Elucidating capacitance and resistance terms in confined electroactive molecular layers
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Data
2013-01-02
Autores
Bueno, Paulo Roberto [UNESP]
Fabregat-Santiago, Francisco
Davis, Jason J.
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Resumo
Electrochemical analyses on confined electroactive molecular layers, herein exemplified with electroactive self-assembled monolayers, sample current contributions that are significantly influenced by additional nonfaradaic and uncompensated resistance effects that, though unresolved, can strongly distort redox analysis. Prior work has shown that impedance-derived capacitance spectroscopy approaches can cleanly resolve all contributions generated at such films, including those which are related to the layer dipolar/electrostatic relaxation characteristics. We show herein that, in isolating the faradaic and nonfaradaic contributions present within an improved equivalent circuit description of such interfaces, it is possible to accurately simulate subsequently observed cyclic voltammograms (that is, generated current versus potential patterns map accurately onto frequency domain measurements). Not only does this enable a frequency-resolved quantification of all components present, and in so doing, a full validation of the equivalent circuit model utilized, but also facilitates the generation of background subtracted cyclic voltammograms remarkably free from all but faradaic contributions. © 2012 American Chemical Society.
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Capacitance spectroscopy, Circuit description, Cyclic voltammograms, Electroactive, Electrochemical analysis, Equivalent circuit model, Frequency domain measurement, Molecular layer, Self assembled monolayers, Capacitance
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Analytical Chemistry, v. 85, n. 1, p. 411-417, 2013.