Fluorinated titania

Light-induced transformations over fluorinated titania (TiOi/F) cannot be initiated either by =Ti— 0 (OHads), due to the lack of =Ti—OH groups, or by SET from a surface complexed substrate, due to the fluoride competition. In addition to these major effects, the adsorption of molecular oxygen can be affected also and the surface charge is dramatically decreased. The last effect may be important particularly for charged substrates and intermediates and for the possibility of interfacial electron transfer. 

It is known from decades, particularly for Al, that porous oxide layers can be grown by anodization typically in acidic electrolytes, while anodization in neutral electrolytes typically leads to a compact oxide layer. However, Masuda et al were the first who showed that a very high degree of order can be achieved for these porous geometries. Zwilling et first reported the porous surface of titania films electrochemically formed in fluorinated electrolyte by titanium anodization, but only a decade later Grimes et al. showed that the nanostructure is constituted by uniform titania nanotube arrays. 

Usually the nanotube arrays have been made from a titanium thick film or foil, in which case the resulting nanotubes rest upon an underlying Ti substrate as separated by a barrier layer. The nanotube arrays have also been fabricated from a titanium thin film sputtered onto a variety of substrates, such as silicon and fluorine doped tin oxide (FTO) coated conductive glass. This extends the possibility for preparing technical catalysts by deposing a thin Ti layer over a substrate (a foam, for example) and then inducing the formation of the nanostructured titania film by anodic oxidation. ... 

Minero, C. Aliberti, C. Pelizzetti, E. Terzian, R. Serpone, N. Kinetic studies in heterogeneous photocatalysis. 6. AMI simulated sunlight photodegradation over titania in aqueous media A first case of fluorinated aromatics and identification of intermediates, Langmuir 1991, 7, 928. 

Ti02 C.L titania compact layer that is obtained by anodization in fluorine-free... 

The dye-sensitized solar cell (DSC), often called the Gratzel cell, is constructed as follows. A layer of titania paste consisting of anatase nanoparticles is spread onto a glass plate that is coated with a thin conducting layer of fluorine-doped Sn02. The paste contains organic binders that are removed when the film is calcined in air (typically at 450-500 °C), leaving a mesoporous titania film (ca. 10 pm thick) with a porosity of around 50 %. The titania film is immersed in... 

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