Modeling galvanostatic potential oscillations in the electrocatalytic iodate reduction system

An experimental and theoretical description of the oscillatory electrocatal ytic iodate reduction system in alkaline solution is presented. Experimenta l measurements suggested the crucial role of a negative differential resist ance as well as the presence of hydrogen evolution in the oscillatory insta bility. A simple kinetic model with one chemical species was developed whic h involved: (i) an iodate reduction current with N-shaped potential depende nce due to a Frumkin repulsion effect; and (ii) an additional 'iodate-indep endent' current providing process. The dynamical behavior of the model comp ares favorably with experiments as far as voltammetric profiles, stirring e ffects and bifurcations between stable and oscillatory states are concerned . It is further shown that the model can account for oscillatory states in a number of related electrocatalytic systems. (C) 1999 Elsevier Science S.A . All rights reserved.