Voltammograms: Overview

 A voltammogram is a graph generated experimentally, plotting current on the y-axis and applied potential on the x-axis.

Their shape depends on the method of measuring the current and the presence or absence of convection, which is the heat transfer by the macroscopic movement of a fluid.

In the presence of convection, the plot shows a sigmoid growth from the residual to the limiting current at a potential equal to the oxidation or reduction potential of the analyte.

Here, the limiting current suggests a constant value for the diffusion layer thickness, achieved by stirring the solution as observed in hydrodynamic voltammetry.

Without convection, the diffusion layer thickness is enhanced with time, leading to a peak current.

When the change in current is monitored against the potential, the peak current characterizes the plot.

The limiting current can be used to estimate the analyte concentration in the bulk solution, as it is directly proportional to the analyte concentration.

In addition, peak potentials determined from voltammograms can be applied to determine the standard state potentials of redox reactions by using the Nernst equation.