Analysis of Damjanović kinetics of the oxygen reduction reaction: Stability, polarization curve and impedance spectra

• Damjanović ORR kinetics are analyzed; two steady-state solutions are found.
• One of the solutions is absolutely unstable, while the other is stable.
• The polarization curve exhibits the “breaking” limiting current density.
• An analytical expression for the catalyst layer impedance is derived.

We report analysis of equations describing Damjanović kinetics of the oxygen reduction reaction. Analytical expressions for two steady-state solutions are found. Stability analysis shows that one of this solutions is stable, while the other is absolutely unstable in the whole range of parameters. The polarization curve corresponding to the stable solution exhibits the effect of limiting current density j0lim. Unlike an usual asymptotic approach to the limiting current, here j0lim marks a “break” of the curve. An analytical model of the cathode catalyst layer impedance based on the Damjanović dynamics of surface coverages is developed.