Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode

A. Eden, K. Scida, N. Arroyo-Currás, J. C.T. Eijkel, C. D. Meinhart, S. Pennathur (Corresponding Author)

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    Abstract

    We present the most comprehensive two-dimensional numerical model to date for a nanoconfined bipolar electrochemical system. By accounting for the compact Stern layer and resolving the diffuse part of the electrical double layer at the bipolar electrode (BPE) surface and channel walls, our model captures the impact of surface polarization and ionic charge-screening effects on the heterogeneous charge-transfer kinetics, as well as nonlinear electrokinetic transport phenomena such as induced-charge electroosmosis and concentration polarization. We employ the Poisson-Nernst-Planck and Stokes flow system of equations, unified with generalized Frumkin-Butler-Volmer reaction kinetics, to describe water electrolysis reactions and the resulting transport of ions and dissolved gases in the confined BPE system. Our results demonstrate that under a sufficiently large applied electric field, the rapid reaction kinetics on our Pt BPE dynamically transition from charge-transfer-limited to mass-transfer-limited temporal regimes as regions depleted of redox species form and propagate outward from the respective BPE poles. This phenomenon was visualized experimentally with a pH-sensitive fluorescein dye and showed excellent phenomenological agreement with our numerical calculations, providing a foundation for further understanding and developing bipolar electrochemical processes in confined geometries. We introduce two prospective applications arising from our work: (1) a hybrid hydrodynamic/electrochemical peristaltic pump and (2) deducing information about chemical kinetics through simulation.

    Original languageEnglish
    Pages (from-to)5353-5364
    Number of pages12
    JournalJournal of physical chemistry C
    Volume123
    Issue number9
    DOIs
    Publication statusPublished - 7 Mar 2019

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    electrokinetics
    Reaction kinetics
    Electrodes
    reaction kinetics
    electrodes
    Charge transfer
    charge transfer
    Polarization
    Electroosmosis
    dissolved gases
    Stokes flow
    polarization
    electrolysis
    Fluorescein
    Electrolysis
    mass transfer
    Numerical models
    Poles
    Screening
    Coloring Agents

    Keywords

    • UT-Hybrid-D

    Cite this

    Eden, A. ; Scida, K. ; Arroyo-Currás, N. ; Eijkel, J. C.T. ; Meinhart, C. D. ; Pennathur, S. / Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode. In: Journal of physical chemistry C. 2019 ; Vol. 123, No. 9. pp. 5353-5364.
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    abstract = "We present the most comprehensive two-dimensional numerical model to date for a nanoconfined bipolar electrochemical system. By accounting for the compact Stern layer and resolving the diffuse part of the electrical double layer at the bipolar electrode (BPE) surface and channel walls, our model captures the impact of surface polarization and ionic charge-screening effects on the heterogeneous charge-transfer kinetics, as well as nonlinear electrokinetic transport phenomena such as induced-charge electroosmosis and concentration polarization. We employ the Poisson-Nernst-Planck and Stokes flow system of equations, unified with generalized Frumkin-Butler-Volmer reaction kinetics, to describe water electrolysis reactions and the resulting transport of ions and dissolved gases in the confined BPE system. Our results demonstrate that under a sufficiently large applied electric field, the rapid reaction kinetics on our Pt BPE dynamically transition from charge-transfer-limited to mass-transfer-limited temporal regimes as regions depleted of redox species form and propagate outward from the respective BPE poles. This phenomenon was visualized experimentally with a pH-sensitive fluorescein dye and showed excellent phenomenological agreement with our numerical calculations, providing a foundation for further understanding and developing bipolar electrochemical processes in confined geometries. We introduce two prospective applications arising from our work: (1) a hybrid hydrodynamic/electrochemical peristaltic pump and (2) deducing information about chemical kinetics through simulation.",
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    Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode. / Eden, A.; Scida, K.; Arroyo-Currás, N.; Eijkel, J. C.T.; Meinhart, C. D.; Pennathur, S. (Corresponding Author).

    In: Journal of physical chemistry C, Vol. 123, No. 9, 07.03.2019, p. 5353-5364.

    Research output: Contribution to journalArticleAcademicpeer-review

    TY - JOUR

    T1 - Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode

    AU - Eden, A.

    AU - Scida, K.

    AU - Arroyo-Currás, N.

    AU - Eijkel, J. C.T.

    AU - Meinhart, C. D.

    AU - Pennathur, S.

    N1 - ACS deal

    PY - 2019/3/7

    Y1 - 2019/3/7

    N2 - We present the most comprehensive two-dimensional numerical model to date for a nanoconfined bipolar electrochemical system. By accounting for the compact Stern layer and resolving the diffuse part of the electrical double layer at the bipolar electrode (BPE) surface and channel walls, our model captures the impact of surface polarization and ionic charge-screening effects on the heterogeneous charge-transfer kinetics, as well as nonlinear electrokinetic transport phenomena such as induced-charge electroosmosis and concentration polarization. We employ the Poisson-Nernst-Planck and Stokes flow system of equations, unified with generalized Frumkin-Butler-Volmer reaction kinetics, to describe water electrolysis reactions and the resulting transport of ions and dissolved gases in the confined BPE system. Our results demonstrate that under a sufficiently large applied electric field, the rapid reaction kinetics on our Pt BPE dynamically transition from charge-transfer-limited to mass-transfer-limited temporal regimes as regions depleted of redox species form and propagate outward from the respective BPE poles. This phenomenon was visualized experimentally with a pH-sensitive fluorescein dye and showed excellent phenomenological agreement with our numerical calculations, providing a foundation for further understanding and developing bipolar electrochemical processes in confined geometries. We introduce two prospective applications arising from our work: (1) a hybrid hydrodynamic/electrochemical peristaltic pump and (2) deducing information about chemical kinetics through simulation.

    AB - We present the most comprehensive two-dimensional numerical model to date for a nanoconfined bipolar electrochemical system. By accounting for the compact Stern layer and resolving the diffuse part of the electrical double layer at the bipolar electrode (BPE) surface and channel walls, our model captures the impact of surface polarization and ionic charge-screening effects on the heterogeneous charge-transfer kinetics, as well as nonlinear electrokinetic transport phenomena such as induced-charge electroosmosis and concentration polarization. We employ the Poisson-Nernst-Planck and Stokes flow system of equations, unified with generalized Frumkin-Butler-Volmer reaction kinetics, to describe water electrolysis reactions and the resulting transport of ions and dissolved gases in the confined BPE system. Our results demonstrate that under a sufficiently large applied electric field, the rapid reaction kinetics on our Pt BPE dynamically transition from charge-transfer-limited to mass-transfer-limited temporal regimes as regions depleted of redox species form and propagate outward from the respective BPE poles. This phenomenon was visualized experimentally with a pH-sensitive fluorescein dye and showed excellent phenomenological agreement with our numerical calculations, providing a foundation for further understanding and developing bipolar electrochemical processes in confined geometries. We introduce two prospective applications arising from our work: (1) a hybrid hydrodynamic/electrochemical peristaltic pump and (2) deducing information about chemical kinetics through simulation.

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