In brief, these CVs can be interpreted as follows. The CV recorded in N 2 saturated 0.01 M KOH (grey curve) shows the onset of HER at E < 0.05 V RHE , features for the ad-/desorption of hydrogen between 0.05 V RHE and 0.5 V RHE (which are sensitive to changes in surface crystallographic orientation), and the ad-/desorption of hydroxyl or oxide formation/reduction at E > 0.8 V RHE . The slightly negative current densities for E < ca. 0.95 V in this grey curve are caused by the reduction of residual O 2 in the electrolyte (ORR). Similar CVs to the grey curve are also obtained for all electrodes investigated before aCGDE in step A shown in Fig. .