𝑂𝑂𝐻 * stopped, and the counter electrode is disconnected, preventing any net electron transfer over the surface, and the open circuit potential (OCP) is recorded (Fig. ). One observes that the OCP increases sharply towards a constant value. The magnitude of this OCP rise increases both with O2 concentration and rotation rate. If one now reconnects the counter electrode and immediately records a CV in the cathodic direction, one will observe a reduction peak whose area increases with higher final OCP values. From the partial pressure and rotation rate dependency, the latter becoming relevant presently, one can reasonably conclude that the charge associated with this reduction peak stems from a process with molecular oxygen as a reactant. A charge-potential relationship is obtained by quantifying the charge of the reduction peak, stemming either from water oxidation or from molecular oxygen (Fig. ). This relationship is identical for both processes within measurement uncertainty (Fig. , f), thus suggesting that the associated redox reaction and, consequently, the oxygen species formed in both processes are the same.