For the Pt-1 electrode, recording CVs with an UPL higher than 1.05 V leads to a shift of the onset potential for the COOR to lower potentials, apparent in a pre-peak or shoulder A2 in the CV (Fig. and Fig. ). It appears for UPLs larger than 1.1 V. The assignment of this peak / shoulder A2 to an ear-lier onset of the COOR is confirmed by an increase in the CO 2 current in the MS-CV in (Fig. ). The extent of the current increase depends on the number of potential cy-cles at a given UPL and the applied UPL (see Figs. and). A similar phenomenon has been reported previously and has been attributed to a potential induced restructuring of the electrode surface, which is also supported by the STM image in Fig. , recorded after the electrochemical measurements. It was suggested that newly formed low-coordinated sites on the restructured electrode enhance the COOR. Apparently, continuing surface restructuring of the Pt-1 electrode reduces the formation of OH/O species on the Pt-1 surface in the peak A1, leading to a decrease in size of that peak. On the other hand, this restructuring also leads to an enhanced COOR activity in the region of peak A2. During restructuring, the newly formed sites with lower coordination will bind OH/O stronger than sites on the flat Pt layers, thus allowing OH/O formation on the surface already at lower potentials. Hence, this also leads to the peak A2 in the redox-CV in Fig. (see inset), indicating OH/O adsorption in this potential region. Consequently, the restructuring reduces the number of sites on the flat Pt areas, leading to a decrease of Peak A1 in the redox-CV. This is also evident for the Pt-2 electrode described in Section S5, where with an increasing number of potential cycles (with increasing UPL -Fig. or fixed UPL -Fig. ), the COOR activity in the peak A1 decreases even further. Finally, the current density decreases in the entire potential region where the Pt-2 electrode is active for the COOR. STM images recorded after the COOR for the fully restructured electrode indicate that the Pt film formed large agglomerates on the surface, exposing the severely restricted Ru(0001) surface.