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Recent Achievements of Fukui Lab. Surf/Interface Chem Group in Osaka Univ.

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Toyonaka-shi, Osaka
Recent Achievements of Fukui Lab. Surf/Interface Chem Group in Osaka Univ.

Research Achievements of Fukui lab (Surface and Interface Chemistry Group) @ Osaka Univ.

09/04/2026

May 6, 2025
J. Am. Ceram. Soc. 108, e20614 (10 pages) (2025) (Open access).

“Surface characterization of sodium silicate glasses after initial water interaction” By K. Miyatani, S. Amma, L. Deng, J. Kalahe, M. Morioka, M. Suehara, M. Ono, S. Urata, J. Du, K. Fukui

The corrosion behavior of sodium silicate glass in water may be understood by clarifying the fundamental processes of interface reactions. We investigated the reaction mechanism of the glass surfaces in contact with water for just an immediate dipping up to 1 h later, using x-ray photoelectron spectroscopy. Silanol formation due to ion exchange of sodium with hydrogen from water was observed from 0 to 30 s, similar to previously reported molecular dynamics simulations. However, the amount of silanol groups decreased after the formation reaction owing to the dehydration of excess silanol groups generated by the initial reactions, thereby promoting the re-formation of siloxane networks at the glass surface. The generated siloxane network was relatively stable for 30 min owing to their rather rigid network. The silanol group concentration increased gradually at the surface after 30 min, owing to a deficiency of dissolved sodium ions. Thereafter, the sodium ions attracted to the negatively charged glass surface gradually left the surface, resulting in an increase of silanol groups when the glass–water reaction proceeded. These observations of the glass–water reaction over a short period provide insight for improving the durability of sodium silicate glass products and developing efficient polishing and cleaning procedures for glass fabrication.

https://ceramics.onlinelibrary.wiley.com/doi/10.1111/jace.20614

18/03/2025

Phys. Chem. Chem. Phys., 2025
DOI:10.1039/D4CP04831H
“Molecular insight into the dynamics at the lithium-containing ionic liquid/gold film electrode interface using electrochemical attenuated total reflection spectroscopies” By T. Kakinoki, A. Imanishi, S. Kondou, I. Tanabe, K. Fukui

The spectral response at the interface between lithium-containing 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI) and a gold electrode was investigated using electrochemical attenuated total reflection spectroscopy (EC-ATR) in the far-ultraviolet and infrared regions. At a negatively charged Au electrode within the cathodic limit, an increase in the EMIM cation signal and a decrease in the TFSI anion signal were observed for neat EMIM-TFSI, indicating the normal replacement of the TFSI anions by the EMIM cations. In contrast, an apparent decrease in the EMIM cation signal and an increase in the TFSI anion signal were observed, suggesting the replacement of the EMIM cation with a Li+ cation coordinated with TFSI anions. The ATR spectral responses were reversible in the electrode potential cycles, likely due to diffusion perpendicular to the electrode or the reorientation of the interfacial ionic liquid components. The surface-stabilized Li+ ions coordinated by the TFSI anions at the negatively charged Au electrode may restrict the direct interaction of the EMIM cation with the electrode, thereby reducing the reduction rate of the EMIM cation, and extending the cathodic limit upon the addition of the Li salt.
https://doi.org/10.1039/D4CP04831H

06/10/2023

May 2, 2023
Langmuir 39, 6846-6854 (2023)
DOI: 10.1021/acs.langmuir.3c00438
“Voltammetric and In Situ Spectroscopic Investigations on the Redox Processes of Trioxotriangulene Neutral Radicals on Graphite Electrodes” By Shohei Kitano, Ichiro Tanabe, Nobutaka Shioya, Takeshi Hasegawa, Tsuyoshi Murata, Yasushi Morita, Ryotaro Tsuji, and Ken-ichi Fukui

To investigate the microscopic electrochemical dynamics of a stable trioxotriangulene (TOT) organic neutral π-radical on a graphite electrode surface, voltammetric and in situ infrared (IR) spectroelectrochemical studies were conducted using electrolyte solutions containing TOT monoanions. Upright columnar crystals (face-on alignment) of the TOT neutral radical were preferentially formed and dissolved in a rather reversible manner in the electrolyte with a low concentration of TOT monoanion under electrochemical conditions; however, more flat-lying columnar crystals (edge-on alignment) were formed in a higher concentration electrolyte. The flat-lying crystals remained on the graphite surface even at a fully reduced potential, owing to the lack of direct π–π interactions between the molecules and the graphite electrode. In situ IR attenuated total reflectance spectroscopy analyses successfully characterized the alignment of the columnar crystals of the TOT neutral radicals and their electrochemical behaviors, including the possible origins of the irreversible redox reaction of TOT on the graphite electrode.
https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00438

17/08/2022

October 15, 2022
Journal of Molecular Liquids, Volume 364, 119998 (2022)
DOI: 10.1016/j.molliq.2022.119998
“Solvation properties of silver ions in ionic liquids using attenuated total reflectance ultraviolet spectroscopy” By M. Imai, I.Tanabe, Y. Ozaki, K. Fukui

The solvation structures of N-butyl-N-methylpyrrolidinium dicyanamide ([BMP][DCA]) surrounding silver ions were investigated using attenuated total reflectance-ultraviolet (ATR-UV) spectroscopy. The addition of Ag+ to [BMP][DCA] red-shifted the [DCA]− absorption band. The shift direction was opposite to that caused by the addition of Li+, and these spectral shifts were qualitatively reproduced using quantum chemical calculations. Multivariate analysis (the multivariate curve resolution-alternating least squares; MCR-ALS) and molecular dynamics simulations were used to decompose the ATR-UV spectra into separate [DCA]− and Ag-solvated [DCA]− spectra. Both multivariate analysis and molecular dynamics simulation showed that the coordination number of [DCA]− around Ag+ was approximately-five. The proposed method using spectroscopic techniques, spectral decomposition, and simulations can be used for the quantitative investigation of various solvation structures, which are fundamental features in electrochemistry.

https://doi.org/10.1016/j.molliq.2022.119998

30/03/2022

March 16, 2022
Langmuir, 38, 12, 3951–3958 (2022)
DOI: 10.1021/acs.langmuir.2c00344
“Interface Behavior of Electrolyte/Quinone Organic Active Material in Battery Operation by Operando Surface-Enhanced Raman Spectroscopy” By Yusuke Morino and Ken-Ichi Fukui

To elucidate the microscopic charge/discharge (delithiation/lithiation) mechanism at the interface of the electrolyte and organic cathode active material in the lithium-ion battery, we prepared a self-assembled monolayer (SAM) electrode of 1,4-benzoquinone terminated dihexyl disulfide (BQ-C6) on Au(111). An electrochemical setup with the BQ-C6 SAM as a working electrode and 1 M lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI)/triethyleneglycol dimethylether (G3) as the electrolyte was used. We adopted the shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) method to obtain sufficient Raman signal of SAM for operando Raman spectroscopy measurements by the enhancement with ∼100 nm diameter Au particles coated with SiO2 shell (average thickness = 2 nm). By this method, we succeeded in acquiring the Raman signal of the molecular monolayer on the model electrode simulating the interface between the electrolyte and the organic active material. In the cyclic voltammogram, two peaks were observed during the reduction reaction (lithiation), whereas only one peak was detected in the course of the oxidation process (delithiation). Simultaneous operando SHINERS showed a two-step spectral shape change in lithiation and coinciding (or simultaneous) one-step recovery during delithiation to match cyclic voltammetry behavior. The results indicate an asymmetric lithiation/delithiation mechanism.

https://doi.org/10.1021/acs.langmuir.2c00344

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Toyonaka-shi, Osaka