Reverse Differential Pulse Voltammetry and Polarography

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1984

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 = ~'/8, w = (nFo/RT)8 and A~" = nFAE/RT, where ~-is the interval between two successive pulses, 8 the pulse duration, AE the pulse height and o 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.

Journal of Physical Chemistry C, 2022

A theoretical analysis of reversible and quasireversible electrode reactions of a dissolved redox couple under conditions of the novel technique of differential square-wave voltammetry (DSWV) is presented. The technique is recently introduced as a hybrid form between differential pulse voltammetry (DPV) and square-wave voltammetry (SWV) as the two most advanced and competitive pulse-form voltammetric techniques for a purpose of unifying their advantages and further advancing both techniques in terms of analytical performances, mechanistic analysis, and electrode kinetics. The potential modulation of DSWV consists of potential steps and pulses providing a plethora of voltammetric curves, which enable in-depth characterization of the electrode reaction with a minimal set of measurements. Based on numerical simulations, a set of criteria for characterization and differentiation between reversible and quasireversible electrode reactions are established.

Journal of Electroanalytical Chemistry, 2011

Simulated voltammograms obtained by employing Butler-Volmer (BV) and Marcus-Hush (MH) models to describe the electrode kinetics are compared for commonly used potential pulse techniques: chronoamperometry, Normal Pulse Voltammetry, Differential Multi Pulse Voltammetry, Square Wave Voltammetry and Reverse Pulse Voltammetry. A comparison between both approaches is made as a function of the heterogeneous rate constant, the electrode size, the applied potential and the electrochemical method, establishing the conditions in which possible differences might be observed. The effect of these differences in the extraction of kinetic parameters, diffusion coefficients and electrode radii are examined, and criteria are given to detect possible deviations of the experimental system from Butler-Volmer kinetics from the behaviour of the chronoamperometric limiting current. The Butler-Volmer model predicts the appearance of an anodic peak in Reverse Pulse Voltammetry for irreversible processes and a peak split of differential pulse voltammograms for quasireversible processes with a value of the transfer coefficient very different from 0.5 (smaller than 0.3 for a reduction process). These striking phenomena are studied by using the Marcus-Hush approach, which also predicts the anodic peak for slow electrode reactions in Reverse Pulse Voltammetry but not the split of the curve in differential pulse techniques.

Analytical Chemistry, 1994

Unlike single potential step techniques for which procedures to determine the rate constants of an irreversible electrode reaction are well documented, methods to obtain these rate constants by using potential step techniques barely have been described in the literature. In this paper, it has been shown that simple procedures to determine the values of the rate constants for electrode processes with a slow charge-transfer reaction by using double potential step chronoamperometry at plane electrodes can also be applied. In addition, these procedures provide criteria to assess easily the reversibility of the electrode reaction. Detailed methods of data analysis are also discussed.

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1987

A method is proposed for determining kinetic parameters from normal pulse polarographic data. This method is based on solving a set of simultaneous equations derived from the general current-potential relation originally given by Matsuda. The evaluation of the rate constant and transfer coefficient is simple and rapid and depends only upon the knowledge of such parameters as E

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1988

It is well knowu that the use of static mercury electrodes in normal pulse polarography (NPP) allows the capacitive current to be eliminated completely. Here it is shown that upon integrating the current following the polarizing pulse immediately after the capacitive contribution has faded out (which requires a time t _ = 3-5 ms in aqueous solutions) up to the end of the pulse, the signal to noise ratio is increased by 1-2 orders of magnitude with respect to conventional NPP at a static electrode. This depresses the detection limit of electroactive substances exchanging two electrons per molecule to 2 x Ws &4, and allows a s~~~tfo~~d kinetic study of sparingly soluble electroactive substances. In the case of irreversible electrode processes involving specifically adsorbed reactants and/or products, integration of the current from the very instant of the application of the polarizing pulse up to a time t,, after the end of the pulse, so as to include the capacitive contribution due to the backward potential jump, yields NP polarograms free of maxima as well as of the capacitive current. These polarograms exhibit a diffusion controlled limiting current and a rising portion which can provide valuable mechanistic information on the basis of a straightforward kinetic analysis. An application to the kinetic study of progesterone electroreduction on Hg from neutral aqueous media over the inflation range from lO_' to lo-' M is provided.

Electrochemistry Communications, 2005

An explicit approximate expression for half-wave potentials of irreversible steady-state current-voltage curves at a microdisk electrode was derived from the diffusion equation and the Butler-Volmer equation on the basis of the previous analytical method (J. E. C., 235 (1987) 87). The plot of the half-wave potential, E 1/2 , against ln(1-exp(-(E 1/2-E o))F/RT)] showed a linear relation with the slope of RT/αF, irrespective of the values of the kinetic parameters, where a is the radius of the electrode and α is the transfer coefficient. Values on the both axis in this plot are readily accessible from the voltammograms. The intercept gave the rate constant. Values of kinetic parameters obtained from the disk model were very close to those from the hemisphere model although there is big difference in current distribution on the two model electrodes.

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1988

Equations for a slow charge transfer reaction in normal pulse polarography (NPP), reverse pulse polarography (RPP), differential normal pulse polarography (DNPP) and differential pulse polarography (DPP), which take into account the cases where the reduction product dissolves both in the electrolyte solution and in the electrode, have been derived in a rigorous way. These equations have been obtained by adopting the expanding sphere electrode model for the DME because amalgam formation is associated with the sphericity of the electrode. Characteristics of the current-potential curves with and without amalgam formation are shown.

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1980

The theory is presented of a modified form of differential pulse voltammetry, in which two potential steps with similar short duration are superimposed on the rest potential. Expressions for the current response to the double potential step are derived for quasireversible and totally irreversible charge-transfer processes of simple electrode reactions at stationary electrodes. Some approximate equations are given for i-E curves, peak currents, peak half-widths, peak potentials and potentials at zero current.

Journal of …, 2009