Potential-induced restructuring dynamics of ionic liquids on a gold electrode: Steric effect of constituent ions studied by surface-enhanced infrared absorption spectroscopy

Motobayashi, Kenta; Nishi, Naoya; Inoue, Yuki; Minami, Kazuya; Sakka, Tetsuo; Osawa, Masatoshi

doi:10.1016/j.jelechem.2017.02.049

Cited by 40 publications

(57 citation statements)

References 62 publications

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“…Thus, because the adsorption density was the smallest, the friction coefficient was drastically increased, after which, when the electric voltage of the surface was 0 V, the friction coefficients remained elevated. It was thought that an excess charge must be provided to change the adsorption of the ions owing to the presence of energy barriers [35]. In other words, 0 V was too small a value to change the adsorption of ions.…”

Section: State Of Ionic Liquids Against Electric Potential Of the Surmentioning

confidence: 99%

Friction Control by Applying Electric Potential under Lubrication with Ionic Liquids

et al. 2019

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This study investigated the effects of the electric potential of a surface on the lubricating capabilities of ionic liquids. The friction coefficient of 1-butyl-3-methylimidazolium iodide was unchanged by the electric potential of the surface because this ionic liquid has difficulty moving in a solution owing to its low conductivity. However, the friction coefficient, when lubricated with 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate and 1-butyl-3-methylimidazolium hexafluorophosphate, changed when the electric potential of the surface was varied. At-2.0 V, cations were adsorbed on the sliding surface. The alkyl chain of cations supported the load and achieved a low friction coefficient. However, at 2.0 V, anions were adsorbed on the sliding surface. Such ions cannot support the load, and thus reach a high friction coefficient.

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Section: State Of Ionic Liquids Against Electric Potential Of the Surmentioning

confidence: 99%

Friction Control by Applying Electric Potential under Lubrication with Ionic Liquids

et al. 2019

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“…[12][13][14][15][16][17] Electrochemical impedance spectroscopy (EIS) is the most popular experimental method for evaluating the differential capacitance at the IL/electrode interface. [18][19][20] In numerous studies, the slow dynamics of the EDL structure of ILs, such as ultraslow relaxation 19,[21][22][23][24][25] and hysteresis, 18,[26][27][28][29][30] have been revealed. The typical ac potential oscillation in EIS measurements is faster than the slow EDL dynamics, making EIS unsuitable to evaluate the static capacitance for comparison with theoretical predictions.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical surface plasmon resonance measurements of camel-shaped static capacitance and slow dynamics of electric double layer structure at the ionic liquid/electrode interface

Zhang

Nishi

Sakka

2020

The Journal of Chemical Physics

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Electrochemical surface plasmon resonance (ESPR) is applied to evaluate the relative static differential capacitance at the interface between 1butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ionic liquid (IL) and a gold electrode, based on the relationship between the SPR angle and surface charge density on the electrode. Potential-step and potential-scan ESPR measurements are used to probe the dynamics of the electric double layer (EDL) structure that exhibit anomalously slow and asymmetrical characteristics depending on the direction of potential perturbation. EDL dynamics respond at least 30 times more slowly to changes of potential in the positive direction than in the negative direction. ESPR experiments with the positive-going potential scan are significantly affected by the slow dynamics even at a slow scan. The surface charge density that reflects the relative static capacitance is obtained from the negative-going potential scans. The evaluated quasi-static differential capacitance exhibits a camel-shaped potential dependence, thereby agreeing with the prediction of the mean-field lattice gas model of the EDL in ILs. ESPR is shown to be an effective experimental method for determining relative values of the static differential capacitance.

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“…Despite being a salt, ionic liquids exist in the liquid phase at a temperature of 100 • C or lower [1][2][3]. They are good candidates as new lubricant oils or additives because of their unique characteristics, including their non-volatility, low vapor pressure, the ability to remain in the liquid phase over a wide temperature range, low viscosity, and an infinite number of ion combinations [4][5][6][7][8]. Kondo et al reported the use of ionic liquids as adsorption films for magnetic thin films inspired by the use of ionic liquids in the tribology field [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Lubricating Properties of Cyano-Based Ionic Liquids against Tetrahedral Amorphous Carbon Film

et al. 2020

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Ionic liquids have unique characteristics, which render them ideal candidates as new base oils or additives. In particular, there are great expectations from the combination of diamond-like carbon and cyano-based ionic liquids. Lubricating properties of cyano-based ionic liquids have been studied on specific tetrahedral amorphous carbon (ta-C) films. After lubrication, ta-C film/ta-C film contact interface exhibits exceedingly low friction. Therefore, it is necessary to understand this low friction phenomenon. The current study evaluated the lubricating mechanism of cyano-based ionic liquids against ta-C films. 1-Butyl-3-methylimidazolium dicyanamide ((BMIM)(DCN)) and 1-butyl-3-methylimidazolium tricyanomethane ((BMIM)(TCC)) were used as lubricants, with the latter exhibiting low friction coefficient of 0.03. Steel cylinders and disks with ta-C films were used as test specimens. Raman spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and thermogravimetric analysis (TGA) helped us understand the mechanism of low friction induced by (BMIM)(TCC). Graphitization of the ta-C film at high temperatures might have caused the reduction in friction between the films. Similarly, anion adsorption on the worn surface at high temperatures also led to reduced friction. However, the TGA result showed a different trend than that of the sliding test. Our results indicate that the cyano-based ionic liquids underwent tribo-decomposition at low temperatures. Further, a minimum temperature was required for the adsorption of anions onto the sliding surface.

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Potential-induced restructuring dynamics of ionic liquids on a gold electrode: Steric effect of constituent ions studied by surface-enhanced infrared absorption spectroscopy

Cited by 40 publications

References 62 publications

Friction Control by Applying Electric Potential under Lubrication with Ionic Liquids

Friction Control by Applying Electric Potential under Lubrication with Ionic Liquids

Electrochemical surface plasmon resonance measurements of camel-shaped static capacitance and slow dynamics of electric double layer structure at the ionic liquid/electrode interface

Lubricating Properties of Cyano-Based Ionic Liquids against Tetrahedral Amorphous Carbon Film

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