Imaging of the Liquid−Liquid Interface under Electrochemical Instability Using Confocal Fluorescence Microscopy

Kitazumi, Yuki; Kakiuchi, Takashi

doi:10.1021/la901374f

Cited by 16 publications

(22 citation statements)

References 18 publications

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“…Changing the surface coverage with an electric eld could cause the Marangoni instabilities that lead to the spontaneous oscillation of the interfacial surface tension. [46][47][48] Recently, Kovalchuk has reviewed this topic with the absence of the electric eld.…”

Section: Marangoni-type Shutter Based On Gold Nanoparticle Assembliesmentioning

confidence: 99%

Electrovariable gold nanoparticle films at liquid–liquid interfaces: from redox electrocatalysis to Marangoni-shutters

et al. 2017

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Control over the physical properties of nanoparticle assemblies at a liquid-liquid interface is a key technological advancement to realize the dream of smart electrovariable nanosystems.Electrified interfaces, such as the interface between two immiscible electrolytes solutions (ITIES), are almost an ideal platform for realizing this dream. Here, we show that the Galvani potential difference across soft interfaces can be effectively used to manipulate: (i) the reactivity of gold nanoparticle assemblies through varying the Fermi level (both chemically and electrochemically); (ii) the location distribution of the nanoparticles at the liquid-liquid interface. In the first case, in addition to our previous studies on electron transfer reactions (ET) across the ITIES, we used intensity modulated photocurrent spectroscopy (IMPS) to study the kinetics of photo-induced electrochemical reactions at the ITIES. As expected, the direct adsorption of gold nanoparticles at the interface modifies the kinetics of the ET reaction (socalled, interfacial redox electrocatalysis), however it did not lead to an increased photocurrent by "plasmonic enhancement". Rather, we found that the product separation depends on double layer effects while the product recombination is controlled by the Galvani potential difference between the two phases. In the second case, we demonstrated that polarizing the ITIES caused migration of gold nanoparticles from the middle region of the cell to its periphery. We called such systems "Marangoni-type shutters". This type of electrovariable plasmonic system did not experience diffusion limitation in terms of the adsorption/ desorption of nanoparticles and the entire movement of nanoparticle assemblies happened almost instantly (within a second). It opens a fresh view on electrovariable plasmonics and presents new opportunities to create smart nanosystems at the ITIES driven with an electric field.

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Section: Marangoni-type Shutter Based On Gold Nanoparticle Assembliesmentioning

confidence: 99%

Electrovariable gold nanoparticle films at liquid–liquid interfaces: from redox electrocatalysis to Marangoni-shutters

et al. 2017

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“…34,37,40,7988 A model based on the kinetics of ion-transfer, adsorption, and desorption reactions at the interface was proposed to explain the irregular current in a certain potential region on iontransfer voltammograms. 89 However, this model disagrees with the irregular current on the potential-step chronoamperogram for the transfer of surface-active ions, 82,83,86,88 since the model assumes the steady-state current when the potential is kept constant.…”

Section: A Historical Perspectivementioning

confidence: 94%

“…. 88 The broken line in Figure 5a is a voltammogram recorded in the presence of sorbitan monooleate. Figure 5b shows the CFM images of the interface simultaneously recorded with the voltammogram shown in the solid line in Figure 5a.…”

Section: Imaging the Evolution Of Instabilitymentioning

confidence: 99%

“…In other words, the large stable region and the locally unstable domains coexist in a globally metastable state. 88 …”

Section: Imaging the Evolution Of Instabilitymentioning

confidence: 99%

“…The first question is the origin of the oscillation of Á W O º which has a period of 250 s. A model taking into account the formation and destruction of the surfactant layer at the interface 33,35,38 disagrees with this slow oscillation because the concentration of TBADS is high enough to restore the concentration profile in the vicinity of the interface in such a long period of time. The second question is why locally unstable submillimeter-scale domains at the interface at the incipient stage of the electrochemical instability 88 collaborate to create a rhythm that concerts with each other over the entire interface spontaneously. The third question is why the induction period of a few minute is required.…”

Section: Oscillation Phenomenamentioning

confidence: 99%

See 2 more Smart Citations

Electrochemical Instability in Liquid–Liquid Two-Phase Systems

Kitazumi¹,

Kakiuchi²

2011

Bulletin of the Chemical Society of Japan

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On the basis of the dependency of adsorption and partitioning of ionic surfactant on the phase-boundary potential (Á W O º), it is possible to understand in a unified manner various instability phenomena at the liquid«liquid interface in the presence of ionic surfactants, such as spontaneous emulsification, oscillation of Á W O º and interfacial tension, and irregularly increased currents on voltammograms of the transfer of surface-active ions across the interface. These instabilities are associated with the electrochemical instability, which defines a thermodynamically unstable condition at the liquid«liquid interface in terms of Á W O º and is a fundamental concept to understand the instabilities in the presence of ionic surfactants. The characteristic manifestations of the electrochemical instability, that is, the irregularly increased current on voltammograms in the transfer of surface-active ions, the spontaneous emulsification, and the spontaneous oscillation of Á W O º can be designed based on the criterion of the electrochemical instability.

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Voltammetric Manifestation of the Ultraslow Dynamics at the Interface between Water and an Ionic Liquid

Kakiuchi¹,

Yasui²,

Kitazumi³

et al. 2010

ChemPhysChem

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The ultraslow relaxation (on the order of minutes) of the electrical double-layer structure, related to a change in the phase-boundary potential across the interface between water (W) and the ionic liquid (IL) trioctylmethylammonium bis(nonafluorobutanesufonyl)amide ([TOMA(+)][C(4)C(4)N(-)]) (Y. Yasui et al., J. Phys. Chem. B. 2009, 113, 3273), appears to be invisible in the transfer of tetrapropylammonium ions across the [TOMA(+)][C(4)C(4)N(-)]|W interface, provided that the charging current, which shows an unusual dependence on the voltage scan rate, is subtracted to obtain the faradaic current. This counterintuitive observation can be explained by the differences in the timescales of the fast and slow components of the relaxation dynamics of the electrical double layer on the IL side (ms and min). In contrast, the effect of the slow dynamics becomes surfaced in ion-transfer voltammetry when the ion is surface-active. The transfer of pentadecafluorooctanoate across the [TOMA(+)][C(4)C(4)N(-)]|W interface is irreversible, which is attributable to the self-inhibition of pentadecafluorooctanoate ions transferred to the IL phase. This process is likely to be affected by the ultraslow structural change of the IL side of the interface.

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Imaging of the Liquid−Liquid Interface under Electrochemical Instability Using Confocal Fluorescence Microscopy

Cited by 16 publications

References 18 publications

Electrovariable gold nanoparticle films at liquid–liquid interfaces: from redox electrocatalysis to Marangoni-shutters

Electrovariable gold nanoparticle films at liquid–liquid interfaces: from redox electrocatalysis to Marangoni-shutters

Electrochemical Instability in Liquid–Liquid Two-Phase Systems

Voltammetric Manifestation of the Ultraslow Dynamics at the Interface between Water and an Ionic Liquid

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