| Project/Area Number |
10304060
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
機能・物性・材料
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
DOMEN Kazunari CHEMICAL RESOURCES LABORATORY, TOKYO INSTITUTE OF TECHNOLOGY PROFESSOR, 資源化学研究所, 教授 (10155624)
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| Co-Investigator(Kenkyū-buntansha) |
NOMURA Junko CHEMICAL RESOURCES LABORATORY, TOKYO INSTITUTE OF TECHNOLOGY RESEARCH ASSOCIATE, 資源化学研究所, 助手 (60234936)
WADA Akihide CHEMICAL RESOURCES LABORATORY, TOKYO INSTITUTE OF TECHNOLOGY ASSOCIATE PROFESSOR, 資源化学研究所, 助教授 (20202418)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥36,400,000 (Direct Cost: ¥36,400,000)
Fiscal Year 2000: ¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 1999: ¥18,900,000 (Direct Cost: ¥18,900,000)
Fiscal Year 1998: ¥11,800,000 (Direct Cost: ¥11,800,000)
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| Keywords | laser spectroscopy / photoinduced electron transfer / photocatalyst / dye / transient absorption / transient bleaching / recombimation / 電荷移動 / K_4Nb_6O_<17> / 層状化合物 / インターカレーション / 発光寿命 / 光励起 / 緩和過程 / 光触媒 / ソフトケミカル / 層状金属酸化物 / 層剥離 / ラマン分光法 / レーザー分光法 |
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| Research Abstract |
K_4Nb_6O_<17> is known to be a layered photocatalyst to split water into oxygen and hydrogen. The two-dimensional interlayer provides an extremely large area for chemical reactions. Intercalation of suitable dye molecules between the layers achieves visible light response for the photocatalytic reaction. In these cases, charge transfer between the layer and dye molecules is considered to be an important primary process in a whole photocatalytic chemical reaction. By using femtosecond transient absorption spectroscopy, we have investigated ultrafast processes induced by photoexcitation in K_4Nb_6O_<17> and dyeintercalated K_4Nb_6O_<17>. Dynamics of charge carriers generated by bandgap excitation, such as electron-hole recombination and electron transfer was elucidated. The dynamics of Ru(bpy)_3^<2+> intercalated in K_4Nb_6O_<17> was investigated to make clear how fast forward and back electron transfer processes take place.
A broad transient absorption band covering the whole visible reg
… More
ion, which could be ascribed to trapped electrons in K_4Nb_6O_<17>, was observed. The decay was essentially analyzed by second order kinetics, which indicates that the carriers can migrate in the two-dimensional layer and then electron-hole recombination occurs. Long lifetime species surviving longer than nanoseconds was also observed, which would be important for high catalytic reactivity. It the case of the K_4Nb_6O_<17> film intercalated with Ru(bpy)_3^<2+>, transient bleaching of the ground state absorption band of Ru(bpy)_3^<2+> was observed by excitation at 400 nm which cannot excite K_4Nb_6O_<17>. The bleaching of Ru(bpy)_3^<2+> showed fast and non-exponential decay different from that in water. From the fact that this sample shows photocatalytic reactivity under visible light irradiation, electron transfer from Ru(bpy)_3^<2+> should take place by photoexcitation of Ru(bpy)_3^<2+>. Therefore, observed dynamics can be discussed in terms of relatively fast electron transfer and following recombination occurring in the time regions of picosecond and longer than nanosecond.
Ultrafast spectroscopy could successfully reveal some important primary events in the practically used photocatalysts. These results are expected to contribute for design of new catalysts. Less
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