Preferential Formation of Layered Structure of Ionic Liquid at Ionic Liquid Aqueous Solution / Graphite Electrode Interfaces Observed by Frequency-Modulation Atomic Force Microscopy

• Harada Tomohiro

  Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Japan

• Yokota Yasuyuki

  Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Japan

• Imanishi Akihito

  Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Japan

• Fukui Ken-ichi

  Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Japan

抄録

Local structure of ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF₄), at IL + water mixtures / highly-oriented pyrolytic graphite (HOPG) interfaces has been investigated using frequency-modulation atomic force microscopy (FM-AFM). The imaging study of surface topography and energy dissipation of IL + water / HOPG interfaces suggested that even the hydrophilic IL molecules favored the HOPG substrate forming stable layers of ILs whose layer thickness corresponded to the averaged ion-pair size. A threshold molar ratio (χ_IL) for the first IL layer formation was between 0.01 and 0.05 and the HOPG surface was completely covered by IL layer at as low as χ_IL = 0.1. Force curve measurements in various concentrations of IL + water mixtures also suggested that the liquid side nature such as the apparent viscosity near the interfaces changed around the critical concentration. Dissolution of the IL layer was found to be a slow process, suggesting that the interface structure was history-dependent. Furthermore, electrochemical potential of the HOPG substrate affected the IL layer formation. Particularly application of positive potential resulted in growth of IL layer at the interface. [DOI: 10.1380/ejssnt.2014.89]

収録刊行物

• e-Journal of Surface Science and Nanotechnology

  e-Journal of Surface Science and Nanotechnology 12 (0), 89-96, 2014

  公益社団法人 日本表面真空学会

キーワード

• Atomic force microscopy
• Electrochemical methods
• Energy dissipation
• Graphite
• Solid-liquid interfaces
• Ionic liquids

詳細情報

• CRID: 1390282680163705984
• NII論文ID: 130004933803
• DOI: 10.1380/ejssnt.2014.89
• ISSN: 13480391
• Web Site: https://www.jstage.jst.go.jp/article/ejssnt/12/0/12_89/_pdf
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可