Square Wave Voltammetry for Two-Step Surface Reductions
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- 作者：John J. O'Dea and Janet G. Osteryoung
- 刊名：Analytical Chemistry
- 出版年：1997
- 出版时间：February 15, 1997
- 年：1997
- 卷：69
- 期：4
- 页码：650 - 658
- 全文大小：226K
- 年卷期：v.69,no.4(February 15, 1997)
- ISSN：1520-6882
文摘
Strongly adsorbed species on an electrode surface areused to create a stable, redox-modified surface.Squarewave voltammetry is then used to degrade the surfaceelectrochemically, as evidenced by the resulting voltammetric response. This process can be mathematicallymodeled as a quasi-reversible surface reaction coupledwith a first-order irreversible surface reaction of theproduct. This is the simplest possible model that canexplain a two-step surface reduction. Exemplarycalculations for square wave voltammetry show a wide variety ofpeak shapes depending on rate constants and square waveamplitude. The reduction of Dimethyl Yellow(4-(dimethylamino)azobenzene) adsorbed on mercury is accuratelydescribed by this model. Characteristic parameters oftheoverall surface process are obtained from voltammogramsby using the two-step model with nonlinear least-squaresanalysis (COOL). For Dimethyl Yellow in Britton-Robinson buffer (pH 6.00) at a surface concentration of 17.3pmol cm-2, these parameters are as follows:standardpotential, E10 = -0.397 ±0.001 V vs SCE; transfercoefficient for the first step, 
1 = 0.43 ± 0.02;rateconstant for the first step, k10 =103 ± 8 s-1; transfercoefficient for the second step, 2 = 0.11 ± 0.04;andrate constant for the second step,k20 (referenced toE10)= 11.1 ± 1.7 s-1. Uncertainties are95% confidenceintervals derived from a pool of 11 voltammogramscollected at different square wave amplitudes(Esw =0-100 mV).
1 = 0.43 ± 0.02;rateconstant for the first step, k10 =103 ± 8 s-1; transfercoefficient for the second step, 2 = 0.11 ± 0.04;andrate constant for the second step,k20 (referenced toE10)= 11.1 ± 1.7 s-1. Uncertainties are95% confidenceintervals derived from a pool of 11 voltammogramscollected at different square wave amplitudes(Esw =0-100 mV).