Diagnostic Criteria for the Characterization of Electrode Reactions with Chemical Reactions Following Electron Transfer by Cyclic Square Wave Voltammetry

Helfrick, John C.; Mann, Megan A.; Bottomley, Lawrence A.

doi:10.1016/j.electacta.2016.04.006

Cited by 12 publications

(16 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[9][10][11][12][13][14] In the following sections, we present the results of our simulations in a similar fashion, first considering the impact of the chemical reaction rate on the shape of the voltammogram and then individually examining the impact of the each empirical parameter. We conclude with a set of instructions on how to identify an electrode reaction as an ECE mechanism and determining k f from empirical data.…”

Section: Resultsmentioning

confidence: 99%

“…4 and is comparable to the trend for an EC mechanism. 13 Similarly, the ratio of + p,r2 / + p,f2 ranges between 1 and 2 depending upon log k f and period. At log k f ≤ 0, this ratio increases to a value of two and then decreases to a value of one.…”

Section: Resultsmentioning

confidence: 99%

“…Peak ratios deviate from unity and are indicative of both a following and preceding chemical reaction. 17 It is interesting to note that the trends for the first process mirror those for an EC mechanism; 13 however, the trends for the second process are unlike the trends for a CE mechanism. 12 Taken collectively, systematic variation of period provides a diagnostic trend characteristic of the ECE mechanism from which the magnitude of k f can be determined.…”

Section: Effect Of Period (τ)mentioning

confidence: 98%

“…12 Peak ratios for the first process are ≤1 (similar to an EC mechanism) and for the second process ≥1 (similar to a CE process). 12,13 Peak potential dependence on increment can provide a measure of k f if E 0 1 is known. When the two processes are not resolved along the potential axis, trends in peak potentials and peak current ratios distinguish this mechanism from a reversible, quasireversible, EC, and CE mechanism (vide supra).…”

Section: Effect Of Period (τ)mentioning

confidence: 99%

“…[9][10][11][12][13][14] In this work, we critically evaluate CSWV for the analysis of consecutive electron transfers coupled by a homogeneous irreversible chemical reaction, i.e. an ECE mechanism.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

Mann

Helfrick

Bottomley

2015

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

Theory for cyclic square wave voltammetry of an irreversible first-order chemical reaction coupling two electron transfers, i.e. an ECE mechanism, is presented. Theoretical voltammograms were calculated following systematic variation of empirical parameters to assess their impact on the shape of the voltammogram. Note that the results presented herein are applicable only to ECE processes where E 0 for the second electron transfer step is negative of that for the first. Under this condition, disproportionation reactions do not occur. From the trends obtained, diagnostic criteria for this mechanism were deduced. When properly applied, these criteria will enable non-experts in voltammetry to assign the electrode reaction mechanism and accurately measure reaction kinetics over the range −2 ≤ log k f ≤ 6. Square wave voltammetry (SWV) has been shown to be particularly useful in identifying electrode reaction mechanisms especially those involving chemical reactions coupled to the electron transfer step.1-7 Although a strong theoretical basis exists, 8 the use of SWV for identifying electrode reaction mechanisms has been limited to a small number of electrochemists. Our goal is to broaden the use of SWV for determining electrode reaction mechanisms especially by nonexperts in electrochemistry who make occasional use of voltammetry in characterizing new compounds. Cyclic square wave voltammetry (CSWV) is a modified form of SWV that steps through the region of the formal potential of the electroactive species under study and back to the initial potential as shown in Fig. 1a. The empirical parameters that comprise the CSWV waveform are period (τ), amplitude (E sw ), increment (δE), and the potential at which the direction of the sweep is reversed (E λ ).Our current effort is focused on identifying the specific mechanisms CSWV provides a straightforward means for determining the mechanism and associated kinetic parameters. [9][10][11][12][13][14] In this work, we critically evaluate CSWV for the analysis of consecutive electron transfers coupled by a homogeneous irreversible chemical reaction, i.e. an ECE mechanism. The process used to evaluate CSWV is as follows. Theoretical voltammograms were computed by systematic variation of each empirical parameter. Figures of merit that describe the shape of the voltammogram as shown in Fig. 1b (peak potentials, peak currents, and peak widths) were compiled and correlated with the empirical parameter being varied. Trends characteristic of this mechanism were identified from these correlations and provide diagnostic criteria for assigning an electrode reaction as an ECE process. Application of these criteria will enable non-specialists to accurately assign the mechanism and, in many instances, quantify the rate constant of the chemical reaction.The ECE mechanism has been the subject of considerable interest by electrochemists over the past five decades. [2][3][4][15][16][17][18][19][20][21][22][23][24] The continuing interest reflects: (1) the challenge in mathematically modeling the...

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Effect Of Period (τ)mentioning

confidence: 98%

Section: Effect Of Period (τ)mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

Mann

Helfrick

Bottomley

2015

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

show abstract

Diagnostic Criteria for the Characterization of Electrode Reactions with Chemically Coupled Reactions Preceding the Electron Transfer by Cyclic Square Wave Voltammetry

2016

Self Cite

View full text Add to dashboard Cite

Theory for cyclic square wave voltammetry of electrode reactions with chemical reactions preceding the electron transfer is presented. Theoretical voltammograms were calculated following systematic variation of empirical parameters to assess their impact on the shape of the voltammogram. From the trends obtained, diagnostic criteria for this mechanism were deduced. When properly applied, these criteria will enable non-experts in voltammetry to assign the electrode reaction mechanism and accurately measure reaction kinetics.

show abstract

Square-wave protein-film voltammetry: new insights in the enzymatic electrode processes coupled with chemical reactions

Gulaboski

Mirčeski

Lovrić³

2019

J Solid State Electrochem

View full text Add to dashboard Cite

Redox mechanisms in which the redox transformation is coupled to other chemical reactions are of significant interest since they are regarded as relevant models for many physiological systems. Protein-film voltammetry, based on surface confined electrochemical processes, is a methodology of exceptional importance, which is designed to provide information on enzyme redox chemistry. In this work, we address some theoretical aspects of surface confined electrode mechanisms under conditions of square-wave voltammetry (SWV). Attention is paid to a collection of specific voltammetric features of a surface electrode reaction coupled with a follow-up (EC rev), preceding (C rev E) and regenerative (EC') chemical reaction. While presenting a collection of numerically calculated square-wave voltammograms, several intriguing and simple features enabling kinetic characterization of studied mechanisms in time-independent experiments (i.e., voltammetric experiments at a constant scan rate) are addressed. The aim of the work is to help in designing a suitable experimental setup for studying surface electrode processes, as well as to provide a means for determination of kinetic and/or thermodynamic parameters of both electrode and chemical steps.

show abstract

Diagnostic Criteria for the Characterization of Electrode Reactions with Chemical Reactions Following Electron Transfer by Cyclic Square Wave Voltammetry

Cited by 12 publications

References 32 publications

Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

Diagnostic Criteria for the Characterization of Electrode Reactions with Chemically Coupled Reactions Preceding the Electron Transfer by Cyclic Square Wave Voltammetry

Square-wave protein-film voltammetry: new insights in the enzymatic electrode processes coupled with chemical reactions

Contact Info

Product

Resources

About