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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

Diagram for the calculation of the minimal distance, dmin, to a blocking molecule, at which a nanoparticle can touch the electrode surface (impact). Reproduced with permission from Ref. 177 Copyright 2014, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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fig29: Diagram for the calculation of the minimal distance, dmin, to a blocking molecule, at which a nanoparticle can touch the electrode surface (impact). Reproduced with permission from Ref. 177 Copyright 2014, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mentions: One significant observation for impact experiments is that the recorded collision frequency is not uncommonly below that theoretically predicted.171b This observation has previously been explained solely in terms of solution-phase agglomeration/aggregation.175 However, other causes for such effects need to be considered. In many experimental cases the working electrodes used tend to be micron sized wires sealed in glass. Consequently, if the nanoparticles of study also adhere to the inert (glass) substrate surrounding the electrode, then the frequency of observed nanoparticle impacts may be significantly reduced due to diffusional shielding.176 A further issue arises upon consideration of the dimensions of nanoparticle as compared to a molecule. As a result of the geometrical constraints of an impacting nanoparticle, the ‘nano-impact’ experiment will be inherently more sensitive to the presence of adsorbing and blocking organic media than conventional molecular redox probes.177 Figure 29 depicts a simple geometric model showing how the presence of surface-adsorbed species leads to efficient blocking of the electrode surface towards nanoparticles due to the magnitude of the minimum distance (dmin) of an impacting nanoparticle to the blocking molecule. The magnitude of this minimum distance of approach depends upon both the radius of the nanoparticle (rp) and the height of the adsorbed species (hb). Hence, the observed decreased impact frequency may not just be related to agglomeration or aggregation of the nanoparticles in solution, but may also arise due to factors relating to the electrode and the electrode design itself.


Recent Advances in Voltammetry.

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

Diagram for the calculation of the minimal distance, dmin, to a blocking molecule, at which a nanoparticle can touch the electrode surface (impact). Reproduced with permission from Ref. 177 Copyright 2014, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig29: Diagram for the calculation of the minimal distance, dmin, to a blocking molecule, at which a nanoparticle can touch the electrode surface (impact). Reproduced with permission from Ref. 177 Copyright 2014, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mentions: One significant observation for impact experiments is that the recorded collision frequency is not uncommonly below that theoretically predicted.171b This observation has previously been explained solely in terms of solution-phase agglomeration/aggregation.175 However, other causes for such effects need to be considered. In many experimental cases the working electrodes used tend to be micron sized wires sealed in glass. Consequently, if the nanoparticles of study also adhere to the inert (glass) substrate surrounding the electrode, then the frequency of observed nanoparticle impacts may be significantly reduced due to diffusional shielding.176 A further issue arises upon consideration of the dimensions of nanoparticle as compared to a molecule. As a result of the geometrical constraints of an impacting nanoparticle, the ‘nano-impact’ experiment will be inherently more sensitive to the presence of adsorbing and blocking organic media than conventional molecular redox probes.177 Figure 29 depicts a simple geometric model showing how the presence of surface-adsorbed species leads to efficient blocking of the electrode surface towards nanoparticles due to the magnitude of the minimum distance (dmin) of an impacting nanoparticle to the blocking molecule. The magnitude of this minimum distance of approach depends upon both the radius of the nanoparticle (rp) and the height of the adsorbed species (hb). Hence, the observed decreased impact frequency may not just be related to agglomeration or aggregation of the nanoparticles in solution, but may also arise due to factors relating to the electrode and the electrode design itself.

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