Bunsho Ohtani
Hokkaido University, Sapporo, Japan
Title: Design, Preparation and Characterization of Functional Nanomaterials Based on Energy-resolved Distribution of Electron Traps
Biography
Biography: Bunsho Ohtani
Abstract
How can we design functional solid materials, such as catalysts and photocatalysts? What is the decisive structural parameters controlling their activities, performance or properties? What isobtained as structural properties by popular conventional analytical methods, such as X-raydiffraction (XRD) or nitrogen-adsorption measurement, is limited to bulk crystalline structure andspecific surface area, i.e., no structural characterization on amorphous phases, if present, andsurface structure has been made so far. This is because there have been no macroscopic analyticalmethods to give surface structural information including possibly-present amorphous phases.
Recently, we have developed reversed double-beam photoacoustic spectroscopy (RDB-PAS) whichenables measure energy-resolved distribution of electron traps (ERDT) for semiconductingmaterials such as metal oxides [1,2]. Those detected electron traps (ETs) seem to be predominantlylocated on the surface for almost all the metal oxide particles, and therefore they reflectmacroscopic surface structure, including amorphous phases, in ERDT patterns. Using an ERDTpattern with the data of CB bottom position (CBB), i.e., ERDT/CBB pattern, it has been shown thatmetal oxide powders, and the other semiconducting materials such as carbon nitride, can beidentified without using the other analytical data such as XRD patterns or specific surface area, andsimilarity/differentness of a pair of metal-oxide samples is quantitatively evaluated as degree ofcoincidence of ERDT/CBB patterns. An approach of material design based on the ERDT/CBBanalyses is introduced [3].[1] Chem. Commun. 2016, 52, 12096-12099. [2] Electrochim. Acta 2018, 264, 83-90. [3]Catal.Today 2019, 321-322, 2-8.