Photocatalytic activity of needle-like TiO2/WO3−x thin films prepared by chemical vapour deposition

The enhanced photocatalytic activity of needle-like TiO2/WO3−x (0 < x ≤ 0.3) composite thin films is demonstrated in the degradation of stearic acid, a model system for the organic pollutants typically present on window surfaces. The films were synthesised by atmospheric pressure chemical vapour deposition (APCVD) from reaction of tungsten and titanium chlorides with ethanol and ethyl acetate as oxygen sources, respectively, and characterised by X-ray diffraction, Raman spectroscopy, SEM and AFM. The increase in activity of films is explained in terms of an effective vectorial charge separation at the interface of the two oxide semiconductors. The interaction of water with the surface of the TiO2/WO3−x composite film is also discussed after water droplet contact angle measurements.