| AVS 55th International Symposium & Exhibition | |
| Advanced Surface Engineering | Thursday Sessions |
| Session SE-ThP |
| Session: | Advanced Surface Engineering Poster Session |
| Presenter: | K. Takahashi, University of Toyama, Japan |
| Authors: | S. Biswas, University of Toyama, Japan M.F. Hossain, University of Toyama, Japan M. Shahjahan, University of Toyama, Japan K. Takahashi, University of Toyama, Japan T. Takahashi, University of Toyama, Japan A. Fujishima, Kanagawa Academy of Science and Technology, Japan |
| Correspondent: | Click to Email |
TiO2 is the most widely used photocatalyst for effective decomposition of organic compounds in air and water. However, its technological application is limited by the need for an ultraviolet (UV) excitation source. One of the most promising methods to extend the light-absorbing property of TiO2 and to enhance its photocatalytic efficiency is to couple TiO2 with narrow-bandgap semiconductors, which act as a sensitizer. Tungsten oxide (WO3) with band-gap 2.8 eV, is a promising candidate to be used as under-layer for TiO2 photocatalysts. However, WO3 should have some amount of uncovered surface so that it can act as a reducing agent. In this study, WO3 films were deposited on glass substrates, using facing target dc reactive sputtering technique and the upper TiO2 thin films were also deposited with the same technique using different masks to leave various amounts of WO3-exposed surfaces: 0%, 30% and 80%. The crystallographic properties, surface structures and optical properties of WO3 films were investigated in detail. The X-ray diffraction patterns show triclinic and anatase crystal structure for the WO3 films and TiO2 films, respectively. The optical and surface morphological properties of both WO3 and TiO2 layers have been studied using UV-visible spectrometer, field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The photocatalytic activity was measured by the rate of photodecomposition of methanol in UV and visible light irradiation, evaluated by Fourier transform infrared spectrometer (FTIR). The results show that with the variation of WO3 exposed area, photocatalytic activity of WO3/ TiO2 system varies significantly. It is revealed that, with the increase of WO3-exposed surface photocatalytic activity increases initially, but it decreases with the further increase. The result has been tried to be explained on the basis of methanol-photodecomposition mechanism and the amount of relative exposed surface of WO3 and TiO2.