Photoinduced hydrophilicity of TiO2/WO3 double layer films

The photoinduced hydrophilicity of TiO2/WO3 double layer films fabricated by conventional RF magnetron sputtering was evaluated. The photoinduced hydrophilic reaction at the TiO2 surface during irradiation by a 10 W cylindrical fluorescent light bulb was enhanced by the presence of WO3 under the TiO2 layer. However, when the TiO2 and WO3 layers were separated by an insulating layer, the surface did not become highly hydrophilic under the same light conditions. The enhanced photoinduced hydrophilic reaction can be explained by charge transfer between the TiO2 and WO3 layers. TiO2/WO3 double layer films may be applied as coatings on indoor products requiring antifogging and self-cleaning properties because the films produce a highly hydrophilic surface even with indoor lights.