Chapter 3 Linear Sweep and Cyclic Voltammetry

Abstract

This chapter focuses on linear sweep and cyclic voltammetry. Polarography refers to measurements at the dropping mercury electrode while measurements at stationary electrodes are referred to as linear sweep voltammetry (LSV). This chapter discusses measurements at stationary electrodes and illustrates typical experimental apparatus for conducting LSV or cyclic voltammetry (CV). The cell shown is the simplest version and contains the electrolyte in a single compartment into which all three electrodes are inserted. The electrolytic current (I) flows through the electrolyte between the working (W) and counter (C) electrodes. The electrode potential of interest (E) is that between W and the reference electrode (R). The LSV current–voltage curve, often called an LSV wave, for a reversible charge-transfer reaction is presented. The theoretical treatment of mass transfer in LSV and CV assumes that only diffusion is operative. The chapter also discusses the theoretical LSV and CV response in terms of the Faradaic current––that is, the current arising from an electrode reaction––and has referred to the electrode potential as the potential difference between the working and reference electrodes. Because the reactions of electrode-generated intermediates frequently involve sequential steps, either heterogeneous or homogeneous, it is convenient to use a short-hand notation to describe the processes. Quantitative studies using LSV and CV can be carried out for both heterogeneous charge-transfer kinetics and the kinetics of homogeneous chemical reactions coupled to charge transfer at electrodes.