To determine the electrolyte uptake and swelling, circular samples with a diameter of 1 cm were dried in a vacuum oven at 60 ℃ overnight. The weight of the dried samples (Wdry) was measured. Subsequently, the samples were immersed in vials containing solutions of aqueous KOH with concentrations ranging from 5 to 25 wt% for 24 h. Afterward, the samples were carefully blotted with a lint-free cloth to remove excess liquid and weighed again to obtain the electrolyte-imbibed membrane weight (Wwet). The electrolyte uptake (EU) was calculated using Equation . Polarization curves were recorded stepwise with a duration of 60 s at each current density setpoint. Prior to recording the polarization curves, the system was activated for 24 h at a constant current density of 100 mA cm -2 . EIS was performed using a VersaStat 4 potentiostat in potentiostatic mode at a potential of 1.3 V. The frequency range for EIS measurements was from 100 kHz to 1 Hz with an amplitude of 10 mV. The cell operated at a constant current density of 100 mA cm -2 during the intervals between the polarization experiments and EIS measurements.