Polarization charge: Theory and applications to aqueous interfaces

Shi, Bobo; Agnihotri, Mithila V.; Chen, Sihan; Black, Richie; Singer, Sherwin J.

doi:10.1063/1.4945760

Cited by 19 publications

(31 citation statements)

References 94 publications

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“…The trough value of the major peak in polarization density at this surface changes from negative number to positive number, suggesting an intense switch (or realignment) in the dipole orientation affected by the stronger E‐field. We notice that the M z ( z ) profile under the 6 V voltage difference has a similar shape as the polarization density profile of the water slab under uniform external field with a strength of 1 V/nm reported by Shi et a l., but only in a qualitative way, the surface polarization behavior, e.g ., the peak value, does not match well. Of course, to make quantitative comparison between the uniform external field simulation method and the constant potential simulation method, one has to use exactly the same system dimensions and make sure the E‐field between the electrode and the water surface (in the CPM simulation) equals the E‐field strength in the applied uniform E‐field simulation.…”

Section: Resultsmentioning

confidence: 99%

“…A few molecular simulation studies on the simple dipolar liquid‐vapor interface properties exposed to a spatially uniform external field have been carried out recently . It is reasonable to employ uniform electric fields in the studies of the structural and thermodynamic behaviors of bulk water or ices with the periodic boundary conditions applied in the simulation .…”

Section: Background and Originality Contentmentioning

confidence: 99%

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A Constant Potential Molecular Dynamics Simulation Study of the Atomic‐Scale Structure of Water Surfaces Near Electrodes

Yang

Wang²,

Liang

et al. 2019

Chin. J. Chem.

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Summary of main observation and conclusion Novel and technologically important processes and phenomena arise at water surfaces in the presence of electric fields. However, experimental measurements on water surfaces are challenging, and the results are scarce and inconclusive. In this work, the constant potential molecular dynamics method, in which the electrode charges are allowed to fluctuate to keep the electric potential fixed, was implemented in the study of a near‐electrode water surface systems. This simulation system was set up with a vapor/liquid‐water/vapor slab and two electrodes under different sets of applied electrostatic potential, yielding i) a detailed characterization of the external E‐field dependent electrostatic potential/density/dipole moment density profiles, and ii) the relationship between the water surface width and the applied electrode voltage differences which has been rarely reported. The adjustments in the number density profiles in the vicinity of water surfaces due to external E‐fields were observed, while the capillary interfacial widths for the surfaces near both cathode and anode were found with different increment rates under increasing E‐fields. By examining dipole density profiles across the water surfaces, we found that external E‐field induced polarization occurs in both bulk and surface regimes, yet the surface polarization densities vary asymmetrically with respect to the increasing E‐fields. Detailed discussions were carried out to explain the correlation between water surface tension and surface widths, as well as the interplay between the surface polarization densities and the hydrogen bond network structure. We conclude that the mechanical and structural properties of the water surfaces could be tuned by both magnitude and direction of the strong external E‐fields. We also recognize that more surface properties with application value, such as dielectric permittivity tensor or surface potential, could also be regulated by the external E‐fields.

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Section: Resultsmentioning

confidence: 99%

Section: Background and Originality Contentmentioning

confidence: 99%

A Constant Potential Molecular Dynamics Simulation Study of the Atomic‐Scale Structure of Water Surfaces Near Electrodes

Yang

Wang²,

Liang

et al. 2019

Chin. J. Chem.

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“…Whether this material property can be applied to interfaces of molecular or mesoscopic dimensions has long been a subject of contention. [2][3][4][5][6][7][8] It has long been suggested that an effective dielectric constant of a microscopic interface has to be introduced, and most researchers have agreed that this effective dielectric constant has to be reduced from the bulk value. [9][10][11][12][13][14][15][16][17][18][19] The extent of reduction has mostly remained unknown.…”

Section: Introductionmentioning

confidence: 99%

Effective Dielectric Constant of Water at the Interface with Charged C₆₀ Fullerenes

et al. 2019

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AZ 85287-1504 a) Dipolar susceptibility of interfacial water and the corresponding interface dielectric constant were calculated from numerical molecular dynamics simulations for neutral and charged states of buckminsterfullerene C 60 . Dielectric constants in the range 10-22, depending on temperature and solute charge, were found. The hydration water undergoes a structural crossover as a function of the solute charge. Its main signatures include the release of dangling O-H bonds pointing toward the solute and the change in the preferential orientations of hydration water from those characterizing hydrophobic to charged substrates. The interface dielectric constant marks the structural transition with a spike. The computational formalism adopted here provides direct access to interface susceptibility from configurations produced by computer simulations. The required property is the cross-correlation between the radial projection of the dipole moment of the solvation shell and the electrostatic potential of the solvent inside the solute.

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“…The DC contribution of the electrical potential difference of each SE before and after (cleaning) the electrochemical cleaning ( Figure 6) showed differences that can be associated with the IP phenomenon. The excitation current produced a progressive reorganization of the electrical charges at the interface until reaching a steady-state potential value in the range of seconds (Shi, et al, 2016). It is worth noting that the potential values closed when they were clean.…”

Section: Electrical Potential Of the Gold Electrode With Respect Tmentioning

confidence: 99%

Limpieza de electrodos y reproducibilidad de medidas de impedancia eléctrica en células HeLa en solución acuosa

Pinto

Pinzón

Meléndez

et al. 2020

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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La espectroscopia de impedancia eléctrica (EIS) se emplea en el estudio de las propiedades eléctricas de células en suspensión. Para medir las propiedades eléctricas de materiales se utilizan dos (sistema de electrodo bipolar), tres (tripolares) y cuatro (tetrapolares) electrodos, siendo las medidas tetrapolares la mejor opción para minimizar los efectos de polarización de electrodo. Cuando se repiten las medidas de EIS en una misma muestra, se espera obtener espectros similares, sin embargo, en algunas situaciones se encuentran diferencias significativas asociadas con la baja reproducibilidad y repetibilidad. Aquí se utilizaron células HeLa dispersas en solución acuosa para evaluar también el efecto de la limpieza en el funcionamiento de los electrodos de oro. La limpieza de las superficies de los electrodos de oro se hizo por voltamperometría cíclica. Se encontró que la reproducibilidad y la repetibilidad de las medidas de impedancia aumentaba al limpiar los electrodos. Estos resultados evidenciaron que la limpieza de la superficie de los electrodos minimizó las contribuciones de la polarización de los electrodos en las mediciones. Además, se propone un modelo de circuito para describir el efecto de las superficies sin limpiar en las medidas eléctricas. Dicho modelo confirma que el efecto observado no se debió a una impedancia de polarización convencional. Más bien se trató de una polarización activa (como un potencial), la cual se presenta a bajas frecuencias y es independiente de la frecuencia de la señal de excitación.

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Polarization charge: Theory and applications to aqueous interfaces

Cited by 19 publications

References 94 publications

A Constant Potential Molecular Dynamics Simulation Study of the Atomic‐Scale Structure of Water Surfaces Near Electrodes

A Constant Potential Molecular Dynamics Simulation Study of the Atomic‐Scale Structure of Water Surfaces Near Electrodes

Effective Dielectric Constant of Water at the Interface with Charged C₆₀ Fullerenes

Limpieza de electrodos y reproducibilidad de medidas de impedancia eléctrica en células HeLa en solución acuosa

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Polarization charge: Theory and applications to aqueous interfaces

Cited by 19 publications

References 94 publications

A Constant Potential Molecular Dynamics Simulation Study of the Atomic‐Scale Structure of Water Surfaces Near Electrodes

A Constant Potential Molecular Dynamics Simulation Study of the Atomic‐Scale Structure of Water Surfaces Near Electrodes

Effective Dielectric Constant of Water at the Interface with Charged C60 Fullerenes

Limpieza de electrodos y reproducibilidad de medidas de impedancia eléctrica en células HeLa en solución acuosa

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Effective Dielectric Constant of Water at the Interface with Charged C₆₀ Fullerenes