Journal article
Cyclic Voltammetric Diagnostics for Inert, Uniform Density Films
Journal of the Electrochemical Society, Vol.160(6), pp.H285-H293
2013
DOI: 10.1149/2.025306jes
Abstract
Quantitative characterization of uniform density, electrochemically inert films on electrodes is achieved by cyclic voltammetry (CV) of a redox probe that partitions from electrolyte into the film. Electrochemically inert films generate no faradaic current in the voltammetric window of the probe. In simulation models, probes pre-equilibrate into films, electrolyze at electrodes, diffuse in film and solution, and extract across film solution interfaces. Film thickness is ℓ. Diffusion length δ approximates distance from the electrode where voltammetry perturbs probe concentration; δ∝ν− 1/2 for scan rate ν. At high ν, δ < ℓ and voltammetric morphologies are typical of semi-infinite linear diffusion. As ν slows, δ gsim ℓ and CV morphologies can change with relative probe flux in the film and solution. For higher solution flux, voltammograms assume sigmoidal (S-shaped) characteristics; higher film flux generates gaussian (thin layer CV) characteristics. For film and solution diffusion coefficients Df and Ds and κ the equilibrium ratio of probe concentration in film to solution, diagnostics yield κ√(Df/Ds) and ℓ2/Df. Because diagnostics apply for all ν, films are fully parameterized by CV alone. Without these diagnostics, full characterization requires a second, steady state voltammetric measurement. Diagnostics are vetted with [Ru(bpy)3]2 + (probe) in inert polymer films of Nafion and of poly(styrenesulfonate).
Details
- Title: Subtitle
- Cyclic Voltammetric Diagnostics for Inert, Uniform Density Films
- Creators
- Krysti L KnocheChaminda HettigePaul D MobergSudath AmarasingheJohna Leddy
- Resource Type
- Journal article
- Publication Details
- Journal of the Electrochemical Society, Vol.160(6), pp.H285-H293
- DOI
- 10.1149/2.025306jes
- ISSN
- 0013-4651
- eISSN
- 1945-7111
- Language
- English
- Date published
- 2013
- Academic Unit
- Chemistry
- Record Identifier
- 9983985851202771
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