A theoretical investigation of electrode oscillations

When certain electrodes are driven away from equilibrium by application of an external voltage, undamped oscillations of the voltage or current are observed. We develop here a simple theory for describing transport at the boundary of an electrode which is suitable for examining these oscillations. The theory involves the coupling between the electric field and diffusion of a reducible species near the electrode surface and includes certain effects of double layer relaxation. A simple reaction scheme which involves the reduction of an adsorbed cation is then used to produce electrochemical oscillations. The reduction rate is modeled by using the full Butler-Volmer equation and, when plausible values of transport coefficients and other parameters are used, electrochemical oscillations are obtained. The steady state and dynamical behavior of this model are examined by using graphical, analytical, and numerical methods. Some comments are made regarding the relationship of this work to experimentally observed oscillations.