The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Christian Amatore - One of the best experts on this subject based on the ideXlab platform.
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Theoretical analysis of microscopic Ohmic Drop effects on steady-state and transient voltammetry at the disk microelectrode: a quasi-conformal mapping modeling and simulation.
Analytical Chemistry, 2008Co-Authors: Christian Amatore, Alexander Oleinick, Irina SvirAbstract:The effect of uncompensated solution resistance on steady-state and transient voltammograms at the disk microelectrode was for the first time treated theoretically and numerically at the microscopic level using specific quasi-conformal mapping for the case of absence of electric migration. It has been shown that microscopic distributions of electric potential and current density at a disk microelectrode affect the voltammetric waves at different degrees across the electrode surface due to the variation of elementary resistances and elementary current fluxes over the electrode surface which leads to nonlinear effects that have not been discussed in existing theoretical treatments of Ohmic Drop at microelectrodes. The analysis of steady state voltammetry in strongly resistive media under Nernstian conditions has allowed justification by appropriate analytical derivations of the widely used potential-shift correction of steady state voltammograms by plotting i vs (E − iRe).
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Ohmic Drop compensation in cyclic voltammetry at scan rates in the megavolt per second range access to nanometric diffusion layers via transient electrochemistry
Journal of Electroanalytical Chemistry, 2000Co-Authors: Christian Amatore, Emmanuel Maisonhaute, Gerard SimonneauAbstract:A new concept of a three-electrode potentiostat involving positive feedback compensation of Ohmic Drop is discussed. This potentiostat allows the electrochemical investigation of nanosecond time scales by allowing the recording of Ohmic Drop-free voltammograms at scan rates in the megavolt per second range. This range of scan rate corresponds to the development of diffusion layers having only a few nanometers thickness. The principle and properties of the potentiostat are first demonstrated analytically based on a simplified equivalent circuit for the conditions used in this study (v<5 MV s−1). The validity of this simplified analytical approach is then tested and further investigated by precise simulations of the electronic properties of the real circuit, and then by experimental tests on RC dummy cells or on dummy cells equipped with a pseudo-faradaic impedance. These tests establish that the potentiostat behaves excellently up to slightly above 2 MV s−1. These results were then confirmed by examination of the reduction voltammetry of anthracene in highly concentrated (0.9 M) supporting electrolyte to avoid interference with transport in the double layer, since usual supporting electrolyte concentrations would produce double layers of the same thicknesses as the diffusion layers that are created in this range of scan rates. These tests confirmed the results of the above investigations and finally demonstrated that this potentiostat allows the recording of undistorted voltammograms up to 2.25 MV s−1.
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Ohmic Drop compensation in cyclic voltammetry at scan rates in the megavolt per second range: access to nanometric diffusion layers via transient electrochemistry
Journal of Electroanalytical Chemistry, 2000Co-Authors: Christian Amatore, Emmanuel Maisonhaute, Gerard SimonneauAbstract:A new concept of a three-electrode potentiostat involving positive feedback compensation of Ohmic Drop is discussed. This potentiostat allows the electrochemical investigation of nanosecond time scales by allowing the recording of Ohmic Drop-free voltammograms at scan rates in the megavolt per second range. This range of scan rate corresponds to the development of diffusion layers having only a few nanometers thickness. The principle and properties of the potentiostat are first demonstrated analytically based on a simplified equivalent circuit for the conditions used in this study (v
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ultrafast cyclic voltammetry performing in the few megavolts per second range without Ohmic Drop
Electrochemistry Communications, 2000Co-Authors: Christian Amatore, Emmanuel Maisonhaute, Gerard SimonneauAbstract:A new concept of a three-electrode potentiostat involving positive feedback compensation of Ohmic Drop is used to investigate nanosecond time scales by allowing the recording of Ohmic Drop-free voltammograms at scan rates of a few megavolts per second. This range of scan rates corresponds to the development of diffusion layers whose widths are only a few nanometers thick. Independent tests on dummy cells (Bode plots) demonstrated that the potentiostat behaved excellently in the megavolt per second range. Examination of the well-established voltammetric reduction of anthracene in highly concentrated (0.9 M) supporting electrolyte confirmed that this potentiostat allowed the recording of undistorted Ohmic Drop-free voltammograms up to 2.25 MV s−1.
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Steady state voltammetry at low electrolyte/reactant concentration ratios: what it means and what it does not mean
Journal of Electroanalytical Chemistry, 1999Co-Authors: Christian Amatore, Laurent Thouin, M. Fátima BentoAbstract:Abstract Voltammetric measurements performed at low [electrolyte]/[reactant] ratios are affected by migrational transport, as well as by Ohmic Drop contributions. The latter depend on the current as well as on the charge of the initial electroactive species because the local electrolysis changes the ionic composition in the vicinity of the electrode. Extraction of thermodynamic or kinetic data from wave shapes and positions is thus impossible without correction of these Ohmic Drop components. This work extends a previous experimental approach for eliminating Ohmic Drop contributions from experimental voltammograms obtained at low [electrolyte]/[reactant] ratios, by combining impedance measurements and voltammetric data. The results presented here confirm our previous independent conclusions that when the reactant is neutral, the variation of Ohmic Drop along the voltammetric curve (which reflects the progressive ionic enrichment of the diffusion layer) cannot be predicted by considering diffusional/migrational transport alone, but also requires consideration of the influence of natural convection.
F Vicente - One of the best experts on this subject based on the ideXlab platform.
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Spatiotemporal colorimetry to reveal electrochemical kinetics of poly(o-toluidine) films along ITO surface
Electrochimica Acta, 2018Co-Authors: J. Agrisuelas, J. J. García-jareño, F VicenteAbstract:Sheet resistance of transparent conducting electrodes can affect dramatically the electrochromic response of surface confined active species in any electrochromic device. The generated gradient of effective potential on the electrode surface has a direct impact on the electrochemical kinetics of these species. In this work, the electrochromic poly (o-toluidine) (POT) film, a derivative polyaniline, was deposited along a narrow, long transparent indium tin oxide (ITO) supporting electrode with a sheet resistivity of 30 Ω cm−1. This configuration was used as a model to simulate a surface electrical conduction from the external metallic contact to the opposite extreme of ITO with an important and increasing Ohmic Drop from 30 Ω to 170 Ω. The color changes on the electrode surface were investigated and parametrized by RGB digital video. The spatiotemporal analysis of color intensity in the red, green and blue channels allowed three electrochromic transitions of POT to be separated. For the first time, the pattern of POT electrochemical kinetics along the electrode surface was revealed. For that, apparent electromonochromatic coefficients were calculated to convert the adimensional RGB intensities to electrochemical currents. The results were explained using a numerical finite difference model varying the Ohmic Drop and film thickness. The methodology here exposed can be used to characterize electrochemical response of electrochromic devices.
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Ohmic Drop of prussian blue graphite epoxy electrodes
Electrochimica Acta, 1999Co-Authors: J Trijueque, J J Garciajareno, J Navarrolaboulais, A Sanmatias, F VicenteAbstract:Abstract Ohmic Drop effects on the voltammogram shape of the Prussian-blue⇌Everitt’s salt system have been studied by considering the electroactive film model. As the uncompensated resistance varies, the experimental characteristic curve parameters also varies. A dependence of the voltammograms with the graphite proportion was found related with the Ohmic Drop due to the composite electrodes. The optimal graphite proportion to obtain a good faradaic-to-charge current ratio was 62% in weight which coincides with the second percolation threshold. The Ohmic overpotential, which relates the Ohmic Drop with the electrochemical magnitudes, is also minimum at this proportion.
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chronoamperometry of prussian blue films on ito electrodes Ohmic Drop and film thickness effect
Electrochimica Acta, 1999Co-Authors: J J Garciajareno, J Navarrolaboulais, A Sanmatias, F VicenteAbstract:Abstract The chronoamperograms associated with the reduction of prussian blue films deposited onto indium tin oxide (ITO) electrodes to the Everitt’s salt form, are influenced by the Ohmic Drop effect. These chronoamperometric curves have been simulated by means of a numerical finite difference model which is able to explain their shape and their dependence on the thickness of the film and on the uncompensated resistance. An analytical expression which describes the dependence of current against time at initial times considering the Ohmic Drop effect has also been proved when applied to these chronoamperometric curves at short times.
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Ohmic Drop effect on the voltammetric behaviour of graphite polyethylene composite electrodes
Journal of Electroanalytical Chemistry, 1997Co-Authors: J Navarrolaboulais, J J Garciajareno, J Trijueque, F VicenteAbstract:Graphite + polyethylene composites can be used as electrodes in electrochemical experiments because of their low charging current in contrast with other composite electrodes. However, the results reveal that the Ohmic Drop must always be considered in the data analysis. The peak potential and the peak current are related through an expression deduced for a Nernstian process where the mass transport is controlled by diffusion. The determination of the uncompensated resistance implies also the calculation of the convolution of the current.
L M Yudi - One of the best experts on this subject based on the ideXlab platform.
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Ohmic Drop effects in square wave voltammetry response for an ion transfer process at a liquid liquid interface
Journal of Electroanalytical Chemistry, 2005Co-Authors: A V Juarez, A M Baruzzi, L M YudiAbstract:Abstract The effect of Ohmic Drop on square-wave voltammetry experiments (SWV) at a liquid–liquid interface is analyzed. The study is based on the distortion of SW voltammetric profiles of the tetraethyl ammonium transfer process across the water/1,2-dichloroethane interface when an uncompensated resistance, R Ω , is present. Depending on the experimental conditions significant R Ω values arise as a consequence of the low electrical conductivity of the organic solvent characteristic of these systems, and efficient IR compensation is needed. When R Ω is not totally removed, a non-linear dependence of peak current (Δ I p ) on the square root of the frequency, an increase of half-peak width (Δ E p/2 ) and a shift of peak potential ( E p ) towards more positive values are observed in the SW profiles. The influence of signal frequency and R Ω values on SWV parameters (Δ I p , E p and Δ E p/2 ) is evaluated.
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Ohmic Drop effects in square-wave voltammetry response for an ion transfer process at a liquid–liquid interface
Journal of Electroanalytical Chemistry, 2005Co-Authors: A V Juarez, A M Baruzzi, L M YudiAbstract:Abstract The effect of Ohmic Drop on square-wave voltammetry experiments (SWV) at a liquid–liquid interface is analyzed. The study is based on the distortion of SW voltammetric profiles of the tetraethyl ammonium transfer process across the water/1,2-dichloroethane interface when an uncompensated resistance, R Ω , is present. Depending on the experimental conditions significant R Ω values arise as a consequence of the low electrical conductivity of the organic solvent characteristic of these systems, and efficient IR compensation is needed. When R Ω is not totally removed, a non-linear dependence of peak current (Δ I p ) on the square root of the frequency, an increase of half-peak width (Δ E p/2 ) and a shift of peak potential ( E p ) towards more positive values are observed in the SW profiles. The influence of signal frequency and R Ω values on SWV parameters (Δ I p , E p and Δ E p/2 ) is evaluated.
Jean-michel Savéant - One of the best experts on this subject based on the ideXlab platform.
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Ohmic Drop correction in electrochemical techniques multiple potential step chronoamperometry at the test bench
Energy Storage Materials, 2020Co-Authors: Cyril Costentin, Jean-michel SavéantAbstract:Abstract Ohmic Drop correction is an important issue in the practice of cyclic and linear sweep voltammetry. While this problem has received satisfactory solutions over the last decades, a new approach, “multiple potential step chronoamperometry (MUSCA)” has been recently proposed. At the test bench, application of MUSCA is not only disappointing but the cure is clearly worse than the disease, opening the way to dangerous artefacts in the interpretation of experimental data.
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conductive mesoporous catalytic films current distortion and performance degradation by dual phase Ohmic Drop effects analysis and remedies
Journal of Physical Chemistry C, 2016Co-Authors: C P Andrieux, Cyril Costentin, Jean-michel Savéant, Carlo Di Giovanni, Cedric TardAbstract:In the active interest aroused by catalysis of electrochemical reactions, particularly molecule activation related to modern energy challenges, mesoporous films deposited on electrodes are often preferred to catalysts homogeneously dispersed in solution. Conduction in the solid portion of the film and in the pores may strongly affect the characteristic catalytic Tafel plots, possibly leading to mechanistic misinterpretation and also degrade the catalytic performances. These Ohmic Drop effects take place, unlike those classically encountered with a massive electrode immersed in an electrolytic solution, in two different zones of the film, the solid bulk of the film and the pores, that are coupled together by a distributed capacitance and by the faradaic impedance representing the catalytic reaction located at their interface. A transmission line modeling allows the analysis of the capacitance charging responses as a function of only two dimensionless parameters in the framework of linear scan voltammetry: ...
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fast cyclic voltammetry at ultramicroelectrodes current measurement and Ohmic Drop positive feedback compensation by means of current feedback operational amplifiers
Journal of Electroanalytical Chemistry, 1990Co-Authors: D Garreau, Philippe Hapiot, Jean-michel SavéantAbstract:Abstract A current measurer for fast cyclic voltammetry at ultramicroelectrodes based on a current feedback operational amplifier is described. A factor of ca. 10 in bandwidth is thus gained as compared to previously described current measurers based on voltage feedback operational amplifiers, hence allowing the recording of cyclic voltammograms where the possible influence of the apparatus, distortion and even potential shift, is negligible up to several million volts per second. Using the same type of amplifier, an Ohmic Drop positive feedback compensation device in a two-electrode configuration was also designed, allowing an exact compensation without instrumental distortion of the faradaic response (error in the distance between cathodic and anodic peaks less than 10 mV) up to scan rates as high as 200,000 V s −1 . 500,000 V s −1 can be reached if an error of 30 mV is tolerated, corresponding to an uncertainty of 25% in the determination of a standard rate constant of 4 cm s−1.
Milivoj Lovric - One of the best experts on this subject based on the ideXlab platform.
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Ohmic Drop effects in square wave voltammetry
Journal of Electroanalytical Chemistry, 2001Co-Authors: Valentin Mirceski, Milivoj LovricAbstract:The Ohmic Drop effects in square-wave voltammetry (SWV) are studied theoretically. Three different electrode mechanisms are considered: (i) simple redox reaction of a dissolved redox couple, (ii) redox reaction with adsorption of the reactant and (iii) surface redox reaction of a strongly immobilized redox couple. The Ohmic Drop effect is represented through the complex dimensionless resistance parameter defined as ρ=(nF)2S(cOx)0(Df)1/2RΩ(RT)−1 for (i) and (ii) and ρs=(nF)2SΓ0RΩf(RT)−1 for (iii). The relationships between the properties of the SWV response and the resistance parameters are investigated thoroughly. An attempt is made to establish criteria for distinguishing the kinetic from the Ohmic Drop phenomena. The influence of the Ohmic Drop on the quasi-reversible maximum in the case of adsorption-complicated redox reactions (ii) and (iii) is analyzed. The error that can be involved in the estimation of the standard rate constant using the quasi-reversible maximum in the presence of Ohmic Drop is evaluated in the case of the surface redox reaction (iii).
