Theory of Cyclic Voltammetry at Microdisk Electrodes

The cyclic voltammetric response, which is obtained by measurements at microdisk electrodes (R ± 1 mm), may deviate strongly from theoretical predictions. The cause of such effects is due to nonlinear diffusion processes, which, in principle, are present at unshielded disk electrodes. They increase with diminishing electrode radii and slow scan rates in accordance with the value of the dimensionless parameter = (D/aR2)1/2. A quantitative description of nonlinear mass transport to microdisk electrodes can be achieved with the aid of a two‐dimensional simulation based on an implicit difference approximation. The agreement with experimental data is very close. The reversible and the quasi‐reversible charge transfer is discussed. To facilitate the interpretation of cyclic voltammograms, working‐curves and diagnostic criteria are presented.