Peak Current (ip)
The peak current is the (baseline corrected) current at the maximum (or minimum) of a feature in a CV. If the baseline current before the wave is 2 µA, then 2 µA must be subtracted from ip of wave under study. Non-zero baseline currents are to be expected, as it results from the act of changing the electrode potential, but it may also be due to the presence of another wave that occurs at an earlier time in the scan.
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It may be confusing that peak of the wave, where the maximum amount of electrons are passed, occurs at a potential just past the E1/2. This phenomenon is due to the diffusion of the analyte and not than the thermodynamics of the electron transfer, and will be fully explained in the Transport of Molecules in Solution section, but it underlines the need to describe features in a CV with E1/2 and not their Ep’s. The change in ip with scan rate can determine whether the electron transfer occurs between the electrode and a species in solution, or a species adsorbed on the electrode surface. The ip can also be used to measure the diffusion coefficient of an analyte with a simple equation that is covered in another section.
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