Modelling of spatiotemporal patterns during metal electrodissolution in a cell with a point reference electrode

A model for the simulation of experimentally observed spatiotemporal patterns in the bistable and oscillatory regions during the electrodissolution of metals under potentiostatic control is presented. A two-dimensional geometry was used with a point-like reference electrode located in the electrolyte between the working and the counter electrodes. The dynamical variables of the model are the potential drop across the electric double layer and the proton concentration near the working electrode surface. The effects of changing parameter values such as cell geometry, electrolyte conductivity, and double layer capacitance on time series and spatial patterns are presented. In a bistable system the reference electrode position influences both the front behavior and also the structure (uniform or nonuniform) of the steady state. In the oscillatory region the direction of the passivation wave can be changed by changes in the location of the reference electrode. An increase in electrode length can change a periodic oscillation with almost uniform spatial distribution to a chaotic behavior with nonuniform pattern.