Reference Electrodes

In experimental electrochemistry, it is common to use a reference electrodes when controlling current or voltage with a potentiostat. Potential differences in the system are recorded with respect to the equilibrium potential of the redox couple at the reference electrode. A good reference electrode is designed so that no net charge transfer takes place at its electrode-electrolyte interface. Then the overpotential of the reference is zero, so:

(3-15)

where

s , ref (SI unit: V) is the electric potential of the reference electrode and Eeq, ref (SI unit: V) is the equilibrium potential of the reference electrode reaction.

The electric potentials of the electrodes in the electrochemical cell can then be defined with respect to the reference electrode according to:

(3-16)

Where Evs ref (SI unit: V) is the electrode potential versus the defined the electric reference potential.

It is important to realize that the presence of an ideal reference electrode in the system has no impact on the physics; the only purpose of the reference electrode is to define a stable reference point for the potential levels.