Performance of a PEM fuel cell cathode catalyst layer under oscillating potential and oxygen supply

A model for impedance of a PEM fuel cell cathode catalyst layer under simultaneous application of potential and oxygen concentration perturbations is developed and solved. The resulting expression demonstrates dramatic lowering of the layer impedance under increase in the amplitude of the oxygen concentration perturbation. In–phase oscillations of the overpotential and oxygen concentration lead to formation of a fully transparent to oxygen sub–layer. This sub–layer works as an ideal non polarizable electrode, which strongly reduces the system impedance.