1. Method Overview
Square Wave Voltammetry (SWV) is a potentiostatic method that offers some advantages to common techniques like Cyclic Voltammetry (CV), in that the waveform is a series of pulses increasing along a linear baseline, where current is measured in a forward pulse and reverse pulse. The result is the current difference between forward and reverse pulses. The way in which the current is measured at each pulse aids in minimizing the measurement of background (charging) current. Related pulse-type methods include Normal Pulse Voltammetry (NPV) and Differential Pulse Voltammetry (DPV).
Square wave voltammetry (SWV) combines the aspects of several pulse voltammetric methods, including the background suppression and sensitivity of Differential Pulse Voltammetry (DPV), the diagnostic value of Normal Pulse Voltammetry (NPV), and the ability to interrogate products directly in the manner of Reverse NPV.
In an SWV experiment, the potential of the working electrode is stepped through a series of forward and reverse pulses from an initial potential to a final potential. The forward step is determined by the square amplitude and the reverse step is determined by subtracting the square increment from the square amplitude. Cyclic Square Wave Voltammetry (CSWV) is a variant where the potential of the working electrode is cycled between an Upper potential and a Lower potential.
In the simplest case, when Segments (SN) = 1 (see Figure below), potential pulses in a forward and reverse pulse, along a linearly increasing baseline from an initial to final potential, sampling current at specified intervals (see Figure below).
During each forward or reverse pulse, current is sampled at the same period within the pulse duration as set by entering Sampling width (TSW, W) into the Basic tab (see below). The period of a pulse (TSW, P) includes both forward and reverse pulses; thus, the current sampled in the forward pulse is at,
and the current is sampled in the reverse pulse at,
as shown in the Figure below.