Electrochemical gas adsorption experiments. The device was charged with a protocol adapted from Zhu et al. A constant current (30 mA / g of the gas-exposed electrode) was applied until a target cell potential between the electrodes was reached. This potential was then held for 30 minutes (to give more time to equilibrate), then a 30 mA/g constant current applied to return the system to the initial potential, and a final 30 minute potential holding step. This procedure was repeated for the desired number of cycles.