INFLUENCE OF DOUBLE-LAYER CHARGING IN CHRONOPOTENTIOMETRY

A rigorous theoretical treatment of chronopotentiometry is presented which includes double-layer charging. The treatment is based on a model that assumes reversible charge transfer and a potential-independent double-layer capacitance. The procedures for treating this model easily are extended to more complicated models. Results of theoretical calculations are presented as ratios of faradaic to total current and as theoretical potential-time curves. These potential-time curves are used to evaluate several methods of transition-time measurement, and it is concluded that the method of Laity and McIntyre is excellent for compensating effects of double-layer charging. In addition, several diagnostic methods often used to analyze chronopotentiometric data are discussed in relation to the theoretical calculations. Finally, the case of current reversal is treated, and the effect of double-layer charging on the ratio of forward to reverse transition times is determined.