Experimental techniques for electrode kinetics – non-stationary methods

Abstract

In electrochemical kinetics, the electrode potential is the most important variable that is controlled by the experimentalist, and the current is usually measured as the response. Ideally, one would like to measure current and potential at constant, well-determined concentrations of the reactants. However, generally the concentrations of the reacting species at the interface are different from those in the bulk, since they are depleted or accumulated in the course of the reaction. So one must determine the interfacial concentrations. There are two principal ways of doing this. In the first class of methods one experimental variable, typically either the potential or the current, is kept constant or varied in a simple manner, the other observables are measured, and the surface concentrations are calculated by solving the transport equations under the conditions applied. In the simplest variant the overpotential or the current is stepped from zero to a constant value; the transient of the other variable is recorded and extrapolated back to the time at which the step was applied, when the interfacial concentrations were not yet depleted. This is the class of techniques that we cover in this chapter.