for the O-upd rate of the overall O-upd reaction equation (Eq. 5d). The best fit is obtained for a formal potential of 𝐸 ∘≀ = 870 mVRHE and, for a characteristic charge of 𝑄 3 = 210 µC/cm 2 (can be chosen freely, here corresponding to one elementary charge per Pt surface atom), 𝑚 &'() = 66 cm 2 /mC and 𝑥 = 4.