Fundamental Principles of Organic Electrochemistry: Fundamental Aspects of Electrochemistry Dealing with Organic Molecules - Fundamentals and Applications of Organic Electrochemistry - page 9

Although the reference electrodes introduced in
this section are commercially available, they
can also be made in the laboratory.
2.3 Auxiliary Electrodes
The auxiliary electrode, often also called the
counter electrode, is an electrode used in a
three-electrode electrochemical cell for
voltammetry in which the electrical current
passes between the working and auxiliary
electrodes. The auxiliary electrode therefore
functions as a cathode whenever the working
electrode is operating as an anode and vice
versa. The auxiliary electrode often has a
surface area much larger than that of the
working electrode to ensure that the
half-reaction occurring at the auxiliary
electrode can occur fast enough so as not to
limit the process at the working electrode [4].
Platinum (e.g. Pt wire, Pt plate) is a good
material for the auxiliary electrode due to its
high stability.
2.4 Solvents and Supporting
Electrolytes
The important factors for solvents in
voltammetry are the potential window, the
solubility of the substrate molecule under study
and physical-chemical properties such as donor
or solvating properties [5]. Although water is