Enhanced effect and mechanism of SiO2 addition in super-hydrophilic property of TiO2 films

Relationship between the effect and the amount of SiO2 addition on the photo-generated hydrophilicity of TiO2 films is investigated. X-ray diffraction, UV–Vis spectrum and Fourier transform infrared spectroscopy are used to determine film behavior and the hydrophilicity is assessed by contact angle measurement. It is found that addition of 40 mol% SiO2 to TiO2 is most effective for reducing the contact angle of water. The contact angle of water can maintain low for a long time in dark place. SiO2 addition has a suppressive effect on the crystal growth of TiO2 in calcination and enhances the transmittance of the composite films. SiO2 and TiO2 form single oxide particles in the films, but a part of complex oxide may be formed. TiOSi bonds increase the acidity which induces the increasing of the hydroxyl content in the composite films.