Kyushu University Academic Staff Educational and Research Activities Database
List of Reports
Haruno Murayama Last modified date:2020.06.17

Associate Professor / Department of Chemistry / Faculty of Sciences


Reports
1. Silica-supported Au nanoparticles (NPs) (Au/SiO2) were applied as a selective adsorbent for 1,3-dimethyltrisulfane (DMTS), which is the major component of the aged odor in Japanese sake. Au/SiO2 removed DMTS in model solution and Japanese sake without reducing ethyl hexanoate (EH) concertation, which is responsible for the fruity aroma, while activated carbon reduced both DMTS and EH. The sensory evaluation of Japanese sake demonstrated that the aged odor and the sulfur smell became weaker by Au/SiO2 adsorbent without significant changes in other sensory properties. Adsorbed DMTS formed monolayer on the Au NPs surface and the adsorption was according to the Langmuir model. Because the adsorbed amount of DMTS depended on the exposed number of Au atoms, chloride-free and water-soluble Au complex coordinated with β-alanine (Au–β-ala) was synthesized to prepare small Au NPs supported on silica. The structure of Au–β-ala analyzed by XAFS and TG-DTA was the square-planar coordination and mononuclear complex of Au3+. The thermal behavior of Au–β-ala, which is lower decomposition and reduction temperature prevented Au atoms from aggregation and then Au NPs less than 3 nm were supported on silica..
2. Visualization of Electrochemical Reactions in Operating Electrode of Li-ion Battery
Haruno Murayama, Koji Kitada, Katsutoshi Fukuda
Spatial variations of Li-ion concentration in cross section of composite electrodes in Li-ion batteries (LIBs) owing to their complex structures were investigated under operation condition. To visualize spatially-inharmonious electrochemical reactions occurring in the sheet-like composite electrodes with a thickness of 100 μm, we developed spatial and time-resolved spectroscopic X-ray diffraction (XRD) analysis that uses continuous irradiation with monochromatic X-rays using a confocal setup as a direct observation technique. Their position sensitivity, spatial-resolution, and profile resolution were carefully evaluated from a pre-measurement using references and model electrode. Then, this method was applied to operand analyses for the practical LIB cells composed of LiNi1/3Co1/3Mn1/3O2 known as one of the most common active materials for the positive electrode of LIBs. The spatial variations of Li-ions in the cross section of composite electrodes were successfully determined with a depth resolution of 30 μm during cell operation. On the basis of the results from the newly developed analysis, we discussed effect of the electrolyte concentration (LiPF6) on Li-ion transportation from the counter electrode side to the current collector side during the operation. .