The Electrochemical Response of a Disk Electrode to Angular Velocity Steps

Abstract

An experimental study has verified the prediction that the establishment of a boundary layer at the surface of an impulsively started disk is complete in less than three tenths of a rotation. A similar result was found for a ro-tating disk electrode whose speed was stepped between two values. The cur-rent transient produced by a step change of the rotation speed of a disk elec-trode held in the convective-diffusion limiting current region of some elec-troactive species has been derived. Studies of the reduction of Ag +, Fe 3+, and Hg2 2+ are in good agreement with theory and show that the relaxation process is limited by the convective-diffusion of the electroactive species rather than the hydrodynamic relaxation phenomenon. Heretofore, nonsteady-state studies using the rotat-ing disk electrode have been carried out at constant angular velocity by perturbing the potential and mea-suring the t ime-dependent current response, or vice