| Project/Area Number |
16350107
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Inorganic industrial materials
|
|---|
| Research Institution | Tokyo University of Agriculture and Technology |
|---|
Principal Investigator |
NAKATO Teruyuki Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor, 大学院共生科学技術研究院, 助教授 (10237315)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Project Status |
Completed (Fiscal Year 2006)
|
| Budget Amount *help |
¥15,200,000 (Direct Cost: ¥15,200,000)
Fiscal Year 2006: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2005: ¥8,800,000 (Direct Cost: ¥8,800,000)
Fiscal Year 2004: ¥3,800,000 (Direct Cost: ¥3,800,000)
|
|---|
| Keywords | niobate / clay / exfoliation / nanosheet / dispersed system / microdomain structure / photoinduced electron transfer / charge separation / ミクロ相分離 / チタン酸塩 / 液晶 / メチルビオロゲン |
|---|
| Research Abstract |
We investigated photochemical behavior of a colloidal system composed of niobate nanosheets prepared by exfoliating layered hexaniobate K_4Nb_6O_<17> known as a photocatalyst, photochemically inactive nanosheets of hectroite clay, and methylviologen (MV^<2+>) that can work as an electron acceptor. The multi-component colloid exhibited stable photoinduced charge-separation. This behavior was ascribed to a unique superstructure of the colloidally dispersed photocatalytically active niobate nanosheets. Such a structural principle can be utilized to design novel photoenergy conversion systems. The results are summarized as follows.
1. Coexistence of the niobate and clay nanosheets is prerequisite for the stable charge-separation. They cause microphase separation to form microdomains in the colloid, and the MV2+ molecules are selectively adsorbed on the clay nanosheets. This structure results in spatial separation of the niobate nanosheets working as an electron donor and MV^<2+> molecules b
… More
ehaving as an electron acceptor to stabilize the charge-separated state.
2. Photoirradiation of the colloid induced electron transfer from the niobate nanosheets to the MV^<2+> molecules. The lifetime of reduced viologen species exceeds 10 h under appropriate conditions, the lifetime which is longer than that observed for the solid system where MV^<2+> molecules are incorporated into the niobate. Such stability is unusual because fluidity of the colloidal system allows backward electron transfer.
3. The stability of charge-separation greatly depends on the concentration of clay coexisting in the colloid. The charge-separated state becomes stable as increasing the clay content. However, electron transfer does not occur when the clay content is very high to gel the colloid. These results suggest that the stable charge-separation takes place when the diffusion of the nanosheets is decelerated but not completely suppressed.
4. The stable charge-separation is achieved by simultaneously utilizing various characteristics of the system, such as domain structure, fluidity, and dividing the donor and acceptor functions by constituents. Less
|
