EC methods

Pulse Voltammetry

While in the standard cyclic voltammetry the potential is changed in a linear or a staircase form, in the pulse voltammetry methods the potential is modulated by an additional periodic square-wave signal (pulse) added to the electrode. The current is then measured at some points at the start and the end of each pulse, and then the difference of the currents is plotted as a function of the applied voltage. As a result, the response of the pulse voltammetry measurement is peaks (rather than waves as in standard CV) with the maxima at the redox potentials. The serious advantage of the pulse voltammetry methods is that the major component of the difference current is faradaic current while the background (charging) currents are mostly eliminated, which drastically improves the sensitivity of the method. Nowadays, two pulse voltammetry techniques are widely use, namely differential pulse voltammetry (DPV) and square-wave voltammetry (SWV). The response of both methods is similar, but they are different in the details of the applied pulses. In DPV, square pulse of the fixed size is added to the slowly changing potential ramp, and the measured current is the difference of currents before an application of the pulse and at the end of the pulse. In SWV, symmetrical square-wave pulse is added to the staircase potential ramp (one pulse at each staircase period), and the measured current is the difference between the forward and reverse currents.