Identification of surface heterogeneity effects in cyclic voltammograms derived from analysis of an individually Addressable Gold Array Electrode.
MetadataShow full item record
Copyright © 2008 American Chemical Society
The website of Analitical Chemistry is available at: http://pubs.acs.org/journal/ancham
Open access to this article will be available 12 months after publication via the website of the American Chemical Society. http://acswebcontent.acs.org/home.html
Voltammetric 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 m, 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 electrodes 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.
Showing items related by title, author, creator and subject.
Chenrai, Piyaphong (2008)The Comet Gold Mine is in the Murchison mineral field which lies within the Yilgarn Craton of Western Australia. Several different geophysical methods were used in this study to define the geophysical signatures of ...
Chester, Ryan (2007)The first part of this thesis reports the synthesis of five calixarene molecules and their incorporation into ISEs as thallium(I) selective ionophores for use in clinical and environmental analysis. Four calixarene ...
Fast responding hydrogen gas sensors using platinum nanoparticle modified microchannels and ionic liquidsHussain, Ghulam; Ge, M.; Zhao, C.; Silvester-Dean, Debbie (2019)© 2019 Elsevier B.V. From a safety perspective, it is vital to have fast responding gas sensors for toxic and explosive gases in the event of a gas leak. Amperometric gas sensors have been developed for such a purpose, ...