Instabilities in electrochemistry

The occurrence of instabilities in the temporal evolution of electrochemical processes generally manifests itself by producing potential or current time-oscillations with more or less regular features, or by displaying spatiotemporal patterns at the electrode surface and in the electrolyte. It is remarkable that almost every electrochemical reaction can undergo a transition towards a situation of kinetic instability if appropriate conditions are met. Such phenomena are a consequence of the irreversible departure of the system here defined as the combination of the electrodes with the electrolyte traversed by an electrical current, from an initial state which is intrinsically unstable, after being disturbed by a perturbation which alters a parameter characterizing the state of the system. From this it descends that the analysis of the stability of an electrochemical system against perturbations should start firstly with the definition of all variables controlling the stability of the system.