which is the final reduction step and always generates current. Below the equilibrium potential of R8, R6 would be followed by OH* desorption. Above this potential, OH* desorption is stopped as OH* becomes more stable than OH -. It also affects O* reduction even when it goes through R7, as the product OH -near the electrode surface should be followed by OH -adsorption. The sum of R7 and the reverse R8 is equivalent to R6, and no net reduction current would be produced. In other words, above the equilibrium potential of R8, the ORR current shall be stopped.