Cells and Absolute Electrode Potentials

Knowledge of the Volta potential of a metal/solution interface is relevant to the interpretation of the absolute electrode potential. According to the modem view, the relative electrode potential (i.e., the emf of a galvanic cell) measures the value of the energy of the electrons at the Fermi level of the given metal electrode relative to the metal of the reference electrode. On the other hand, considered separately, the absolute value of the electrode potential measures the work done in transferring an electron from a metal surrounded by a macroscopic layer of solution to a point in a vacuum outside the solotion.  

Therefore the absolute potential of a single electrode is its electron work function (Fig. S), which may be expressed in the form 

It is clear that the Galvani potential, A (p, which is an electrostatic quantity, cannot be identified with the thermodynamic term called the electrode potential. 

The absolute electrode may be expressed also in terms of thermodynamic quantities describing the electrode reaction by means of the Bom- 

Haber-Fajans cycle, e.g., for the standard hydrogen electrode in the 

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