Auxiliary electrode Auxiliary electrode The auxiliary electrode, often also called the counter electrode, is an electrode used in a three electrode electrochemical cell for voltammetric analysis or other reactions in which an electric current is expected to flow. The auxiliary electrode is distinct from the reference electrode, which establishes the electrical potential against which other potentials may be measured, and the working electrode, at which the cell reaction takes place. In a two-electrode system, either a known current or potential is applied between the working and auxiliary electrodes and the other variable may be measured. The auxiliary electrode functions as a cathode
Electrode potential that only the magnitude expressed according to the convention (2) be called "the electrode potential". To avoid possible ambiguities, the electrode potential thus defined can also be referred to as "Gibbs–Stockholm electrode potential". In both conventions, the standard hydrogen electrode is defined to have a potential of 0 V. Both conventions also agree on the sign of "E" for a half-cell reaction when it is written as a reduction. The main difference between the two conventions is that upon reversing the direction of a half-cell reaction "as written", according to convention (1) the sign of "E" also switches, whereas in