Showing papers on "Cyclic voltammetry published in 1984"
TL;DR: In this article, the authors indique les procedes pour la mesure et le report des potentiels d'electrode dans des solvants non aqueux, vis-a-vis de ces systemes redox de reference.
Abstract: On montre que les couples redox ferrocene/ion ferricenium, [ferrocene: bis(η-cyclopentadienyl) fer(II)] et bis(biphenyl) chrome(I)/bis(biphenyl)-chrome(o) peuvent etre utilises comme systemes redox de reference. On indique les procedes pour la mesure et le report des potentiels d'electrode dans des solvants non aqueux, vis-a-vis de ces systemes redox de reference. Donnees numeriques obtenues dans 22 solvants organiques
1,168 citations
TL;DR: In this article, it was shown that the initial step in the formation of all polypyrrole films is a nucleation process and that all the electrochemical data resembles that for the nucleation and growth of a metal film.
516 citations
TL;DR: The cyclic voltammetry has the further attraction of providing information not only on the thermodynamics of redox processes but also on the kinetics of heterogeneous electron-transfer reactions and coupled chemical reactions as discussed by the authors.
Abstract: Polarography is still the best known classical measuring method in electroanalytical chemistry. However, in recent years its position has been challenged by cyclic voltammetry (CV). Simple diagnostic criteria and relatively easily acquired measuring techniques have hastened this development. Cyclic voltammetry has the further attraction of providing information not only on the thermodynamics of redox processes but also on the kinetics of heterogeneous electron-transfer reactions and coupled chemical reactions. The characteristic shapes of the voltammetric waves and their unequivocal position on the potential scale virtually fingerprint the individual electrochemical properties of redox systems. For this reason the method has been labeled “electrochemical spectroscopy”.
497 citations
TL;DR: In this paper, the electrochromic reactions of polyaniline film-coated electrodes were investigated in acid solutions in the potential range between −0.2 V and 0.6 V vs. SCE, where the color of the film changes from transparent yellow to green depending on the potential.
384 citations
TL;DR: Mecanisme de la degradation du film avec formation de p-benzoquinone et differences dans les proprietes electrochimiques des films de polyaniline reportees jusqu'ici as mentioned in this paper.
348 citations
TL;DR: A simple analysis of the capacitive currents associated with the cyclic voltammetric switching of a polypyrrole film between its reduced (insulating) and oxidized (electronically conducting) states offers a reasonably precise description of the form of the voltammogram.
Abstract: A simple analysis of the capacitive currents associated with the electrochemical (cyclic voltammetric) switching of a polypyrrole film between its reduced (insulating) and oxidized (electronically conducting) states offers a reasonably precise description of the form of the voltammogram. The theory demonstrates that a unique value for the faradaic component of the switching current cannot be extracted from the cyclic voltammetric data. Thus the number of electrons per pyrrole, ..gamma.., required for switching cannot be uniquely determined. Reported results of gaseous oxidation of a pyrrole film (by O/sub 2/, FeCl/sub 3/, or I/sub 2/) which produces optical and conductance changes comparable to those observed during electrochemical switching also indicate a comparable degree of oxidation (determined by % weight uptake of the oxidant). Here too, irresolvable faradaic and capacitive electron-transfer components render ..gamma.. indeterminate. The same analysis resolved the seemingly anomalous cyclic voltammetric behavior of polythiophene (another electrochemically switched polymer) and in principle is applicable to any polymer or film which can be electrochemically switched from an insulating to an electronically conducting state. 30 references, 6 figures.
307 citations
01 Jan 1984
TL;DR: In this paper, a new technique is presented which allows the gaseous and volatile products of electrochemical reactions to be measured quantitatively and with high sensitivity, and the equipment consists of the electrochemical cell, the membrane inlet system and the mass spectrometer.
Abstract: A new technique is presented which allows the gaseous and volatile products of electrochemical reactions to be measured quantitatively and with high sensitivity. The equipment consists of the electrochemical cell, the membrane inlet system and the mass spectrometer. Products being formed at the porous working electrode are sucked through the porous membrane into the ion source of the mass spectrometer. The mass intensity detected is proportional to the corresponding faradaic current. A rate of formation of 5 · 10−11 mol s−1 can well be measured. The rise time of the mass intensity is short enough to allow it to be quantitatively correlated to the faradaic current even at variing electrode potential. This is utilized in mass spectroscopic cyclic voltammetry. The feasibility of the method is described.
221 citations
TL;DR: In this paper, the authors propose a voltammetrie cyclique de la reduction of plusieurs types of complexes, e.g., [Et 3 NH] 2 [Ti(cat) 3 ], K 4 [TiO(Cat) 2 ] 2.9H 2 O, [T 3 NH], [TiDTBc] 2 (HDTBC)] 2.2CHCl 3.
Abstract: Preparation de plusieurs types de complexes dont [Et 3 NH] 2 [Ti(cat) 3 ], K 4 [TiO(cat) 2 ] 2 .9H 2 O, [Et 3 NH] 2 [Ti(DTBc) 2 (HDTBC)] 2 .2CHCl 3 . Etude de leurs structures. Etude par voltammetrie cyclique de la reduction
216 citations
TL;DR: In this article, the corrosion of ruthenium during oxygen evolution in 0.5 M H2SO4 was investigated using cyclic voltammetry, the rotating ring disc electrode technique and differential reflectance spectroscopy.
189 citations
TL;DR: In this article, a general mechanistic scheme involving both interfacial electrostatic and chemical interactions is proposed for cytochrome c electrode reactions, and it is concluded that electron transfer between an electrode surface and the exposed heme edge of properly oriented cyto-chrome c molecules involves maximum distances of ca. 0.6-0.9 nm.
189 citations
TL;DR: In this paper, a pâte de carbone modifiee chimiquement par le cobalt phtalocyanine and application a l'analyse chromatographique de l'hydrasine.
Abstract: Construction d'une electrode a pâte de carbone modifiee chimiquement par le cobalt phtalocyanine et application a l'analyse chromatographique de l'hydrasine
TL;DR: In this article, it was shown that the surface properties of carbon electrodes can have profound effects on the observed voltammetry, and that pretreatment of carbon fiber electrodes with a high current density results in a significant shift of the voltammetric waves for both compounds to potentials where they are more easily electrolyzed.
Abstract: Carbon electrodes are frequently used for electroanalytical studies of oxidizable compounds. However, for many compounds, heterogeneous charge-transfer rates are very slow at carbon electrodes, leading to illdefined voltammograms. Ascorbic acid (vitamin C) is perhaps one of the best examples of such phenomena, with a peak potential that is approximately 350 mV more positive at most carbon surfaces than at mercury electrodes. Ferricyanide also exhibits voltammetry at carbon electrodes that is less reversible than at noble metal electrodes. Various electrode surface treatments have been employed to accelerate the rates of ascorbate and ferricyanide electrolysis. Pretreatment of carbon fiber electrodes with a high current density results in a significant shift of the voltammetric waves for both compounds to potentials where they are more easily electrolyzed. Similar results are obtained with glassy carbon surfaces that have been heated at 500/sup 0/C under reduced pressure. An alternate method to increase reversibility is the judicious use of polishing procedures. Thus, it appears that the surface properties of carbon electrodes can have profound effects on the observed voltammetry.
TL;DR: In this paper, the cyclic voltammetry of materials prepared in both CH3CN and in the neutral melt has been investigated in the AlCl3:BuPyCl molten salt system and in CH 3CN.
Abstract: : Oxidative electrochemical polymerization of pyrrole has been shown to occur in the 1:1 mole ratio AlCl3:N-(l-butyl)pyridinium chloride((BuPyCl) molten salt at 40 C. Polypyrrole cannot be prepared in analogous 0.8:1 (basic) or 1.2:1 (acidic) mole ratio melts. The polypyrrole prepared in the molten salt is electrochemically similar to polypyrrole prepared in acetonitrile; both materials are conductors when oxidizes, can be used as electrode materials for the electrochemistry of solution species (eg ferrocene) and are oxidized and reduced at ca. -200 mV vs SSCE in CH3CN. The cyclic voltammetry of materials prepared in both CH3CN and in the neutral melt has been investigated in the AlCl3:BuPyCl molten salt system and in CH3CN. The most significant differences appear in the kinetics of the redox chemistry. The most facile behavior was observed in a 0.8:1 melt with polypyrrole prepared in the 1:1 melt. (Author)
TL;DR: In this article, the authors present a study of the luminescence of metal-metal complexes, e.g., mono and bimetallique complexes, with respect to absorption, emission, and resonance.
Abstract: Spectre d'absorption, d'emission et de resonance Raman des complexes cites. L'etude de la luminescence des complexes mono et bimetallique montre que l'interaction metal-metal est relativement faible
TL;DR: In this paper, a review of the literature on ion transfer at the interface of two immiscible electrolyte solutions is presented, with a focus on facilitated ion transfer and electron transfer across ITIES.
TL;DR: Le courant de pic voltammetrique a balayage lineaire obtenu est directement proportionnel a la concentration en As(III) dans le domaine 5 μM-2 mM avec une limite de detection de 3,5 μM as discussed by the authors.
Abstract: Le courant de pic voltammetrique a balayage lineaire obtenu est directement proportionnel a la concentration en As(III) dans le domaine 5 μM-2 mM avec une limite de detection de 3,5 μM
TL;DR: In this article, a microvoltammetriques for etudier loxydation d'anthracene et de diphenyl-9,10 anthracene, dans des solvants aprotiques (acetonitrile, chlorure de methylene and dimethoxyethane) en presence de perchlorate de tetrabutylammonium.
Abstract: Utilisation d'electrodes microvoltammetriques pour etudier l'oxydation d'anthracene et de diphenyl-9,10 anthracene, dans des solvants aprotiques (acetonitrile, chlorure de methylene et dimethoxyethane) en presence de perchlorate de tetrabutylammonium
TL;DR: In this paper, the authors compared the electrode potentials of ferrocene/ferricenium ion and bis(biphenyl)chromium(O)/bis(biphippyl) chromium(I) ion for different solvents obtained by polarography and cyclic voltammetry.
TL;DR: In this paper, the reduction electrochimique d'oxygene, en presence d'une electrode tournante a disque et anneau de graphite, recouverte de complexes de Co(II) avec l'anthrylene-1,9-5,5' bis-porphyrine-(octaethyl octamethyl) ou la biphenylenylene-1.8-5.5'
Abstract: Etudes de la reduction electrochimique d'oxygene, en presence d'une electrode tournante a disque et anneau de graphite, recouverte de complexes de Co(II) avec l'anthrylene-1,9-5,5' bis-porphyrine-(octaethyl octamethyl) ou la biphenylenylene-1,8-5,5' bis-porphyrine(octaethyl octamethyl)
TL;DR: The surface of a platinum electrode was anodically polarized at 3 V vs standard hydrogen electrode in 1 N H2SO4 at 300 K for 16 h so that a thick uniform oxidation layer was formed as discussed by the authors.
TL;DR: In this article, the first step in the formation of poly-N -methylpyrrole is again a nucleation process followed by growth of the nuclei to a continuous film.
TL;DR: In this paper, the role of the electrode material, the effect of the structure of the organic compound, and the role in the composition of the electrolytic solution is investigated with the help of various organic compounds (formic acid, methanol, ethanol, ethylene-glycol, C-2 compounds derived from ethylene glycol, butanol isomers) using cyclic voltammetry at the macroscopic level and infrared spectroscopy (either FTIRS or EMIRS) at the microscopic level.
TL;DR: In this paper, the authors studied the oxidation of l -ascorbic acid in sulphuric acid solutions at a bright platinum electrode, by employing cyclic voltammetry, controlledpotential electrolysis and potential-step measurements.
TL;DR: In this article, the influence of the ohmic potential drop at the microelectrodes has been estimated and found to be smaller than for infinitely large electrodes, and the sensitivity in analytical applications is increased when significant overlap of adjacent diffusion layers is reached.
TL;DR: In this paper, the results of a study on spin electronique permettant de determiner la structure, la stabilite et le comportement d'oxydation des complexes de Ni(II) and de Cu(II), avec des tetramines macrocycliques comprenant des cycles a 13-15 membres, des nombres differents d'anions imido (de 0 a 3) and des substituants phenyle, pyridyle and pyridine N-oxyde extraplanaires.
Abstract: Resultats d'etudes potentiometriques, electrochimiques, spectrochimiques et de resonance de spin electronique permettant de determiner la structure, la stabilite et le comportement d'oxydation des complexes de Ni(II) et de Cu(II) avec des tetramines macrocycliques comprenant des cycles a 13-15 membres, des nombres differents d'anions imido (de 0 a 3) et des substituants phenyle, pyridyle et pyridine N-oxyde extraplanaires
TL;DR: In this article, les etudes de voltammetrie cyclique dans le cas d'un lit de microelectrodes d'or, dans des solutions de H 2 SO 4 1N and de HF 1N agitees par N 2, en fonction de la vitesse de balayage and du domaine de potentiels balaye.
Abstract: Donnees sur les etudes de voltammetrie cyclique dans le cas d'un lit de microelectrodes d'or, dans des solutions de H 2 SO 4 1N et de HF1N agitees par N 2 , en fonction de la vitesse de balayage et du domaine de potentiels balaye. On montre que H 2 et O 2 sont tres legerement adsorbes sur Au et que rien n'est dissous dans le metal en masse. Ces faits indiquent que l'electrode d'or est une electrode indicatrice plus stable que Pt, qui dissout l'oxygene
TL;DR: In this paper, it was shown that the initial deposit even in K+ solution is invariably the insoluble form, being then converted into the soluble form, irrespective of electrochemical conditions or solution composition.
Abstract: Films of Prussian Blue (PB) deposited by electroreduction in the absence of K + have absorbance maxima at 730 nm which narrow and shift on voltammetric cycling in KCI solution to 690 nm, these absorptions being deemed diagnostic of 'insoluble' and 'soluble' PB respectively. Spectroelectro- chemistry shows that the initial deposit even in K+ solution is invariably the insoluble form, being then converted into the soluble, irrespective of electrochemical conditions or solution composition ; this resolves several problems in the current literature. Electrochemical oxidation of PB gives continuous mixed-valence compositions up to complete oxidation ; by contrast, reduction to Prussian White involves clean conversion of one into the other at a critical potential.
TL;DR: In this article, it was shown that a layer of p-type Cu 2 O is formed initially by the oxidation of Cu on the forward sweep of the cyclic voltammogram and that the thickness of the layer increases on the reverse sweep as an overlayer of Cu(OH) 2 or CuO is reduced to Cu2 O.
TL;DR: In this article, a single crystal Au(100) electrode in 1N H 2 SO 4 electrolyte has been potentiostatically polarized at potentials from 0.8 to 4.0 V versus standard hydrogen electrode (SHE).