ROTATING-DISK ELECTRODE VOLTAMMETRY - WAVESHAPE ANALYSIS FOR DISP2 AND EC2 PROCESSES

Journal article

Theory is presented for the shape of current-voltage curves measured at a rotating-disc electrode for the cases where the substrate reacts either via a DISP2 or an EC2 process, and in which the kinetic step is sufficiently fast to allow the use of the reaction layer concept in the mathematical analysis of the problem. It is predicted that if the measured voltammetric waves are analysed using an ordinary Tafel plot (corrected in the usual way for mass transport), then significant curvature will result, the extent of which depends on the rate constant of the chemical step following the first electron transfer. In principle this curvature of the Tafel plot permits the deduction of the second-order rate constant describing the following reaction. Additionally the half-wave potential of the voltammetric wave is found to vary by (ca.) 20 mV per decade of change in rotation speed (at 25 °C). This again allows the deduction of kinetic parameters, although in this case the appropriate formal potential for the first electron transfer must be known from some other measurement. In the case of the DISP2 mechanism the kinetics can also be deduced by studying the effective number of electrons transferred as a function of electrode rotation speed. An appropriate working curve is presented for the conditions where the reaction layer treatment may be taken to be valid.

Authors: Compton, R; Mason, D; Unwin, P

• Publication status: Published
• Journal: JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I
• Volume: 84
• Issue: 2
• Pages: 473-482
• Publication date: 1988-01-01
• DOI: 10.1039/f19888400473
• ISSN: 0300-9599
• Language: English