Product Code: ICA12_P162

Variation of Photocatalytic Activity in Titanium Dioxide Film Modified by Femtosecond Laser Irradiation
Authors:
Naoto Horiguchi, Graduate School of Engineering, Osaka Univ.; Osaka Japan
Masahiro Tsukamoto, Joining and Welding Research Institute, Osaka Univ.; Ibaraki, Osaka Japan
Minoru Yoshida, School of Science and Engineering, Kinki Univ.; Higashiosaka, Osaka Japan
Togo Shinonaga, Graduate School of Engineering, Osaka Univ.; Suita, Osaka Japan
Masanari Takahashi, Osaka Municipal Technical Research Institute; Joto-Ku, Osaka Japan
Masayuki Fujita, Institute for Laser Technology; Suita, Osaka Japan
Nobuyuki Abe, Joining and Welding Research Institute, Osaka Univ.; Ibaraki, Osaka Japan
Presented at ICALEO 2012

Titanium dioxide (TiO2) has photocatalytic activity and disassembles the toxic substance in the air by ultraviolet (UV) light illumination. However, most UV lights cannot be found in the room interior. Therefore development of the visible light-activated TiO2 photocatalyst is required for the purpose of indoor use. In our previous study, we fabricated TiO2 films with an aerosol beam and the films were irradiated with femtosecond laser. Although TiO2 films were darkened after the laser irradiation, laser ablation did not occur. It is reported that oxygen deficiencies in TiO2 might be the cause for the darkening. Oxygen deficiencies might create a donor level between conduction and valence bands. There is a possibility that TiO2 film modified by the femtosecond laser irradiation shows a visible light sensitivity. In this study, we investigated variation of the photocatalytic activity of TiO2 films after the femtosecond laser irradiation. The wavelength, the pulse width and the repetition rate of the femtosecond laser were 775 nm, 150 fs and 1kHz, respectively. In the experiment, the laser spot was scanned on the TiO2 film surface and the laser fluence was changed within the laser fluence range in which the laser ablation was not caused and morphology of the TiO2 film surface was not varied.　 The photocatalytic activity of TiO2 films was evaluated with acetaldehyde reaction under UV and visible light illumination. TiO2 film darkened by the femtosecond laser irradiation had photocatalytic activity under visible light.