Spectral and photocatalytic characteristics of TiO₂ CVD films on quartz

A series of novel CVD films of titanium(IV) oxide of different thicknesses, spanning the range 10–91 nm, are prepared on quartz, via the reaction of titanium(IV) chloride and ethyl acetate, using a CVD technique. The films are clear, mechanically robust and comprise thin layer of nanocrystalline anatase titania of different thicknesses that absorb UV light. The UV–Visible spectral profiles of all the CVD TiO₂ films of different thickness are the same and obey Lambert’s law (absorbance ∝ film thickness). A plot of the reciprocal length for the TiO₂ coating versus wavelength is reported. The photocatalytic activity of each film to mediate the destruction of a thin layer of stearic acid is investigated. The rate depends directly upon the fraction of light absorbed and the apparent quantum yield for the overall process is 0.00035, which appears low compared with that for sol–gel TiO₂ films.