Three-electrode cells comprise (1) an indicator (or test) electrode or a
working electrode, at the surface of which processes that are of interest may occur, (2) a
reference electrode and (3) a third electrode, the auxiliary or counter electrode, which serves merely
to carry the current flowing through the cell, and at the surface of which no processes
of interest occur. If processes of interest occur at both the
anode and the
cathode of a cell (as in differential amperometry or controlled current potentiometric
titration with two indicator electrodes), the cell should be said to comprise two indicator
(or test) working electrodes.
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