Title : Spectroscopic investigation of the influence of UV-irradiation on hydroxyl-hydrated layer of TiO2 photocatalyst
Applications to environmental cleanup have been one of the most significant areas in heterogeneous photocatalysis for a long time.
Titanium dioxide is the most widely used photocatalyst, which provides the most reasonable trade-off between photocatalytic performance, stability in broad variety of chemical environments, low price, and essential low toxicity.
FT-IR spectroscopy is well known as useful technique for study of adsorbed species. This method is especially sensitive to water molecules and superficial OH-groups, though the spectral line broadening due to H-bonding (in the case of high surface coverage) makes the interpretation somewhat difficult.
In our experiments, powdered samples were pressed into the self-supported pellets with the thickness of about 0.1 mm, and outgassed at elevated temperatures in vacuum followed by the annealing in the presence of oxygen for removal of organic impurities. Then, experiments were carried out at ambient temperature.
In present work, the influence of UV-radiation applied to powdered TiO2 samples was investigated spectroscopically under vacuum conditions (~3E-6 torr). Experiments were performed in-situ at different stages of surface hydration for simulation of the case of superhydrophylic self-cleaning films at ambient conditions. Surface species formed were detected and analysed. Mechanisms of the hydroxy-hydrated layer reconstruction being under the action of UV-Vis radiation were considered.