Characterizing electrode reactions by multisampling the current in square-wave voltammetry

Abstract

A B S T R A C TA novel and simple methodology for characterization of electrode processes by square-wave voltammetry (SWV), considered as a complex repetitive double-step chronoamperometric experiment, is proposed. Specifically, the sampling of the current at the very end of each potential pulse, as common in conventional SWV, is replaced with a multisampling protocol during each potential pulse, resulting in generation of a series of corresponding multisampled SW voltammograms constructed out of a single measurement. The evolution of such voltammograms reflects the chronoamperometric properties of the current in the course of each potential pulse, thus being specific to electrode mechanism and electrode kinetics. The proposed methodology could serve as a basis for modification of common SWV mode in commercially available instrumentation for the purpose of an advanced characterization of electrode processes. The methodology is theoretically illustrated by the analysis of three kinetically controlled common electrode mechanisms, such as the electrode reaction of a solution resident and surface confined redox couples, as well as the regenerative catalytic electrode mechanism (EC'), while the experimental verification is done with the electrode reaction of Eu 3+ /Eu 2+ and azobenzene/ hydrazobenzene redox couples.

Electrochemical Faradaic Spectroscopy

“…Let us recall that such behaviour was not observed in conventional SWV of the studied electrode reaction (curve ( g ) in Figure A). The quasireversible maximum in conventional SWV is a characteristic of surface confined electrode processes, or complex electrode mechanisms complicated by either reactant, or both reactant and electrode reaction product adsorption .…”

“…The proposed methodology is tested by theoretical analysis of the response of a simple, kinetically controlled electrode reaction at a planar macroscopic electrode of a solution resident redox couple, where both forms are chemically stable species. For correlation with experimental data, the electrode reaction of the redox couple Eu 3+ (aq)/Eu 2+ (aq) at the hanging mercury drop electrode is considered …”

Theoretical Aspects of a Surface Electrode Reaction Coupled with Preceding and Regenerative Chemical Steps: Square‐wave Voltammetry of a Surface CEC’ Mechanism

“…Indeed, recognizing the nature of particular electrode mechanism is a crucial step in order to apply defined methodologies for the determination of relevant kinetics and thermodynamics parameters. In the last 3 decades, our group and others provided valuable theoretical methodologies in SWV to deal with these problems, even for very complex electrochemical mechanisms. In this work, we focus on specific surface electrochemical reaction, in which both electroactive participants, which are firmly immobilized at the surface of working electrode, are involved in different type of chemical reactions.…”

Protein‐film Voltammetry of Two‐step Electrode Enzymatic Reactions Coupled with an Irreversible Chemical Reaction of a Final Product – A Theoretical Study in Square‐wave Voltammetry

“…Therefore, the phenomena shown in Figure 4 can serve as another criterion for recognizing a surface EECirr mechanism with fast electrode steps, in case of SWV peaks-separation for at least of À 150 mV at potential scale between the second and the first SW peak. At this point, it is worth to point out that if second electrode step of surface EECirr mechanism occurs at potentials that are at least À 150 mV (or even more negative) than that of first electrode step, then we can apply successfully the methods elaborated in [23,[34][35][36][37][38][39][40][41][42] and in [33] to get independent access to kinetics of both electron transfer steps, as well as to the rate of the chemical step.…”