Ultrathin SiOx Film Coating Effect on the Wettability Change of TiO2 Surfaces in the Presence and Absence of UV Light Illumination
✍ Scribed by Akihiko Hattori; Tetsuro Kawahara; Takashi Uemoto; Fumiaki Suzuki; Hiroaki Tada; Seishiro Ito
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 113 KB
- Volume
- 232
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
Wettability of sol-gel TiO 2 film surfaces has been studied by following the H 2 O contact angle (θ) as functions of illumination time and subsequent dark storage time. Upon illumination of the TiO 2 surface (λ ex > 300 nm), the value of θ rapidly decreased to reach approximately zero (photoprocess). When the resultant superhydrophilic sample was stored in the dark, the θ value increased slowly with increasing storage time (dark process). Ultrathin SiO x films were formed on the surface of TiO 2 by repeating chemisorption of 1,3,5,7-tetramethylcyclotetrasiloxane and its photooxidation. With increasing thickness of the SiO x monolayer coating, the rate for the dark process significantly decreased, while that for the photoprocess also decreased. Both Xray photoelectron spectroscopic studies and product analyses during the photoprocess clarified that photocatalytic oxidation of organic adsorbates in air causes the superhydrophilicity of the TiO 2 surfaces.