Oscillating Oxygen Concentration Transport through PEM Fuel Cell Gas Diffusion Layer: Variation of the Phase Angle

Recently, it was shown that performance of the cathode catalyst layer in a PEM fuel cell dramatically improves if the oxygen concentration (OC) at the catalyst/gas diffusion layer (GDL) interface oscillates in--phase with the overpotential. However, OC oscillations could only be organized in the cathode channel. Does transport through the GDL affect the phase angle of OC oscillations? Below, it is shown that at frequencies below 1 Hz, the GDL does not change this phase angle. At high frequencies, the phase angle after transport through the GDL is $-3\pi/4$ regardless of the GDL transport parameters.