A comparison of simulated and experimental voltammograms obtained for the [Fe(CN)₆]^3-/4- couple in the absence of added supporting electrolyte at a rotating disk electrode

The voltammetric behavior of the [Fe(CN)₆]^3-/4- couple at a glassy carbon rotating macrodisk electrode without added supporting electrolyte is shown to be in close to ideal agreement with the theory presented over a wide range of electrode rotation and scan rates when the concentration of electroactive species used is 50 mM. The influences of migration, uncompensated resistance, heterogeneous charge-transfer kinetics, and inhomogeneous diffusion are shown to be well modeled by a finite difference simulation scheme that affords excellent agreement between experiment and theory. The use of the rotating disk electrode, even when only moderate rotation rates are employed, is shown to eliminate the problem with natural convection that exists when using stationary electrodes (macro- or microdisk) and that is enhanced in the absence of added supporting electrolyte. Consequently, it has been concluded that the rotating disk electrode method represents an almost ideal technique for conducting studies without added supporting electrolyte.