Gareth Kennedy

data scientist and mathematical modeller

 

Electrochemistry Page

Contents

Research overview
Electrochemistry modelling
Large amplitude FT
Links


Research overview

My primary research interest in electrochemistry is the computational modelling of complex electrochemical systems. These systems basically consist of some substances in solution (or attached to the electrode surface) interacting with each other and with a changing electrical potential at the surface of an electrode. From a mathematical point of view this is a strongly coupled system consisting of an electrical circuit, the transport of concentrations near the electrode and a system of reactions describing the interaction between concentrations.

The main result of my work in this field is the development of the software package MECSim done while working at the Monash Electrochemistry Group at Monash University, Melbourne, Australia.


Electrochemistry modelling

One of the most widely used electroanalytical methods in analytical chemistry is dc cyclic voltammetry. This consists of the application of a voltage as a function of time to produce a current response. In the case of cyclic voltammetry a typical example of this voltage is shown below left. The time dependent current response is shown below right, where in this case the increasing magnitude of the current is due to an increasing concentration.

The current response to the applied voltage is typically visualised as a voltammogram (shown right). The peak currents and the voltages at which they occur can be used to give information about the concentrations and rate constants. However, this method often does not allow a full determination of all free parameters for a given electrochemical mechanism.

Herein lies another problem, often the actual mechanism is unknown to begin with. In these cases being able to get the most amount of information from a single experiment is of great use...


Large amplitude FT

The technique of large amplitude Fourier Transform AC voltammetry uses multiple ac sinusoidal waveforms added to the dc ramp in the applied voltage. This allows multiple timescales for the electrochemical system to be probed simultaneously. This is very useful when many chemical reactions are occurring at once, since the rate constants can be disentangled.

The Monash Electrochemical Simulation package (MECSim) was developed by myself as a general problem solver of large amplitude Fourier Transform AC voltammetry for all solution phase mechanisms involving different forms of electron transfer coupled with any combination of chemical reaction and with a range of electrode geometries. An example of distinguishing three different mechanisms is shown below. On the left is the dc component of the resultant current response and on the right is the current amplitude of the first harmonic (the fundamental) as a function of time. The analysis of different harmonics makes extracting information about various chemical processes much easier than a single dc experiment, or series of them.


Links

Monash Electrochemistry Group
Department of Computer Science, Oxford
Monash eScience and Grid Engineering Laboratory
School of Mathematical Sciences, Monash University


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