Linear sweep voltammetry

Linear potential sweep

Linear sweep voltammetry is a voltammetric method where the current at a working electrode is measured while the potential between the working electrode and a reference electrode is swept linearly in time. Oxidation or reduction of species is registered as a peak or trough in the current signal at the potential at which the species begins to be oxidized or reduced.

Experimental method

The experimental setup for linear sweep voltammetry utilizes a potentiostat and a three-electrode setup to deliver a potential to a solution and monitor its change in current. The three-electrode setup consists of a working electrode, an auxiliary electrode, and a reference electrode. The potentiostat delivers the potentials through the three-electrode setup. A potential, E, is delivered through the working electrode. The slope of the potential vs. time graph is called the scan rate and can range from mV/sec to 1,000,000 V/sec . At higher scan rates the current is found to increase which improves the signal to noise ratio. Therefore higher scan rates lead to better signal to noise ratios.

The working electrode is where the oxidation/reduction reactions occur. The equation below gives an example of an oxidation occurring at the surface of the working electrode. ES is the standard reduction potential of A. As E approaches ES the current on the surface increases and when E=ES then the concentration of [A] = [A-] at the surface . As the molecules on the surface of the working electrode or oxidized/reduced they move away from the surface and new molecules come into contact with the surface of the working electrode. This flow of molecules to and from the working electrode causes the current.

See also

• Cyclic voltammetry
• Electroanalytical Methods

References

• Bard, Allen J.; Larry R. Faulkner (2000-12-18). Electrochemical Methods: Fundamentals and Applications (2 ed.) Page 226-227. Wiley. ISBN 0-471-04372-9.