AVS 49th International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeP

Paper TF-WeP14
Photocatalytic Properties of TiO@sub2@/WO@sub3@ Bilayers Deposited by Reactive Sputtering

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Poster Session
Presenter: T. Takahashi, Toyama University, Japan
Authors: T. Takahashi, Toyama University, Japan
H. Nakabayashi, Toyama University, Japan
J. Tanabe, Toyama University, Japan
N. Yamada, Toyama University, Japan
Correspondent: Click to Email
Titanium dioxide (TiO@sub2@) has attracted considerable attention because it is known to have strong activity as a photocatalyst under irradiation of ultraviolet rays. However, TiO@sub2@ photocatalyst can only react slightly to solar energy because of its optical band gap E@subG@ smaller than 3.2 eV (@lambda@ of 380 nm). So, it is desirable for most solar energy applications to have new materials that can highly react strongly to visible-light. In this study, the bilayers composed of TiO@sub2@ and WO@sub3@ films have been prepared by reactive sputtering at room temperature. At first, TiO@sub2@ films with a thickness of about 1.4 µm have been deposited on glass-slide substrates at working gas pressure P@subW@ of 1 mTorr and a mixed atmosphere of Ar and O@sub2@, using the facing targets sputtering with dc power supply. Then WO@sub3@ films have been deposited onto as-deposited TiO@sub2@ ones at various P@subW@ ranging from 1 to 8 mTorr in an atmosphere of mixture gas of 80%Ar and 20%O@sub2@, using RF magnetron sputtering. The gaseous methyl alcohol by using the bilayers have been decomposed under irradiation with artificial sunrays of wavelength @lambda@ ranging from 330 to 750 nm for 2 h at room temperature. The bilayers were successful in carrying out a photocatalytic reaction of the decomposition of CH@sub3@OH into CO@sub2@ and H@sub2@O from measurement of infrared transmittance spectra. Its decomposition rate using the bilayers significantly increases, as compared with that using the monolayers of TiO@sub2@ films. It is found that the bilayers can decompose CH@sub3@OH under irradiation of only slight visible-light. Consequently, the bilayers deposited in this study have a good photocatalytic reaction and activate the decomposition of gaseous methyl alcohol.