Linear Sweep Voltammetry


Introduction

Linear sweep voltammetry is a general term applied to any voltammetric method in which the potential applied to the working electrode is varied linearly in time. These methods would include polarography, cyclic voltammetry, and rotating disk voltammetry. The slope of this ramp has units of volts per unit time, and is generally called the scan rate of the experiment.

The value of the scan rate may be varied from as low as mV/sec (typical for polarography experiments) to as high as 1,000,000V/sec (attainable when ultramicroelectrodes are used as the working electrode). With a linear potential ramp, the faradaic current is found to increase at higher scan rates. This is due to the increased flux of electroactive material to the electrode at the higher scan rates The amount of increase in the faradaic current is found to scale with the square root of the scan rate. This seems to suggest that increasing the scan rate of a linear sweep voltammetric experiment could lead to increased analytical signal to noise. However, the capacitive contribution to the total measured current scales directly with the scan rate. As a result, the signal to noise of a linear sweep voltammetric experiment decreases with increasing scan rate.


Further Information


/chem-ed/echem/linsweep.htm, updated 10/29/96

Copyright © 1996 by Mark R. Anderson, all rights reserved.

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