As described above, the key products that form concomitantly during aCGDE are H 2 , O 2 and H 2 O 2 , whose electrocatalytic properties with Pt electrodes are well described in literature. In order to assess whether or not the features observed in Figs. and are related to the presence of these species in solution after aCGDE, we performed a separate set of cyclic voltammetry measurements in electrolytes saturated with either one of the reactants possibly formed during aCGDE, shown in Fig. . The grey curve shows the cyclic voltammogram (CV) of Pt recorded in N 2 saturated 0.01 M KOH, the light blue curve in O 2 saturated 0.01 M KOH, the pink curve in H 2 saturated 0.01 M KOH and the orange curve in 0.01 M KOH containing H 2 O 2 . Additional measurements with a larger upper potential limit are shown in Fig. . All CVs were recorded at a scan rate of 50 mV s -1 .