Title：Nanoscale Visualization of TiO2Photocatalytic Reactions
Time：April 27, 2016（Wednesday） 13:30
Venue：Lecture Hall of SESE
To develop efficient TiO2 photocatalytic reactions, it is important to reveal and understand the molecular interactions and the mechanism of chemical reactions at heterogeneous interfaces of TiO2 photocatalysts. We have been investigating TiO2 photocatalytic reactions using single-molecule fluorescence imaging techniques and gain information related to spatial and temporal heterogeneities of TiO2 photocatalysts in the reactions, which are always masked by ensemble averaging.
Single-molecule fluorescence microscopy has been used to visualize TiO2 photocatalytic reactions at the heterogeneous interface in the nanometer scale. We synthesized novel fluorogenic probes to selectively observe the catalytic reactions. Such probes are designed to become fluorescent upon the reaction with target species under the photoirradiation. The position of individual fluorescent products can be determined with several tens nanometers spatial resolution by two-dimensional Gaussian fitting. In addition, the quantitative analysis of fluorescence intensity trajectory or fluctuation can reveal the underlying properties of individual catalysts.
We prepared nanometer- and micrometer-sized crystals of TiO2 photocatalysts, and explore the photocatalytic reactions on individual catalysts by single-molecule fluorescence microscopy with newly developed redox-responsive fluorogenic probes. From the analysis of spatial distribution of reactive sites, the relationship between surface structures and chemical reactivity were elucidated. From the quantitative analysis of on/off duration times, we also determined the turnover frequency of individual catalysts, adsorption and dissociation rates, interfacial electron transfer rates, and temporal fluctuation of reaction efficiency.
The proper understanding of structures and reactions at heterogeneous interfaces can develop the general concept of chemistry and help advance the emerging applications of nanocatalysts for environmentally and economically sustainable uses.
Introduction of the Lecturer:
B.S. Osaka University, Chemistry 1971~1975.
M.S. Osaka University, Chemistry 1975~1977.
Ph.D. Osaka University, Chemistry 1977~1980.
Ph.D. degree: Osaka University, supervised with Prof. H. Sakurai, "Interactions and reactions of three-components involving photoelectron transfer mechanism" 1980.
1980~1982, Research Associate, Department of Chemistry, University of Texas at Dallas, supervisor: Prof. R. A. Caldwell.
1982~1983, Guest Researcher, The Institute of Physical and Chemical Research (RIKEN).
1983~1992, Researcher, The Institute of Physical and Chemical Research.
1992~1994, Senior Researcher, The Institute of Physical and Chemical Research.
1994~1997, Assoc. Prof., Dept. of Molecular Excitation Chemistry, Division of Organic Molecular Science, The Institute of Scientific and Industrial Research (SANKEN), Osaka University.
1997~present, Prof., Dept. of Molecular Excitation Chemistry, Division of Organic Molecular Science, The Institute of Scientific and Industrial Research (SANKEN), Osaka University.
1999~2004, Director of Molecular Analysis Center, The Institute of Scientific and Industrial Research, Osaka
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