Experiments were conducted in a flow cell with a working area of 4 cm 2 and an electrolyte of 1M LiBF4 in diglyme with varying ethanol concentrations (0.25 vol. % -1.0 vol. %). The electrodes were a Freudenberg H15 cathode, Pt wire pseudo reference electrode and PtAu anode (synthesized as reported by Fu et al. , see Supplementary Information 1.3 for experimental details). The electrolyte was continuously flowed at 3 mL min -1 , N2 flowed to the cathode at 30 mL min -1 and H2 flowed to the anode at 30 mL min -1 . Current pulsing was employed, the standard pulses were 30 seconds at -6mA cm -2 geo, then 0 mA cm -2 geo for 120 seconds; changes in current density were matched with reduction in pulse parameters with the same multiplication factor. 80 Coulombs were passed during the current pulsing in all experiments. Detailed explanations of the experiments undertaken can be found in the Supplementary Information.