2002 Fiscal Year Final Research Report Summary
Deposition of photocatalytic sputtered films for responding to visible light region
| Project/Area Number |
13480176
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
環境保全
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| Research Institution | Toyama University |
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Principal Investigator |
TAKAHASHI Takakaza Toyama University, Faculty of Eng., Associate Professor, 工学部, 助教授 (80019223)
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| Co-Investigator(Kenkyū-buntansha) |
MASUGATA Katsumi Toyama University, Faculty of Eng., Professor, 工学部, 教授 (80157198)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Sputtering / Double-layered film / Photocatalyst / Environmental material / Visible light reaction / Photo semiconductor / Electrochemistry / Disinfecting action |
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| Research Abstract |
The TiO_2 films had anatase crystal structure from the X-ray diffraction patterns and the Raman spectra. The (101), (112), (211) and (220) peaks were observed. With increasing plasma exposure, though the X-ray peak intensities of A(220) increased, the transmittance spectra of the TiO_2 films significantly depended on the wavelength because the TiO_2 films showed semitransparency due to the dim surface. It was found that the crystal structure, the surface morphology and the optical properties of the TiO_2 films were strongly affected by plasma exposure during film deposition.
The WO_3 films with yellow color have been deposited by an rf magnetron sputtering. The film color changed to pale yellow depends on the higher sputtering gas pressure. From the X-ray diffraction patterns, the as-deposited films were polycrystalline crystallizing in the monoclinic crystal structure with high c-axis orientation perpendicular to the film plane. The wavelength at absorption edge is longer than that in TiO_2 and comes in the visible region. The WO_3 films may be used for the underlayer of TiO_2 photocatalyst.
As it has expected that the double layer can adsorb much visible light as compared with TiO_2 single layers, the TiO_2/WO_3 double layers composed of the TiO_2, and WO_3 films were deposited using reactive sputtering in order to study the decomposition of methyl alcohol (CH_3OH) by a photocatalytic reaction. From the measurement of FT-IR transmittance spectra, the CH_3OH can strongly be decomposed into the CO_2 and H_2O molecules as compared to the TiO_2 single layer. When the TiO_2/WO_3 bilayer was irradiated with the artificial sunrays for 130 min, the formation rate of the CO_2 molecules are about two times as fast as that in the TiO_2 single layer. It has been found that the activity of the decomposition of CH_3OH depends on the crystallinity and optical properties of WO_3 underlayers.
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