Determination of Electrochemical Electron‐Transfer Reaction Standard Rate Constants at Nanoelectrodes: Standard Rate Constants for Ferrocenylmethyltrimethylammonium(III)/(II) and Hexacyanoferrate(III)/(II)

Abstract

The most common approximation of electroneutrality is inappropriate for analyzing the voltammetric response of nanoelectrodes. Therefore, the microelectrode theory for extracting the standard rate constant k 0 for electron transfer from steady-state voltammograms is invalid for nanoelectrodes. Unlike previous approaches, we considered the influence of the interfacial potential distribution caused by the absence of electroneutrality. We estimated the magnitude of the error at low overpotential incurred as a result of ignoring the absence of electroneutrality and found that it was small. In this region, electrochemical reaction appears to be limited by the rate of electron transfer. Under these conditions, k 0 can be obtained from steady-state voltammogram data in a low overpotential region according to an approximate form of the Butler -Volmer equation. This procedure can greatly simplify analysis and calculation of the rate constant k 0 at nanoelectrodes.

Pollutant toxicity and detoxification by humic substances: mechanisms and quantitative assessment via luminescent biomonitoring

“…Potassium ferricyanide, K 3 [Fe(CN) 6 ], was chosen as a model oxidizer because of its stability in water solution (in contrast to unclustered iron salts) and monoelectron oxidative transition Fe 3+ /Fe 2+ (Katafias et al 2008;Zhang et al 2008). Detoxification coefficients D IT and D OxT were calculated to characterize changes in integral toxicity (IT) and oxidative toxicity (OxT) under the action of HS (Tarasova et al 2011).…”

Effect of humic substances on toxicity of inorganic oxidizer bioluminescent monitoring

“…The value DI was chosen to evaluate the general toxicity, and T 0. 5 [27,28]. We studied the detailed chemical processes taking place in the enzyme system sensitive to oxidizers.…”

Gold nanowire electrodes in array: simulation study and experiments

“…Historically, experiments undertaken to determine k 0 using macro and ultra-microelectrodes have been diffusion limited as such that low values have been reported. [8][9][10][11] The advent of nanoscale electrodes have eliminated diffusion effects and permitted higher (truer) values to be experimentally determined. 22 Kinetic analysis is undertaken on steady-state CVs of a single electron oxidation of FcCOOH at arrays of three nanowires separated by 5 and 15 mm.…”

“…6,7 Consequently, 1-D nanostructures have been employed to explore heterogeneous electron transfer rate constants with rates up to two orders of magnitude higher than previously measured, which are being reported. [8][9][10][11] In addition, electrochemical devices employing discrete nanowire sensors demonstrating highly sensitive detection of key biomolecules including dopamine, 7 hydrogen peroxide 12 and glucose 13 amongst others have recently been reported. Electrodes based on nanowire arrays offer the potential for further enhancements in electroanalysis including: increased signal to noise ratio and increased sensitivity while also allowing quantitative detection at much lower concentrations.…”

“…Historically, experiments undertaken to determine k 0 using macro and ultra-microelectrodes have been diffusion limited as such that 55 low values have been reported. [8][9][10][11] The advent of nanoscale electrodes have eliminated diffusion effects and permitted higher (truer) values to be experimentally determined [21]. To explore how much diffusional overlap may affect the extraction of the heterogeneous rate of electron transfer, we 65 employed a three parameter fit to extract the k 0 values from cyclic voltammograms obtained using nanowire arrays (5 mV.s -1 ) separated by 5 µm and 15 µm, respectively.…”