Transistor based study of the electrolyte/SiO<sub>2</sub> interface

Gentil, Cédric; Côte, Denis; Bockelmann, Ulrich

doi:10.1002/pssa.200622447

Cited by 12 publications

(14 citation statements)

References 22 publications

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“…For example, specific adoption of ions could be added to the boundary conditions, providing an additional mechanism for charge regulation of the surface [29,117,118], in addition to Faradaic polarization, coupled through the FBV equations. The PNP ion transport equations could be extended to include recombination bulk reactions (ion-ion, ion-defect, etc.)…”

Section: Discussionmentioning

confidence: 99%

Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes

Yan

Bazant

Biesheuvel³

et al. 2017

Phys. Rev. E

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Linear sweep and cyclic voltammetry techniques are important tools for electrochemists and have a variety of applications in engineering. Voltammetry has classically been treated with the Randles-Sevcik equation, which assumes an electroneutral supported electrolyte. In this paper, we provide a comprehensive mathematical theory of voltammetry in electrochemical cells with unsupported electrolytes and for other situations where diffuse charge effects play a role, and present analytical and simulated solutions of the time-dependent PoissonNernst-Planck equations with generalized Frumkin-Butler-Volmer boundary conditions for a 1:1 electrolyte and a simple reaction. Using these solutions, we construct theoretical and simulated current-voltage curves for liquid and solid thin films, membranes with fixed background charge, and cells with blocking electrodes. The full range of dimensionless parameters is considered, including the dimensionless Debye screening length (scaled to the electrode separation), Damkohler number (ratio of characteristic diffusion and reaction times), and dimensionless sweep rate (scaled to the thermal voltage per diffusion time). The analysis focuses on the coupling of Faradaic reactions and diffuse charge dynamics, although capacitive charging of the electrical double layers is also studied, for early time transients at reactive electrodes and for nonreactive blocking electrodes. Our work highlights cases where diffuse charge effects are important in the context of voltammetry, and illustrates which regimes can be approximated using simple analytical expressions and which require more careful consideration.

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Section: Discussionmentioning

confidence: 99%

Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes

Yan

Bazant

Biesheuvel³

et al. 2017

Phys. Rev. E

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“…This is consistent with the prediction that SC becomes important only at low salt concentrations, 18 but we must also consider the effect of charge regulation. It is well known that that the surface charge of silica is regulated by the dissociation of silanol groups, 45,58,59 SiOH ←→ SiO − + H + (pK=7.5)…”

Section: Overlimiting Currentmentioning

confidence: 99%

Overlimiting Current and Shock Electrodialysis in Porous Media

et al. 2013

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Most electrochemical processes, such as electrodialysis, are limited by diffusion, but in porous media, surface conduction and electroosmotic flow also contribute to ionic flux. In this article, we report experimental evidence for surface-driven overlimiting current (faster than diffusion) and deionization shocks (propagating salt removal) in a porous medium. The apparatus consists of a silica glass frit (1 mm thick with a 500 nm mean pore size) in an aqueous electrolyte (CuSO4 or AgNO3) passing ionic current from a reservoir to a cation-selective membrane (Nafion). The current-voltage relation of the whole system is consistent with a proposed theory based on the electroosmotic flow mechanism over a broad range of reservoir salt concentrations (0.1 mM to 1.0 M) after accounting for (Cu) electrode polarization and pH-regulated silica charge. Above the limiting current, deionized water (≈10 μM) can be continuously extracted from the frit, which implies the existence of a stable shock propagating against the flow, bordering a depleted region that extends more than 0.5 mm across the outlet. The results suggest the feasibility of shock electrodialysis as a new approach to water desalination and other electrochemical separations.

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“…Taking the silica-water interface for example [85,86], previous treatments take advantage of the experimentally supported "1-pK basic Stern model" [114,115], which describes the various reactions that can occur at the silica-water interface. They are sensitive to the chemical nature of the interface and effective at separations larger than the Debye length.…”

Section: F Comparison and Contrast With The Traditional Picturementioning

confidence: 99%

“…This discrepancy is generally attributed to the "charge regulation" phenomenon, denoting the fact that the interfacial charge layer must vary as a function of local environment. Theoretically, the experimental results can be interpreted by using a parameter that interpolates the surface charge density implied by the CC and CP boundary conditions [83][84][85][86]. However, the physical meaning of the interpolation parameter is not clear.…”

Section: Introductionmentioning

confidence: 99%

Self-Consistent Approach to Global Charge Neutrality in Electrokinetics: A Surface Potential Trap Model

Wan

Liao

et al. 2014

Phys. Rev. X

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In this work, we treat the Poisson-Nernst-Planck (PNP) equations as the basis for a consistent framework of the electrokinetic effects. The static limit of the PNP equations is shown to be the charge-conserving Poisson-Boltzmann (CCPB) equation, with guaranteed charge neutrality within the computational domain. We propose a surface potential trap model that attributes an energy cost to the interfacial charge dissociation. In conjunction with the CCPB, the surface potential trap can cause a surface-specific adsorbed charge layer σ. By defining a chemical potential μ that arises from the charge neutrality constraint, a reformulated CCPB can be reduced to the form of the Poisson-Boltzmann equation, whose prediction of the Debye screening layer profile is in excellent agreement with that of the Poisson-Boltzmann equation when the channel width is much larger than the Debye length. However, important differences emerge when the channel width is small, so the Debye screening layers from the opposite sides of the channel overlap with each other. In particular, the theory automatically yields a variation of σ that is generally known as the "charge regulation" behavior, attendant with predictions of force variation as a function of nanoscale separation between two charged surfaces that are in good agreement with the experiments, with no adjustable or additional parameters. We give a generalized definition of the ζ potential that reflects the strength of the electrokinetic effect; its variations with the concentration of surface-specific and surfacenonspecific salt ions are shown to be in good agreement with the experiments. To delineate the behavior of the electro-osmotic (EO) effect, the coupled PNP and Navier-Stokes equations are solved numerically under an applied electric field tangential to the fluid-solid interface. The EO effect is shown to exhibit an intrinsic time dependence that is noninertial in its origin. Under a step-function applied electric field, a pulse of fluid flow is followed by relaxation to a new ion distribution, owing to the diffusive counter current. We have numerically evaluated the Onsager coefficients associated with the EO effect, L 21 , and its reverse streaming potential effect, L 12 , and show that L 12 ¼ L 21 in accordance with the Onsager relation. We conclude by noting some of the challenges ahead.

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Transistor based study of the electrolyte/SiO₂ interface

Cited by 12 publications

References 22 publications

Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes

Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes

Overlimiting Current and Shock Electrodialysis in Porous Media

Self-Consistent Approach to Global Charge Neutrality in Electrokinetics: A Surface Potential Trap Model

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Transistor based study of the electrolyte/SiO2 interface

Cited by 12 publications

References 22 publications

Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes

Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes

Overlimiting Current and Shock Electrodialysis in Porous Media

Self-Consistent Approach to Global Charge Neutrality in Electrokinetics: A Surface Potential Trap Model

Contact Info

Product

Resources

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Transistor based study of the electrolyte/SiO₂ interface