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Finite element modeling of the combined faradaic and electrostatic contributions to the voltammetric response of monolayer redox films
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Levey, Katherine J., Edwards, Martin A., White, Henry S. and Macpherson, Julie V. (2022) Finite element modeling of the combined faradaic and electrostatic contributions to the voltammetric response of monolayer redox films. Analytical Chemistry, 94 (37). pp. 12673-12682. doi:10.1021/acs.analchem.2c01976 ISSN 0003-2700.
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Official URL: http://dx.doi.org/10.1021/acs.analchem.2c01976
Abstract
The voltammetric response of electrodes coated with a redox-active monolayer is computed by finite element simulations based on a generalized model that couples the Butler–Volmer, Nernst–Planck, and Poisson equations. This model represents the most complete treatment of the voltammetric response of a redox film to date and is made accessible to the experimentalist via the use of finite element modeling and a COMSOL-generated report. The model yields a full description of the electric potential and charge distributions across the monolayer and bulk solution, including the potential distribution associated with ohmic resistance. In this way, it is possible to properly account for electrostatic effects at the molecular film/electrolyte interface, which are present due to the changing charge states of the redox head groups as they undergo electron transfer, under both equilibrium and nonequilibrium conditions. Specifically, our numerical simulations significantly extend previous theoretical predictions by including the effects of finite electron-transfer rates (k0) and electrolyte conductivity. Distortion of the voltammetric wave due to ohmic potential drop is shown to be a function of electrolyte concentration and scan rate, in agreement with experimental observations. The commonly used Laviron analysis for the determination of k0 fails to account for ohmic drop effects, which may be non-negligible at high scan rates. This model provides a more accurate alternative for k0 determination at all scan rates. The electric potential and charge distributions across an electrochemically inactive monolayer and electrolyte solution are also simulated as a function of applied potential and are found to agree with the Gouy-Chapman-Stern theory.
Item Type: | Journal Article | ||||||||||||
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Subjects: | Q Science > QD Chemistry T Technology > TP Chemical technology |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry | ||||||||||||
Library of Congress Subject Headings (LCSH): | Electrodes, Electrochemistry, Self-assembly (Chemistry) | ||||||||||||
Journal or Publication Title: | Analytical Chemistry | ||||||||||||
Publisher: | American Chemical Society | ||||||||||||
ISSN: | 0003-2700 | ||||||||||||
Official Date: | 20 September 2022 | ||||||||||||
Dates: |
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Volume: | 94 | ||||||||||||
Number: | 37 | ||||||||||||
Page Range: | pp. 12673-12682 | ||||||||||||
DOI: | 10.1021/acs.analchem.2c01976 | ||||||||||||
Status: | Peer Reviewed | ||||||||||||
Publication Status: | Published | ||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | ||||||||||||
Date of first compliant deposit: | 12 September 2022 | ||||||||||||
Date of first compliant Open Access: | 12 September 2022 | ||||||||||||
RIOXX Funder/Project Grant: |
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