Theoretical Analysis of the Relative Significance of Thermodynamic and Kinetic Dispersion in the dc and ac Voltammetry of Surface-Confined Molecules
AuthorsMorris, Graham P.
Baker, Ruth E.
Davis, Jason J.
Gavaghan, David J.
Bond, Alan M.
KAUST Grant NumberKUK-C1-013-04
MetadataShow full item record
Abstract© 2015 American Chemical Society. Commonly, significant discrepancies are reported in theoretical and experimental comparisons of dc voltammograms derived from a monolayer or close to monolayer coverage of redox-active surface-confined molecules. For example, broader-than-predicted voltammetric wave shapes are attributed to the thermodynamic or kinetic dispersion derived from distributions in reversible potentials (E<sup>0</sup>) and electrode kinetics (k<sup>0</sup>), respectively. The recent availability of experimentally estimated distributions of E<sup>0</sup> and k<sup>0</sup> values derived from the analysis of data for small numbers of surface-confined modified azurin metalloprotein molecules now allows more realistic modeling to be undertaken, assuming the same distributions apply under conditions of high surface coverage relevant to voltammetric experiments. In this work, modeling based on conventional and stochastic kinetic theory is considered, and the computationally far more efficient conventional model is shown to be equivalent to the stochastic one when large numbers of molecules are present. Perhaps unexpectedly, when experimentally determined distributions of E<sup>0</sup> and k<sup>0</sup> are input into the model, thermodynamic dispersion is found to be unimportant and only kinetic dispersion contributes significantly to the broadening of dc voltammograms. Simulations of ac voltammetric experiments lead to the conclusion that the ac method, particularly when the analysis of kinetically very sensitive higher-order harmonics is undertaken, are far more sensitive to kinetic dispersion than the dc method. ac methods are therefore concluded to provide a potentially superior strategy for addressing the inverse problem of determining the k<sup>0</sup> distribution that could give rise to the apparent anomalies in surface-confined voltammetry.
CitationMorris GP, Baker RE, Gillow K, Davis JJ, Gavaghan DJ, et al. (2015) Theoretical Analysis of the Relative Significance of Thermodynamic and Kinetic Dispersion in the dc and ac Voltammetry of Surface-Confined Molecules. Langmuir 31: 4996–5004. Available: http://dx.doi.org/10.1021/la5042635.
SponsorsThis publication is based on work supported by award no. KUK-C1-013-04, made by King Abdullah University of Science and Technology (KAUST). Financial support from the Australian Research Council is also gratefully acknowledged.
PublisherAmerican Chemical Society (ACS)
CollectionsPublications Acknowledging KAUST Support
- Novel kinetic and background current selectivity in the even harmonic components of fourier transformed square-wave voltammograms of surface-confined azurin.
- Authors: Zhang J, Guo SX, Bond AM, Honeychurch MJ, Oldham KB
- Issue date: 2005 May 12
- Theoretical analysis of the two-electron transfer reaction and experimental studies with surface-confined cytochrome c peroxidase using large-amplitude Fourier transformed AC voltammetry.
- Authors: Stevenson GP, Lee CY, Kennedy GF, Parkin A, Baker RE, Gillow K, Armstrong FA, Gavaghan DJ, Bond AM
- Issue date: 2012 Jun 26
- Systematic evaluation of electrode kinetics and impact of surface heterogeneity for surface-confined proteins using analysis of harmonic components available in sinusoidal large-amplitude Fourier transformed ac voltammetry.
- Authors: Lee CY, Fleming BD, Zhang J, Guo SX, Elton DM, Bond AM
- Issue date: 2009 Oct 12
- Application of power spectra patterns in Fourier transform square wave voltammetry to evaluate electrode kinetics of surface-confined proteins.
- Authors: Fleming BD, Barlow NL, Zhang J, Bond AM, Armstrong FA
- Issue date: 2006 May 1
- A comparison of the higher order harmonic components derived from large-amplitude Fourier transformed ac voltammetry of myoglobin and heme in DDAB films at a pyrolytic graphite electrode.
- Authors: Lee CY, Bond AM
- Issue date: 2010 Apr 6