Parameter recovery in AC solution-phase voltammetry and a consideration of some issues arising when applied to surface-confined reactions

Thesis

A major problem in the quantitative analysis of AC voltammetric data has been the variance in results between laboratories, often resulting from a reliance on "heuristic" methods of parameter estimation that are strongly dependent on the choices of the operator. In this thesis, an automatic method for parameter estimation will be tested in the context of experiments involving electron-transfer processes in solution-phase. It will be shown that this automatic method produces parameter estimates consistent with those from other methods and the literature in the case of the ferri-/ferrocyanide couple, and is able to explain inconsistency in published values of the rate parameter for the ferrocene/ferrocenium couple. When a coupled homogeneous reaction is considered in a theoretical study, parameter recovery is achieved with a higher degree of accuracy when simulated data resulting from a high frequency AC voltammetry waveform are used.

When surface-confined reactions are considered, heterogeneity in the rate constant and formal potential make parameter estimation more challenging. In the final study, a method for incorporating these "dispersion" effects into voltammetric simulations is presented, and for the first time, a quantitive theoretical study of the impact of dispersion on measured current is undertaken.

Authors: Morris, GP

• Publication date: 2014
• DOI: 10.5287/ora-rdk6zwpxm
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: mathematical modelling; AC voltammetry; parameter estimation; numerical solutions; voltammetry; inverse problems; electrochemistry
• Subjects: Electrochemistry and electrolysis; Mathematics; Partial differential equations; Computational chemistry; Biology and other natural sciences (mathematics)