Once the COOR rate has decreased to zero, we now observe a distinct reduction peak C1 in the COOR-CVs (instead of a reduction region observed for lower UPLs, see above), which must be related to the electrochemical removal of OH/O species by reduction to water. This peak increases with increasing UPL for the Pt-1 electrode, while for the Pt-3 electrode, it seems to decrease (see insets and Fig. ). For the Pt-3 electrode, we suggest that this apparent decrease of the peak C1 (and shift to lower potential) is caused by an increasing overlap between the steeply declining COOR current and the peak C1 reduction peak. For the Pt-1 electrode, the reduction peak is located at more negative potentials than the declining COOR curves. Here, the increase in peak C1 can be rationalized by increasing amounts of OH/O species formed on the exposed Ru(0001) substrate. In the redox-CV in Figs. and, the reduction peak for OH/O removal (see inset) has a similar size for both electrodes and seems to be mostly independent from the applied UPL. The shape varies slightly, and the peak maximum is at slightly different potentials. In principle, if our suggestion from above is correct, that the amount of OH increases at higher UPLs, then the charge within that peak should increase. Such information can, however, not be confirmed from the present data.