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Recent Advances in Voltammetry.

Batchelor-McAuley C, Kätelhön E, Barnes EO, Compton RG, Laborda E, Molina A - ChemistryOpen (2015)

Bottom Line: The transformation over the last decade of the level of modelling and simulation of experiments has realised major advances such that electrochemical techniques can be fully developed and applied to real chemical problems of distinct complexity.This review focuses on the topic areas of: multistep electrochemical processes, voltammetry in ionic liquids, the development and interpretation of theories of electron transfer (Butler-Volmer and Marcus-Hush), advances in voltammetric pulse techniques, stochastic random walk models of diffusion, the influence of migration under conditions of low support, voltammetry at rough and porous electrodes, and nanoparticle electrochemistry.The review of the latter field encompasses both the study of nanoparticle-modified electrodes, including stripping voltammetry and the new technique of 'nano-impacts'.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford South Parks Road, Oxford, OX1 3QZ, UK.

ABSTRACT
Recent progress in the theory and practice of voltammetry is surveyed and evaluated. The transformation over the last decade of the level of modelling and simulation of experiments has realised major advances such that electrochemical techniques can be fully developed and applied to real chemical problems of distinct complexity. This review focuses on the topic areas of: multistep electrochemical processes, voltammetry in ionic liquids, the development and interpretation of theories of electron transfer (Butler-Volmer and Marcus-Hush), advances in voltammetric pulse techniques, stochastic random walk models of diffusion, the influence of migration under conditions of low support, voltammetry at rough and porous electrodes, and nanoparticle electrochemistry. The review of the latter field encompasses both the study of nanoparticle-modified electrodes, including stripping voltammetry and the new technique of 'nano-impacts'.

No MeSH data available.


Related in: MedlinePlus

Flow diagram showing the proposed strategy for delineating kinetic and mass-transport effects allowing the detection of authentic nanoelectrocatalysis.
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fig27: Flow diagram showing the proposed strategy for delineating kinetic and mass-transport effects allowing the detection of authentic nanoelectrocatalysis.

Mentions: Figure 27 outlines a general strategy for the combined experimental and computation study of electrocatalytic processes at electrodes modified with ensembles of nanoparticles. This methodology allows the influence of the mass transport and the interfacial electron-transfer kinetics upon the voltammetry to be clearly delineated.157 Briefly, the approach requires characterisation of the electrode in terms of particle size, aggregation, and separation, allowing the voltammetric response to be simulated using the kinetic parameters obtained using a macroelectrode. From comparison of the simulated ‘bulk’ response and the experimentally recorded data, it is possible to determine if the kinetics have been altered while fully accounting for the diffusional mass transport of the material. From this analysis three outcomes are possible. If the nanoparticle array simulation using the ‘bulk’ kinetics is in good agreement with the experimentally recorded data for the nanoparticle array, then the conclusion must be that there is no evidence of a nano-effect associated with using the nanomaterial. Conversely, if the simulated voltammetric response differs from that found experimentally, then the kinetics of the electrochemical reaction must have been altered through the use of the nanomaterial. This alteration in the kinetics may lead to an increase in the overpotential required to drive the reaction; hence, for such situations, the nanomaterial is less catalytic than the bulk material, and one has evidenced a ‘negative’ nano-effect. Alternatively, if the overpotential required for the electrochemical reaction is decreased as compared to the simulated result then it can be confirmed that the use of the nanomaterial has led to an authentic nano-effect. This procedure was applied to the experimental study of arrays of gold nanoparticles ranging in size from 20 to 90 nm in diameter. From these experiments, it was confirmed that for nitrite electro-oxidation, no alteration in the kinetics is observed between the use of gold nanoparticles and a gold macroelectrode.157 Conversely, the electro-oxidation of l-ascorbate was shown to exhibit true nanocatalytic effects. The origins of these differences were ascribed as likely being due to the l-ascorbate oxidation involving adsorbed intermediates.157 Finally, this same methodology has been applied to the oxygen reduction reaction and the hydrogen evolution reaction, where for small gold nanoparticles (1.9 nm diameter), the electrochemical processes were found to be significantly hindered as compared to the kinetics recorded on the macroelectrode.158 This is a prime example of how decreasing the size of the nanoparticles has led to a ‘negative’ electrocatalytic effect, likely resulting from the changed reaction intermediate adsorption on the gold surface.


Recent Advances in Voltammetry.

Batchelor-McAuley C, Kätelhön E, Barnes EO, Compton RG, Laborda E, Molina A - ChemistryOpen (2015)

Flow diagram showing the proposed strategy for delineating kinetic and mass-transport effects allowing the detection of authentic nanoelectrocatalysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4522172&req=5

fig27: Flow diagram showing the proposed strategy for delineating kinetic and mass-transport effects allowing the detection of authentic nanoelectrocatalysis.
Mentions: Figure 27 outlines a general strategy for the combined experimental and computation study of electrocatalytic processes at electrodes modified with ensembles of nanoparticles. This methodology allows the influence of the mass transport and the interfacial electron-transfer kinetics upon the voltammetry to be clearly delineated.157 Briefly, the approach requires characterisation of the electrode in terms of particle size, aggregation, and separation, allowing the voltammetric response to be simulated using the kinetic parameters obtained using a macroelectrode. From comparison of the simulated ‘bulk’ response and the experimentally recorded data, it is possible to determine if the kinetics have been altered while fully accounting for the diffusional mass transport of the material. From this analysis three outcomes are possible. If the nanoparticle array simulation using the ‘bulk’ kinetics is in good agreement with the experimentally recorded data for the nanoparticle array, then the conclusion must be that there is no evidence of a nano-effect associated with using the nanomaterial. Conversely, if the simulated voltammetric response differs from that found experimentally, then the kinetics of the electrochemical reaction must have been altered through the use of the nanomaterial. This alteration in the kinetics may lead to an increase in the overpotential required to drive the reaction; hence, for such situations, the nanomaterial is less catalytic than the bulk material, and one has evidenced a ‘negative’ nano-effect. Alternatively, if the overpotential required for the electrochemical reaction is decreased as compared to the simulated result then it can be confirmed that the use of the nanomaterial has led to an authentic nano-effect. This procedure was applied to the experimental study of arrays of gold nanoparticles ranging in size from 20 to 90 nm in diameter. From these experiments, it was confirmed that for nitrite electro-oxidation, no alteration in the kinetics is observed between the use of gold nanoparticles and a gold macroelectrode.157 Conversely, the electro-oxidation of l-ascorbate was shown to exhibit true nanocatalytic effects. The origins of these differences were ascribed as likely being due to the l-ascorbate oxidation involving adsorbed intermediates.157 Finally, this same methodology has been applied to the oxygen reduction reaction and the hydrogen evolution reaction, where for small gold nanoparticles (1.9 nm diameter), the electrochemical processes were found to be significantly hindered as compared to the kinetics recorded on the macroelectrode.158 This is a prime example of how decreasing the size of the nanoparticles has led to a ‘negative’ electrocatalytic effect, likely resulting from the changed reaction intermediate adsorption on the gold surface.

Bottom Line: The transformation over the last decade of the level of modelling and simulation of experiments has realised major advances such that electrochemical techniques can be fully developed and applied to real chemical problems of distinct complexity.This review focuses on the topic areas of: multistep electrochemical processes, voltammetry in ionic liquids, the development and interpretation of theories of electron transfer (Butler-Volmer and Marcus-Hush), advances in voltammetric pulse techniques, stochastic random walk models of diffusion, the influence of migration under conditions of low support, voltammetry at rough and porous electrodes, and nanoparticle electrochemistry.The review of the latter field encompasses both the study of nanoparticle-modified electrodes, including stripping voltammetry and the new technique of 'nano-impacts'.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford South Parks Road, Oxford, OX1 3QZ, UK.

ABSTRACT
Recent progress in the theory and practice of voltammetry is surveyed and evaluated. The transformation over the last decade of the level of modelling and simulation of experiments has realised major advances such that electrochemical techniques can be fully developed and applied to real chemical problems of distinct complexity. This review focuses on the topic areas of: multistep electrochemical processes, voltammetry in ionic liquids, the development and interpretation of theories of electron transfer (Butler-Volmer and Marcus-Hush), advances in voltammetric pulse techniques, stochastic random walk models of diffusion, the influence of migration under conditions of low support, voltammetry at rough and porous electrodes, and nanoparticle electrochemistry. The review of the latter field encompasses both the study of nanoparticle-modified electrodes, including stripping voltammetry and the new technique of 'nano-impacts'.

No MeSH data available.


Related in: MedlinePlus