Theory of differential pulse voltammetry at stationary planar electrodes

Abstract

Differential pulse voltammetry (DPV) at stationary solid electrodes has the characteristic that the current after any given potential step is affected by all the preceding steps since the beginning of an entire sequence of potential, changes applies to one and the same electrode. The equation for the DPV wave is derived and is calculated numerically for the reversible, the totally irreversible and the quasi-reversible cases. The DPV waves thus obtained are expressed by five parameters, two of which are kinetic parameters, i.e. the electrode reaction rate constant and transfer coefficient, and three of which are concerned with the potential-time waveform, given by r =ρ/δ, w=(nFv/RT) δ and Δζ= nF Δ E/RT , where τ is the interval between two successive pulses, δ the pulse duration, Δ E the pulse height and v the potential sweep rate. The peak current and peak potential are obtained for various combinations of these parameters. As a result, criteria for reversible, quasi-reversible and totally irreversible waves are described. For convenience in the quantitative analysis of DPV waves, approximate equations for the peak current and the peak potential are obtained as functions of these parameters.