The galvanostatic single-pulse and the coulostatic impulse methods for the determination of the rate constants of electrode reactions

Abstract

The information on kinetic parameters of electrode reactions obtained with the galvanostatic single-step, the coulostatic impulse and the faradaic impedance methods is examined as a function of the applied electrolysis time and the ac frequency. A time and a frequency condition is given for which the information on kinetics obtainable with these methods is maximal. In the usual approach to the single-step and the coulostatic impulse methods these optimal conditions cannot be met. We present here a new procedure with which the experimental data measured with both methods can be interpreted exactly over the whole region of the η/t curve by means of numerical tables. The application of these tables enhances the limit of the applicability of the single-step method by a factor of 3 and that of the coulostatic impulse method by a factor of 100. The methods are applied to the Cd2+/Cd (Hg)-electrode in 1 M NaClO4 and the Hg22+/ Hg electrode in 1 M HClO4.