Bunsho Ohtani

Institute for Catalysis, Hokkaido University, Japan

Title: Design, Preparation and Characterization of Photofunctional Materials Based on Energy-resolved Distribution of Electron Traps

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Biography

The research work on photocatalysis by Professor Bunsho Ohtani started in 1981 when he was a Ph. D. course student in Kyoto University.  Since then he has been studying photocatalysis and related topics for 40 years and published more than 300 original papers (h-index: 70) and two single-author books.  After gaining his Ph. D. degree from Kyoto University in 1985, he became an assistant professor in the university.  In 1996, he was promoted to an associate professor in Graduate School of Science, Hokkaido University and was then awarded a full professor position in the Catalysis Research Center (presently Institute for Catalysis), Hokkaido University in 1998.  He was awarded several times form the societies related to chemistry, photochemistry, electrochemistry and catalysis chemistry.

Abstract

How can we design solid photocatalysts? What is the decisive factor controlling photocatalytic activities? So-called band-structure model (BSM), electrons in a valence band (VB) of a photocatalyst is photoexcited to a conduction band (CB), leaving positive holes in VB, and electrons and holes reduce and oxidize, respectively, substrates adsorbed on the surface of the photocatalyst, does suggest preferable band positions for redox reaction uniquely decided only by crystalline structure. The other possible factors, e.g., particle size and surface structure, cannot be discussed within BSM. Recently, we have developed reversed double-beam photoacoustic spectroscopy (RDB-PAS) which enables measure energy-resolved density of electron traps (ERDT).  Those electron traps (ETs) seem to be predominantly located on the surface of almost all the metal oxide particles, with exception of nickel oxide and therefore they reflect macroscopic surface structure in ERDT patterns. Using ERDT pattern with the data of CB-bottom position (CBB), i.e., ERDT/CBB patterns, it has been shown that metal oxide powders can be identified without using the other analytical data such as X-ray diffraction patterns or specific surface area, and similarity/differentness of a pair of metal-oxide samples can be quantitatively evaluated as degree of coincidence of ERDT/CBB patterns.  In this talk, a novel approach of material design based on the ERDT/CBB patterns is introduced.