with U PZC the experimental PZC vs SHE (=0.5 V for Au(111) ) and constant C = 25 µF/cm 2 Helmholtz capacitance for simplicity. We choose to use the above relation also here (with ) in order to draw a connection between our simulations and experimentally relevant ORR potentials. We strongly emphasize though that our analysis through Eq. ( ) represents a constant-charge approximation to the formally correct (electronically) grand-canonical picture. This approximation ignores any adsorbate-induced changes to the workfunction. We emphasize therefore that the conversion between σ (as well as the modeled electric field ⃗ E underlying the dipole-field curves in Figure ) and measurable potential values must be considered with caution and only tentatively. Quantifying the extent of this error is subject of ongoing work. A second, important approximation that needs to be clearly pointed out is that we assume here the same U PZC for both the clean and OH*covered Pt(111) models. While this is obviously incorrect, the predicted independence of potential for key target properties (such as the O 2 * adsorption energy or oxidation state)