Oxygen plasma induced hydrophilicity of TiO2 thin films

Anatase nano-TiO2 thin films were fabricated by reactive magnetron sputtering metal Ti target followed by thermal annealing in air at 450 °C for 2 hrs. The crystalline structure of the sample films were characterized by X-ray diffraction (XRD) and the hydrophilicity was characterized with the diameters of 1 μl water drop. The films were irradiated by oxygen plasmas and the effects of the radio frequency (rf) power, the gas pressure and the irradiation time of the oxygen plasmas on the hydrophilicity of the TiO2 thin films were investigated. Hydrophilicity can be induced by oxygen plasmas and further more the hydrophilicity shows high stability whenever under the natural light or in dark.

► Optimized irradiation parameters were suggested for oxygen plasma induced hydrophilicity of TiO2 thin films. ► Highly stable hydrophilicity of TiO2 thin films were obtained by oxygen plasma irradiation. ► New mechanism was suggest that oxygen atoms absorbed on the surface may help to keep the hydrophilicity.