Step 10, 11 - Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV)

For the CV, the cell was cycled 5 times between 0.05 and 0.95 V at 100 mV s⁻¹ scan rate, with 1 NLPM H₂ on the anode and no flow in the cathode. The measurement was performed at 80 °C and 100% RH at atmospheric pressure. Prior to the voltage cycling, the cell was conditioned for 15 minutes in the mentioned conditions. Afterwards, the ECSA was obtained by averaging the H₂ adsorption and desorption charge, and the double layer capacity was evaluated at the minimum in the region between 0.3 and 0.6 V⁴⁶. CVs were conducted in each aging step from 0 to 30k cycles. Figure 5 displays an exemplary CV dataset of test run 2. The LSV was performed in the same conditions, only with 1 NLPM N₂ on the cathode, and a potential sweep from 0.1 to 0.5 V with 1 mV s⁻¹ scan rate. The H₂ crossover current was evaluated as the current at 200 mV in a linear fit of the LSV curve between 0.3 and 0.5 V⁴⁷.

Cyclic voltammetry and evaluated ECSA and double layer capacity over time for cell 2 (I/C 0.8, EW 790 g mol⁻¹, 50 wt% Pt/C on HSA carbon, UPL 0.95 V @ 100% RH).