Previous GCE-DFT studies in electrochemistry have almost exclusively focused on innersphere reactions while the important class of outer-sphere reactions, where the interactions between the electrode and the redox species are weak, has gained less attention and is therefore only partially understood. Most theoretical models of outer-sphere electron transfer assume that outer-sphere couples do not hybridize with the electrode so that the total system can be considered as a weakly interacting combination of electrode and solvent-phase subsystems. As the electrode and redox couple belong to distinct phases, it should be possible to individually control their properties and to modulate the electrode potential independent of the solution phase as schematically shown in Figure . As long as the electrode Fermi level is above the Ru[NH 3 ] 3+ 6 reduction potential (≤-4.6 V), the electrode determines E DF T f . However, when the Fermi level falls below the reduction potential, E DF T f nominally resides on the solution-phase Ru[NH 3 ] 3+