Derivative and Differential Voltammetry and Reciprocal Derivative Chronopotentiometry Identical Behavior Verification for Electrode Reversible Processes

Abstract

Voltammetric differential-pulse techniques are very useful electrochemical techniques for characterizing electrode processes. [1][2][3] The response obtained in these techniques can be considered as an approximation of the successive derivatives of the I vs. E curve, and it presents one or two peaks which are characteristic of the process analyzed. Thus, for example, differential pulse voltammetry (DPV) is a double-pulse technique whose response emulates the first derivative of the I vs. E curve, 1,4-8 while double differential pulse voltammetry (DDPV) is a recently designed triple-pulse technique whose response emulates the second derivative of the I vs. E curve. 9-11 The signals obtained in these differential and double differential pulse techniques coincide with the first and second derivative of the I vs. E curve, respectively, when the difference between the applied potential pulses, ⌬E, tends to zero.The true derivatives of the I vs. E curve are the responses corresponding to derivative voltammetry (DV), a potentiostatic technique which has received little attention in the literature due to the problems of the differentiation of digitally acquired signals, in particular the low signal-to-noise ratio. 12 However, modern digital filtering techniques can alleviate to a great extent the problems associated with the differentiation of the I vs. E signal, 13 and, therefore, we can use differential and double differential pulse voltammetry together with the derivative voltammetry technique in order to study electrode processes.Another derivative technique which has been much used in recent years for the study of different electrode processes is reciprocal derivative chronopotentiometry, 14-18 due to the fact that this technique, based on the plotting of the reciprocal of the time derivative of the chronopotentiogram vs. the measured potential (dt/dE vs. E), presents a characteristic peak that is quantitatively related to the kinetic and thermodynamic parameters of the electrode process and is scarcely affected by the capacitative effects on account of the fact that it has been obtained from the central zone of the E vs. t curve. This derivative technique is very simple to apply, and it presents high reproducibility in the measure of the peak potentials and peak heights, affording simple diagnosis criteria for the electrode processes analyzed. 17 In a recent paper we gave the conditions under which it is possible to establish a total analogy between the potentiostatic response when a constant potential E is applied and the chronopotentiometric response when a programmed current of the general form I(t) ϭ I 0 t u , u Ն Ϫ1/2 is applied, in the case of a reversible electrode process. 19 This analogy was extended to the potentiostatic technique DPV at the limit in which its response is analogous to that of derivative voltammetry technique (⌬E r 0), and to a new reciprocal derivative chronopotentiometric technique with programmed current proposed in the above mentioned paper which consists of the analysis of the dt uϩ1/...

Reciprocal Derivative Chronopotentiometry with Programmed Current: Influence of the Reversibility

“…We demonstrated that it is possible to establish a total analogy between both potentiostatic and chronopotentiometric responses [1,2].…”

“…In a previous article we compared the responses obtained in derivative and differential voltammetric techniques and those corresponding to reciprocal derivative chronopotentiometry with a programmed current of the form I(t) I 0 t u , with u > À1/2 (dt u1/2 /dE ÀE and d 2 t u1/2 /dE 2 ÀE responses) for reversible processes [1]. We demonstrated that it is possible to establish a total analogy between both potentiostatic and chronopotentiometric responses [1,2].…”

Study of Electrochemical Processes with Coupled Homogeneous Chemical Reaction in Differential Pulse Voltammetry at Spherical Electrodes and Microhemispheres

“…Derivative Voltammetry (DV): the response obtained in the DV technique corresponds to the first derivative of the single pulse I -E curve (dI/dE vs. E) [9,14]. Under dkss conditions the expression for DV curve is given by:…”

Study of the Behavior of an EC Mechanism Using Cyclic and Derivative Chronopotentiometric Techniques with Spherical Electrodes

“…In this section we will show the response corresponding to an EC mechanism in reciprocal derivative chronopotentiometry with constant current in its traditional form, i.e., by plotting the reciprocal of the time derivative of the chronopotentiogram versus the measured potential (dt/dE vs. E curve) [10, 16 ± 18] and also in the form proposed in recent articles, which consists of plotting the dt 1/2 /dE versus E curve [15,19]. The latter gives a practically identical signal to that obtained in differential pulse voltammetry when electrode processes with reversible charge transfer reactions are studied under planar diffusion conditions.…”

“…Moreover, this derivative technique is very simple to apply, and it presents high reproducibility in the measure of the peak potentials and peak heights, thus affording simple diagnosis criteria for the electrode process analyzed [15].…”