Figure 12: (a) Schematic view of the experimental setup for the determination of quasi-Fermi level for electrons using the method of Roy. A 60 mL solution of KNO3 (0.1 M) with a small amount of M V 2 + is bubbled through with nitrogen in order to avoid the reoxidation of M V + by dissolved oxygen. (b) Structure of M V 2 + . (c) Determination of the value of pH0 from a typical potential versus pH curve.