Figure shows that when C2O4 2-is directly oxidized, a maximum CO2 •-concentration of 0.32 µM is obtained ~ 150 nm from the electrode surface. In contrast, DiMeFc + -mediated C2O4 oxidation results in a maximum CO2 •-concentration of 0.60 µM at a distance of 20 µm from the electrode surface (Figure , dashed line), over two orders of magnitude further from the electrode surface compared to direct C2O4 2-oxidation. These simulations are consistent with the use of a mediator to form CO2 •-away from the electrode surface such that it can be used as a single electron reductant for homogeneous reductions in solution.