. The generated photocurrents were measured in the presence of the hole-scavengers—oxalic acid and formic acid in the electrolyte. It was shown that especially in the case of oxalic acid the developed system can be used as an efficient and simpler concentration sensor. The relationship between values of the generated photocurrent and the layers’ thicknesses was also investigated.
KeywordsTitanium oxide Photo-electrochemical oxidation Oxalic acid Formic acid Sol–Gel
This work was financially supported by Academy of Sciences of the Czech Republic. The authors also gratefully acknowledge the Grant Agency of the Czech Republic, project No. GD 203/08/H032 and GA 104/09/0694, and Academy of Sciences of the Czech Republic—project No. KAN400720701. The authors thank Mgr. Z. Matěj, Charles University in Prague, for XRD and XRR measurements.
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