Destabilizing role of the double layer for a dissolution–depassivation mechanism

A new dissolution–depassivation mechanism showing a non-trivial complex S-shaped polarization curve due to the Frumkin isotherm hypothesis has been studied. A potential domain exists for sufficiently low values of the Frumkin interaction parameter where a negative differential resistance is observed. For this mechanism, the electrode potential acts as an essential system variable due to the double layer capacitance. Harmonic and relaxation oscillations can be observed for the dissolution–depassivation mechanism under galvanostatic control (GC). Hopf bifurcation gives rise to oscillations under GC only for sufficiently high values of the double layer capacitance. Bifurcation diagrams are plotted.