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# Linear Sweep Voltammetry: Introduction and Applications

Linear sweep voltammetry (LSV) is a simple electrochemical technique. The method is similar to cyclic voltammetry, but rather than linearly cycling over the potential range in both directions, linear sweep voltammetry involves only a single linear sweep from the lower potential limit to the upper potential limit.

Like cyclic voltammetry, linear sweep voltammetry uses a three electrode system. This consists of a working electrode, counter electrode, and reference electrode. The electrodes are placed in an electrochemical cell, which contains the solution of interest, and are connected to a potentiostat. The potentiostat controls the potential between the working and reference electrodes and measures the current at the working electrode so that a plot can be made that shows the electrochemical response (oxidation or reduction) of the material in question.

## Applications

Using linear sweep voltammetry, several key parameters can be observed which can be used diagnostically to determine thermodynamic reversibility of a material. These parameters include the peak current (ip), the potential at the peak current (Ep), and the potential at half the peak current (Ep/2) prior to the peak being reached.

These will be interpreted here for the system O + e- ⇌ R, with R initially absent (i.e. assuming no coupled reactions). These values can be used to calculate key electrochemical parameters at the reversible and quasireversible limits.

### The peak current

The peak current in amperes, ip, at 25 °C with bulk concentration O CO* in mol cm-3, electrode area A in cm2, the diffusion constant DO in cm2 s-1, and the scan rate v in V s-1 is given by:

For a reversible system K is 1, and for an irreversible system:

Graphs exist1, 2 to relate determine the degree of reversibility if α  is known.

### The peak current potential

The peak current is given by:

In the reversible system Ξ = 1.109 where as in the irreversible system:

Graphs exist1,2 to relate determine the degree of reversibility if α  is known.

### The half-peak current potential

The half peak current potential is given by the following formula:

For a reversible system ∆ = 2.20 , whereas for irreversible system:

Graphs exist1,2 to relate determine the degree of reversibility if α  is known.