Copper-copper(II) sulfate electrode

The Copper-copper(II) sulfate electrode is a type of reference electrode, based on the redox reaction with participation of the metal (copper) and its salt - copper(II) sulfate. It is used for measuring electrochemical potential and is the most commonly used reference electrode for testing cathodic protection corrosion control systems.

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The corresponding equation can be presented as follow:

Cu²⁺ + 2e^- → Cu⁰(metal)

This reaction characterized by fast electrode kinetics, meaning that a sufficiently high current can be passed through the electrode with the 100% efficiency of the redox reaction (dissolution of the metal or cathodic deposition of the copper-ions).

The Nernst equation below shows the dependence of the potential of the copper-copper(II) sulfate electrode on the activity or concentration copper-ions:

$E=0.337 + \frac{RT}{2F} ln a_{Cu^{2+}}$

Commercial reference electrodes consist of a plastic tube holding the copper rod and saturated solution of copper sulfate. A porous plug on one end allows contact with the copper sulfate electrolyte. The copper rod protrudes out the tube. A voltmeter negative lead is connected to the copper rod.

The potential of a copper copper sulfate electrode is +0.318 volt with respect to the standard hydrogen electrode.