The Experts below are selected from a list of 13035 Experts worldwide ranked by ideXlab platform
Richard G. Compton - One of the best experts on this subject based on the ideXlab platform.
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Metal deposition and stripping under self-supported conditions: Experiment and simulation
Journal of Electroanalytical Chemistry, 2019Co-Authors: Minjun Yang, Christopher Batchelor-mcauley, Richard G. ComptonAbstract:Abstract To what extent does the mass-transport to and from an electrochemical interface change when the dimensions of the electrode are comparable to the Debye length of the system? This work develops a theoretical model for the deposition and stripping of a metal from an electrode accounting for finite electrolyte concentrations. When the electrode is large compared to the Debye length Electroneutrality holds and migration significantly influences the mass-transport of ions in the vicinity of the electrode, altering the electrochemical current. However, simulations predict that when the electrode is comparable to or smaller than the Debye length of the system then the influence of migration is minimised. In the experiment, the steady-state reductive flux for the deposition of silver to a microelectrode is shown to deviate from that expected on the basis of Electroneutrality and is compared with simulation while the results also show an altered rate of metal nucleation in the absence of additional supporting electrolyte.
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The Electroneutrality approximation in electrochemistry
Journal of Solid State Electrochemistry, 2011Co-Authors: Edmund J. F. Dickinson, Juan G. Limon-petersen, Richard G. ComptonAbstract:The Electroneutrality approximation assumes that charge separation is impossible in electrolytic solutions. It has a long and successful history dating back to 1889 and may be justified because of the small absolute values for the permittivities of typical solvents. Dimensional analysis shows that the approximation becomes invalid only at nanosecond and nanometre scales. Recent work, however, has taken advantage of the capabilities of modern numerical simulation in order to relax this approximation, with concomitant advantages such as avoiding paradoxes and permitting a clear and consistent 'physical picture' to describe charge dynamics in solution. These new theoretical techniques have been applied to liquid junction potentials and weakly supported voltammetry, with strong experimental corroboration for the latter. So long as dynamic processes are being studied, for which analytical solutions are unavailable in any case, numerical simulation is shown to render Electroneutrality unnecessary as an a priori assumption. © 2011 Springer-Verlag
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The Electroneutrality approximation in electrochemistry
Journal of Solid State Electrochemistry, 2011Co-Authors: Edmund J. F. Dickinson, Juan G. Limon-petersen, Richard G. ComptonAbstract:The Electroneutrality approximation assumes that charge separation is impossible in electrolytic solutions. It has a long and successful history dating back to 1889 and may be justified because of the small absolute values for the permittivities of typical solvents. Dimensional analysis shows that the approximation becomes invalid only at nanosecond and nanometre scales. Recent work, however, has taken advantage of the capabilities of modern numerical simulation in order to relax this approximation, with concomitant advantages such as avoiding paradoxes and permitting a clear and consistent ‘physical picture’ to describe charge dynamics in solution. These new theoretical techniques have been applied to liquid junction potentials and weakly supported voltammetry, with strong experimental corroboration for the latter. So long as dynamic processes are being studied, for which analytical solutions are unavailable in any case, numerical simulation is shown to render Electroneutrality unnecessary as an a priori assumption.
Dominique Luneau - One of the best experts on this subject based on the ideXlab platform.
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mononuclear manganese iii complexes with reduced imino nitroxide radicals by single electron transfer and intermolecular hydrogen bonds as an intramolecular structural driving force
Dalton Transactions, 2019Co-Authors: Constance Lecourt, Warren Madanamoothoo, Vivian Ferreol, Nicolas Belangerdesmarais, Lhoussain Khrouz, Jeanbernard Tommasino, Christian Reber, Cedric Desroches, Dominique LuneauAbstract:Manganese(III) complexes were synthesized by one-electron transfer from a Mn(II) ion to the imino nitroxide radical 2-(2-imidazolyl)-4,4,5,5-tetramethylimidazoline-1-oxyl (IMImH) in methanol. After the manganese ions attained the +III oxidation state, the imino nitroxide radicals were found to be irreversibly reduced in the complexes. Depending on the synthesis conditions, two complexes differing by their counter-anions were isolated as single crystals. These are [Mn(IMHIm)2(MeOH)2]ClO4·H2O (1) and [Mn(IMHIm)2(MeOH)2]PF6 (2), which crystallize in the monoclinic P21/n and triclinic P space groups, respectively. The two complexes show Jahn–Teller distortions typical of Mn(III) centres and only reduced radicals are coordinated, as indicated by the N–O bond lengths and Electroneutrality. In addition, the crystal structure analyses reveal two intermolecular hydrogen bonding networks. One involves counter-anions, water molecules and reduced radicals, and the other involves coordinated methanol molecules and imidazole moieties. These intermolecular interactions are driving forces that stabilize the two complexes. They also suggest that the tautomer is in the amino imine-oxide form after reduction of the radical and reveal the deprotonation of the imidazole ring, which is required for Electroneutrality. This assessment is supported by single-crystal X-ray diffraction, EPR and Raman spectroscopy as well as magnetic and electrochemical studies.
Alan M. Bond - One of the best experts on this subject based on the ideXlab platform.
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How valid is the Electroneutrality approximation in the theory of steady-state voltammetry?
Journal of Electroanalytical Chemistry, 2001Co-Authors: Keith B. Oldham, Alan M. BondAbstract:We carry out two accurate analyses, one with and one without the Electroneutrality approximation, of conditions attending the steady-state voltammetry of the reversible M/M n + reaction at a small hemispherical electrode in a solution containing only a single n:n electrolyte. In the absence of Electroneutrality, the electroactive cation and its counterion are assumed to have equal concentrations only in the bulk. The discrepancy between the shapes of the two voltammograms is significant only for very small electrodes at which the ionic strength is low and is therefore unlikely to be detectable experimentally. Accordingly, this study lends credence to the validity of voltammetric theories based on the Electroneutrality assumption. As well as predicting the small effect that the Electroneutrality assumption has on the voltammogram, quantitative predictions are made of other properties of the system, including the ionic concentration, potential and charge profiles. A mild space charge, invariably positive, is found to occupy a region, of width comparable to the electrode radius, adjacent to the working electrode. This faradaically created space charge has properties distinctly different from those characteristic of traditional double layers. © 2001 Elsevier Science B.V. All rights reserved.
Constance Lecourt - One of the best experts on this subject based on the ideXlab platform.
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mononuclear manganese iii complexes with reduced imino nitroxide radicals by single electron transfer and intermolecular hydrogen bonds as an intramolecular structural driving force
Dalton Transactions, 2019Co-Authors: Constance Lecourt, Warren Madanamoothoo, Vivian Ferreol, Nicolas Belangerdesmarais, Lhoussain Khrouz, Jeanbernard Tommasino, Christian Reber, Cedric Desroches, Dominique LuneauAbstract:Manganese(III) complexes were synthesized by one-electron transfer from a Mn(II) ion to the imino nitroxide radical 2-(2-imidazolyl)-4,4,5,5-tetramethylimidazoline-1-oxyl (IMImH) in methanol. After the manganese ions attained the +III oxidation state, the imino nitroxide radicals were found to be irreversibly reduced in the complexes. Depending on the synthesis conditions, two complexes differing by their counter-anions were isolated as single crystals. These are [Mn(IMHIm)2(MeOH)2]ClO4·H2O (1) and [Mn(IMHIm)2(MeOH)2]PF6 (2), which crystallize in the monoclinic P21/n and triclinic P space groups, respectively. The two complexes show Jahn–Teller distortions typical of Mn(III) centres and only reduced radicals are coordinated, as indicated by the N–O bond lengths and Electroneutrality. In addition, the crystal structure analyses reveal two intermolecular hydrogen bonding networks. One involves counter-anions, water molecules and reduced radicals, and the other involves coordinated methanol molecules and imidazole moieties. These intermolecular interactions are driving forces that stabilize the two complexes. They also suggest that the tautomer is in the amino imine-oxide form after reduction of the radical and reveal the deprotonation of the imidazole ring, which is required for Electroneutrality. This assessment is supported by single-crystal X-ray diffraction, EPR and Raman spectroscopy as well as magnetic and electrochemical studies.
Keith B. Oldham - One of the best experts on this subject based on the ideXlab platform.
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How valid is the Electroneutrality approximation in the theory of steady-state voltammetry?
Journal of Electroanalytical Chemistry, 2001Co-Authors: Keith B. Oldham, Alan M. BondAbstract:We carry out two accurate analyses, one with and one without the Electroneutrality approximation, of conditions attending the steady-state voltammetry of the reversible M/M n + reaction at a small hemispherical electrode in a solution containing only a single n:n electrolyte. In the absence of Electroneutrality, the electroactive cation and its counterion are assumed to have equal concentrations only in the bulk. The discrepancy between the shapes of the two voltammograms is significant only for very small electrodes at which the ionic strength is low and is therefore unlikely to be detectable experimentally. Accordingly, this study lends credence to the validity of voltammetric theories based on the Electroneutrality assumption. As well as predicting the small effect that the Electroneutrality assumption has on the voltammogram, quantitative predictions are made of other properties of the system, including the ionic concentration, potential and charge profiles. A mild space charge, invariably positive, is found to occupy a region, of width comparable to the electrode radius, adjacent to the working electrode. This faradaically created space charge has properties distinctly different from those characteristic of traditional double layers. © 2001 Elsevier Science B.V. All rights reserved.