Titanium dioxide (TiO 2 ) thin films are synthesized using aerosol-assisted (AA)CVD of titanium (IV) isopropoxide (TTIP) in methanol. Deposition is carried out on glass, steel, and titanium substrates at 400-5508C. The films produce morphologies that are radically different to those from typical aerosol-assisted processes, and from the use of TTIP in low or atmospheric pressure (AP)CVD. The films show some substrate-dependent morphology and properties. In particular at 5508C the films on steel show needle-and rod-like particles. X-ray diffraction (XRD) and Raman spectroscopy of the TiO 2 films show that on steel or titanium substrates only the rutile form can be obtained, whereas on glass either anatase, anatase/rutile mixtures, or rutile can be obtained, depending on substrate temperature. The TiO 2 films formed at 5508C on all substrates are hydrophobic to water droplets, with contact angles in the range 101-1108. These films become hydrophilic on heating to above 1008C in air, or superhydrophillic when irradiated under 254 nm radiation generating water-contact angles less than 58. Surprisingly, use of TTIP under APCVD on steel substrates without an aerosol form exclusively the anatase form of TiO 2 at 400-5508C, whereas use of a methanolic aerosol delivery system for the TTIP forms rutile. Hence use of the methanol aerosol has a controlling influence on the deposition chemistry. The TiO 2 thin films are shown to be active photocatalysts using a dye-ink test, and are also shown to be able to photo-split water in a sacrificial system to evolve oxygen.

Titanium (IV) isopropoxide (TTIP) in methanol, ethanol, hexane, dichloromethane, and isopropanol solvents is used to deposit titanium dioxide thin films on glass and steel substrates at 550 8C using aerosol-assisted (AA)CVD. X-ray diffraction (XRD), and Raman spectra of the as-deposited films show that using methanol as the carrier solvent produces exclusively rutile films on steel, and predominantly rutile on glass substrates, while the use of the other solvents produces exclusively anatase phase on the steel under the same conditions. TiO 2 is also deposited by AACVD from a mixture of ethanol and methanol solvents. As little as 15% of methanol in ethanol produces rutile as the predominant phase. Using a dye-ink test, the titanium dioxide thin films produced with ethanol are shown to be more active photocatalysts than films produced with methanol. All the films show photoinduced superhydrophilicity but, surprisingly, films stored in the dark have a water contact angle above 1008.