2007 Fiscal Year Final Research Report Summary
Design of high functional photocatalysts based on higher space and time analyses of the active reaction species
| Project/Area Number |
14050043
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Nagaoka University of Technology |
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Principal Investigator |
NASAKA Yoshio Nagaoka University of Technology, Departmentof Chemistry, Professor (30134969)
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| Co-Investigator(Kenkyū-buntansha) |
MURAKAMI Yoshinori Nagaoka University of Technology, Research Associate (70293256)
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| Project Period (FY) |
2002 – 2007
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| Keywords | photocatalysis / nano materials / surface interface reaction / titanium dioxide / new energy |
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| Research Abstract |
This project aims to design a new superior active photocatalysts by elucidating the behavior and time dependence of active species on the catalysts. In this final year, singlet molecular oxygen and OH radical were investigated. Singlet oxygen was formed as a absorbed state, and it decays by the interaction with titanium oxide. The reduction of molecular oxygen followed by the oxidation at the same photocatalysts has been regarded as the electron-hole recombination in the photocatalyst. Though the singlet oxygen was deactivated without reaction, we could show the decay of singlet oxygen by some organic molecules is within a micro second. The OH radicals released from titanium oxide to gas phase were detected by means of laser induced fluorescence technique and the mechanism of the formation of OH radical was investigated from the time dependence of the detected radicals. We found that the OH radical was formed by the reduction of adsorbed hydrogen peroxides which are accumulated on the surface by the oxidation of water and the reduction of molecular oxygen. Heat treatment of titanium oxide powders changes the properties of surface OH groups and promotes the OH radical formation. Based on the above observation, a photocatalyst of tube structure, titanate nanotube, was prepared and photocatalytic activities were tested. Since the negatively charged titanate nanotube accommodates negatively charged species, it was demonstrated the potential applications to the decomposition of cationic species. In the future study, the analysis of hydrogen peroxide on the photocatalysts seems to be an important subject.
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