Kyoto University · Materials Science
Professor Hiroyuki Asakura's research lab specializes in advanced X-ray absorption spectroscopy (XAS) techniques, particularly operando XANES and EXAFS, to investigate the electronic and local structural properties of transition metal catalysts and rare earth compounds under realistic reaction conditions. The lab focuses on understanding dynamic surface and electronic behaviors during catalytic reactions, such as those in three-way catalysts, with an emphasis on oxidation states, d-orbital splitting, and metal-support interactions. Their work combines experimental XAS with theoretical calculations to elucidate the relationship between local atomic structure and catalytic performance.
Figures are computed from collected data and may differ slightly.
The dynamic behavior of Rh species in 1 wt% Rh/Al<sub>2</sub>O<sub>3</sub> catalyst during the three-way catalytic reaction was examined using a micro gas chromatograph, a NO<sub>x</sub> meter, a quadrupole mass spectrometer, and time-resolved quick X-ray absorption spectroscopy (XAS) measurements at a public beamline for XAS, BL01B1 at SPring-8, operando. The combined data suggest different surface rearrangement behavior, random reduction processes, and autocatalytic oxidation processes of Rh s
La L1 and L3-edge X-ray absorption near-edge structure (XANES) of various La oxides were classified according to the local configuration of La. We found a correlation between both of the areas of the pre-edge peaks of the La L1-edge XANES spectra and the full width at half-maximum of white line of La L3-edge XANES spectra and the local configuration of La. Theoretical calculation of the XANES spectra and local density of states reveals the difference of La L1 and L3-edge XANES spectra of various
The characteristics of K-, L1-, and L3-edges of XANES (X-ray Absorption Near Edge Structure) spectra of group V, VI, and VII compounds, which have different coordination number, number of d electrons, and the coordination sphere symmetry, have been classified. Two p → d transitions were observed in the second derivative plots of the L3-edge XANES spectra for the group V, VI, and VII compounds. These two transitions can be assigned to split d orbitals. The splitting and area of the two white line
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