A formal scan rate in staircase and square-wave voltammetry

Because of the fact that real measurements are sometimes described in terms of the (formal) scan rate, the functional relationships between this parameter and the peak current in staircase (SCV) and square-wave voltammetry (SWV) were investigated theoretically. The real SCV peak current is proportional to the square-root of the formal scan rate, v, and inversely proportional to Delta E-0.0541: -i(p) = 0.1453nFSc(ox)(center dot)(D/pi)(1/2)nu(1/2)Delta E-0.0541. In SWV of a reversible electrode reaction the net peak current depends primarily on the frequency, while the influence of the formal scan rate is of minor importance: Delta i(p) = nFSc(ox)(center dot) D-1/2(0.7339f1/2 + 0.0026 Delta E0.3118 nu(1/2)). On the other hand, in SWV of a totally irreversible electrode reaction, the real net peak current is a stronger function of the formal scan rate: Delta i(p) = 0.0942nFSc(ox)(center dot)D(1/2)Delta E-0.11 nu(1/2). Experimental results, obtained in perchlorate solutions of Eu3+, are in relatively good agreement with the theory. (C) 2010 Elsevier B.V. All rights reserved.