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Identification of surface heterogeneity effects in cyclic voltammograms derived from analysis of an individually addressable gold array electrode
journal contribution
posted on 2008-05-15, 00:00 authored by C Y Lee, Mike Yongjun TanMike Yongjun Tan, A BondVoltammetric behavior at gold electrodes in aqueous media is known to be strongly dependent on electrode polishing and history. In this study, an electrode array consisting of 100 nominally identical and individually addressable gold disks electrodes, each with a radius of 127 µm, has been fabricated. The ability to analyze both individual electrode and total array performance enables microscopic aspects of the overall voltammetric response arising from variable levels of inhomogeneity in each electrode to be identified. The array configuration was initially employed with the reversible and hence relatively surface insensitive [Ru(NH3)6]3+/2+ reaction and then with the more highly surface sensitive quasi-reversible [Fe(CN)6]3−/4− process. In both these cases, the reactants and products are solution soluble and, at a scan rate of 50 mV s−1, each electrode in the array is assumed to behave independently, since no evidence of overlapping of the diffusion layers was detected. As would be expected, the variability of the individual electrodesʼ responses was significantly larger than found for the summed electrode behavior. In the case of cytochrome c voltammetry at a 4,4′-dipyridyl disulfide modified electrode, a far greater dependence on electrode history and electrode heterogeneity was detected. In this case, voltammograms derived from individual electrodes in the gold array electrode exhibit shape variations ranging from peak to sigmoidal. However, again the total response was always found to be well-defined. This voltammetry is consistent with a microscopic model of heterogeneity where some parts of each chemically modified electrode surface are electroactive while other parts are less active. The findings are consistent with the common existence of electrode heterogeneity in cyclic voltammetric responses at gold electrodes, that are normally difficult to detect, but fundamentally important, as electrode nonuniformity can give rise to subtle forms of kinetic and other forms of dispersion.
History
Journal
Analytical chemistryVolume
80Issue
10Pagination
3873 - 3881Publisher
American Chemical SocietyLocation
Washington, D. C.Publisher DOI
ISSN
0003-2700eISSN
1520-6882Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2008, American Chemical SocietyUsage metrics
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cyclic voltammetryelectrolytic polishinggoldkineticsmathematical modelsmicroscopic examinationScience & TechnologyPhysical SciencesChemistry, AnalyticalChemistryWIRE BEAM ELECTRODEPARTIALLY COVERED ELECTRODESSELF-ASSEMBLED MONOLAYERSHEART CYTOCHROME-CELECTROCHEMICAL CHARACTERIZATIONSPECTROELECTROCHEMICAL ANALYSISELECTROCATALYTIC BEHAVIORMICROELECTRODE ARRAYSPLATINUM-ELECTRODETRANSFER KINETICS
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