Concentrations of Electroactive Solutes, during Cyclic and Other Voltammetries, at Points Away from the Electrode Surface. 1. Fundamental Relationships and Their Validation.

There are circumstances in which it is useful to know the concentration, or its gradient, of an electroactive product or reactant at some distance from an electrode. Here it is demonstrated that this information is available, in principle, under conditions of semiinfinite planar diffusion, provided that the surface concentration and/or the current are known as functions of time. Several methods of calculation are explored, using the example of linear sweep voltammetry. Some of these methods rely on analytical formulations; others are purely numerical. Concordance of the results of the various methods provides validation of all. A method based on the convolution of the current is especially versatile.