Electrolysis was performed in a 2-compartment glass H-cell with a ceramic separator. The cathode compartment housed a 0.25 cm 2 Teflon-coated carbon paper (AVCarb P50T) electrode loaded with ~4 mg cm -2 polymer, and a leakless Ag/AgCl reference electrode (eDAQ). In the anode compartment, Ni foam (MTI) was used as the counter electrode, and each compartment was filled with 5 mL 0.1 M KOH. Electrolytes were stirred and O2 was bubbled into the cathode test compartment throughout the experiment. At 20-minute intervals 600 μL aliquots of sample were collected from the cathode compartment and replaced with fresh electrolyte.