Absolute and Conventional Electrode Potentials

The electrons at the Fermi level of the metal in a normal hydrogen electrode (NHE) have an exactly defined energy, Ereu relative to the energy of the free electron in vacuum. Taking a redox system as an example, then the absolute energy scale of a redox system is only shifted against the conventional scale by the free energy, Er d, i-e.. 

Because of these discrepancies, we also use Lohmann s value of Er t = - 4.50 for NHE, so that the electron energy of any redox system is given by 

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Fig. 12. Position of the band edges of various semiconductors in absolute and conventional electrode potential scale at pH = 7 GaP (40). CdSe (41), CdS (42), ZnO (43), T1O2 (44, 45), SnC>2 (46) and the electron transfer terms of the excited rhodaminc in solution...

Figure 4. Absolute and conventional electrode potential scale.

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