가시광 활성 WO3-TiO2 복합체 광촉매의 제조 및 이의 특성 평가
Preparation of WO3-TiO2 Photocatalyst and Evaluation of Its Photo-activity in the Visible Light Range
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The most general photocatalyst, TiO2 and WO3, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with TiO2 and WO3. In the TiO2-WO3 composite, WO3 absorbs visible light creating excited electrons and holes while some of the excited electrons move to TiO2 and the holes remain in WO3. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor,retarding the recombination rate of excited electrons and holes. In making a mixture of TiO2-WO3 composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of TiO2(4) and WO3(6) shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.
Abstract
The most general photocatalyst, TiO2 and WO3, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with TiO2 and WO3. In the TiO2-WO3 composite, WO3 absorbs visible light creating excited electrons and holes while some of the excited electrons move to TiO2 and the holes remain in WO3. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor,retarding the recombination rate of excited electrons and holes. In making a mixture of TiO2-WO3 composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of TiO2(4) and WO3(6) shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.
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