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Showing papers on "Cyclic voltammetry published in 1981"




Journal ArticleDOI
TL;DR: In this paper, four platinum-based binary catalysts were investigated for the electrochemical oxidation of methanol, and their performance was investigated by linear and cyclic voltammetry.

200 citations


Journal ArticleDOI
TL;DR: The cyclic voltammograms of the Cu electrode were obtained in NaOH solution as a function of the voltage scanning rate, electrolyte concentration and voltage range, and a correlation was made between three well-defined anodic peaks and their corresponding cathodic ones as mentioned in this paper.

172 citations


Journal ArticleDOI
TL;DR: In this paper, the H-Pt bond energy was found to be structure sensitive and sensitive both to local site geometry and long range order in the surface, and the specific contribution of atomic imperfections to the voltammetry curve was deduced from the ordered and countable imperfections occurring on high Miller index single crystal surfaces that have a stepped structure.

137 citations


Journal ArticleDOI
TL;DR: In this paper, the electrocatalytic activity of different alloys for methanol oxidation has been characterized by exchange current densities obtained from extrapolation of Tafel lines of calculated equilibrium potential.

122 citations


Journal ArticleDOI
TL;DR: In this paper, the initial electrocatalytic activity for oxygen evolution in acid electrolyte was determined using the potentiostatic method, and the surface areas of these oxides were estimated using cyclic voltammetry.
Abstract: Ruthenium oxide, prepared by the thermal decomposition method, has the highest known initial electrocatalytic activity for oxygen evolution in acid electrolyte. However, this material is not stable in the electrolyte and at the same time exhibits a significant increase of oxygen overpotential with time, probably due to a chemical transformation of the oxide from a lower to a higher valence state. Efforts were made to stabilize ruthenium by preparing mixed oxides with Ir and/or Ta using the thermal decomposition method. The electrocatalytic activities for oxygen evolution on these oxides in were determined using the potentiostatic method. The surface areas of these oxides were estimated using cyclic voltammetry. Dual Tafel slopes (approximately 30 and 40 mV) were found on most of these oxides. The ternary oxide exhibited a single Tafel slope of 30 mV, had the lowest overpotential, and showed minimum variation of overpotential with time.

110 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined the suitability of aquo iron (II)-iron (III)-complexes with o-phenanthroline and related ligands for electrochemical energy storage.
Abstract: Iron (III)-Iron (II) complexes with o-phenanthroline and related ligands have been examined by electrochemical techniques in aqueous H2SO4 media with respect to their suitability as redox couples for electrochemical energy storage. The iron (II) complexes undergo a rapid 1 electron oxidation at graphite and platinum electrodes to yield iron (III) complexes; these complexes showed varying stabilities depending on the nature of the substituents on the complexes. The iron (II) complexes examined in this study were formed with (i) monodentate, (ii) bidentate, or (iii) tridentate ligands. The redox couples have a higher E o value which has been a positive consideration in the storage. Although the aquo iron (II)- iron (III) couple has an E o less than the complexes, it certainly has shown "greater promise in terms of storage stability. The kinetics of iron (II) complexation~has been followed by cyclic voltammetry.

108 citations


Journal ArticleDOI
TL;DR: In this article, the same authors have observed an unusual pH effect has been observed in polymeric polymer films, where the unbound pyridyl groups in the polymer become deprotonated above pH 4 and up to pH 9.2.
Abstract: The known oxidative catalytic behavior of the ions (bpy)/sub 2/(py)RuO/sup 2 +/ (bpy is 2,2'-bipyridine; py is pyridine) and (trpy) (bpy)RuO/sup 2 +/ (trpy is 2,2',2''-terpyridine) has been successfully transferred to electrode surfaces. The electrodes were chemically modified by deposition of thin polymeric films containing the (bpy)/sub 2/(H/sub 2/0)Ru/sup II/ group bound to poly-4-vinylpyridine. Upon oxidation to Ru/sup IV/ on the surface catalytic oxidation currents are observed for the modified electrodes in the presence of 2-propanol, p-toluic acid, and the xylenes with an added surfactant. The effective catalytic lifetimes of the films are limited ( > 30 turnovers per redox site) by a competing reaction within the polymer film which changes the nature of the redox sites. An unusual pH effect has been observed in the polymer films. Below pH 4, potentials measured by cyclic voltammetry for the bound ((bpy)/sub 2/(OH)Ru/sup II/(py)-)/sup 2 +//((bpy)/sub 2/(OH/sub 2/)Ru/sup III/(py)-)/sup 2 +/ and ((bpy)/sub 2/(O)Ru/sup IV/(py)-)/sup 2 +//((bpy)/sub 2/(OH)Ru/sup III/(py)-)/sup 2 +/ couples change with pH as expected. Above pH 4, where the unbound pyridyl groups in the polymer become deprotonated, up to pH 9.2 the redox couples no longer respond to pH changes in the bulk solution. The difference in pH behaviormore » between the polymer in solution and on the electrode surface has allowed us to observe the deposition process by cyclic voltammetry. In acid solution, the polymer film is open and large amounts of ferri- or ferrocyanide ions can be incorporated reversibly into the films by ion exchange. Over a longer time period, the cyano ions are permanently bound in the films, apparently by the formation of a cyano-bridged Fe-Ru dimer.« less

106 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of small additions (2 w/o-4 w /o) of HgO, Tl2O3, PbO, CdO, In2O 3, In(OH)3, In and Ga2O2 3 to pasted zinc oxide electrodes has been evaluated using chronopotentiometry, cyclic voltammetry, polarization measurements and scanning electron microscopy.

106 citations


Journal ArticleDOI
TL;DR: In this paper, the anodic intercalation of the anions HSO−4, ClO−4 and BF−4 into natural graphite (as composite electrodes with polypropylene binder) and its cathodic redissolution is presented.

Journal ArticleDOI
TL;DR: In this article, the authors described the characteristics and elaboration of polyphenylene oxide films bearing reactive amino functions by the selective electrochemical oxidation of phenol derivatives substituted by amino or anilino groups.

Journal ArticleDOI
TL;DR: In this article, the electrochemical behavior of manganese(II) phthalocyanine dissolved in pyridine, dimethylsulfoxide, or dimethylacetamide is reported, in the presence of perchlorate, chloride, and bromide supporting electrolyte anions.
Abstract: : The electrochemical behaviour of manganese(II) phthalocyanine dissolved in pyridine, dimethylsulfoxide, or dimethylacetamide is reported, in the presence of perchlorate, chloride, and bromide supporting electrolyte anions. Electron transfer couples representing net oxidation of manganese, and of the phthalocyanine ring, and two net reductions of the phthalocyanine ring are characterised by a range of electrochemical techniques, with emphasis on cyclic voltammetry. Heterogeneous rate constants are reported for several of these couples in the presence of perchlorate ion. All the couples show close to ideal reversible behaviour except at higher scan rates for chloride and bromide as supporting electrolyte anions, where some deviation is observed. This system does not exhibit such sensitivity to environment as was previously observed with iron phthalocyanine. (Author)

Journal ArticleDOI
TL;DR: In this article, the authors investigated the redox stability domain of polymer solid electrolytes (polyther-salt complexes) using cyclic voltammetry and found that the macromolecular backbone was remarkably inert, and the stability range was mainly limited by the anion of the dissolved salt.

Journal ArticleDOI
TL;DR: In this paper, the anodic oxidation of 1-naphthylamine (ArNH 2 ) was studied at the platinum electrode in acetonitrile by controlled potential electrolysis, chronopotentiometry, cyclic voltammetry and spectrometric methods.


Journal ArticleDOI
TL;DR: In this article, cyclic voltammetry and potentiostatic coulometry were used to study the electrochemical oxidation of thiourea in aqueous solutions of nitric acid, ammonium nitrate and ammonium hydroxide and in acetonitrile.

Journal ArticleDOI
01 Dec 1981
TL;DR: In this article, a quantitative description of nonlinear mass transport to microdisk electrodes can be achieved with the aid of a two-dimensional simulation based on an implicit difference approximation The agreement with experimental data is very close The reversible and the quasi-reversible charge transfer is discussed to facilitate the interpretation of cyclic voltammograms, working-curves and diagnostic criteria.
Abstract: The cyclic voltammetric response, which is obtained by measurements at microdisk electrodes (R ± 1 mm), may deviate strongly from theoretical predictions The cause of such effects is due to nonlinear diffusion processes, which, in principle, are present at unshielded disk electrodes They increase with diminishing electrode radii and slow scan rates in accordance with the value of the dimensionless parameter = (D/aR2)1/2 A quantitative description of nonlinear mass transport to microdisk electrodes can be achieved with the aid of a two-dimensional simulation based on an implicit difference approximation The agreement with experimental data is very close The reversible and the quasi-reversible charge transfer is discussed To facilitate the interpretation of cyclic voltammograms, working-curves and diagnostic criteria are presented


Journal ArticleDOI
TL;DR: In this article, the reduction of water by methyl viologen, catalyzed by colloidal platinum, has been extensively studied as a function of pH, radical concentration, and platinum concentration by several independent techniques.
Abstract: The reduction of water by methyl viologen, catalyzed by colloidal platinum, has been extensively studied as a function of pH, radical concentration, and platinum concentration by several independent techniques. The data present a comparative test of a homogeneous kinetic approach and a novel electrochemical approach. Two techniques were used to monitor the platinum-catalyzed oxidation of methyl viologen radical: conventional and stopped flow mixing experiments, and a novel application of electrocatalytic cyclic voltammetry. Conventional kinetic analysis for homogeneous reactions provides conditional rate constants which are greater than first order in platinum. At (Pt) = 10/sup -6/ M and pH 3.0, the conditional rate constant is k = 1.2 x 10/sup 4/ L mol/sup -1/s/sup -1/. In addition, steady state catalysis of hydrogen production analogous to photochemical systems was monitored in a nonphotochemical system, using electrochemically reduced mediators. The methods are critically compared as mechanistic tools. Only data obtained with use of steady state techniques can be quantitatively analyzed by using simple electrochemical theory. The principle findings include the following: (1) a surprising apparent second order rate dependence on colloid concentration is accounted for by electrochemical theory, but not by homogeneous theory; (2) the electrochemical model quantitatively accounts for the shift inmore » pH/sub 1/2/ with mediator concentration; and (3) with use of an electrogenerated mediator an experimental value for log j/sub H2//sup 0/ = -3.4 is obtained for colloidal platinum, in good agreement with the bulk electrode.« less

Journal ArticleDOI
TL;DR: In this paper, cyclic voltammetry and polarography were used to investigate the oxidation of cobalt sandwich complexes with cyclic diolefine and cyclobutadiene ligands.

Journal ArticleDOI
TL;DR: In this paper, the photovoltage of single crystal, n-type CdTe (E sub g = 1.4 eV) has been studied with respect to barrier height, E sub B, when contacting a liquid electrolyte solution containing a fast, one-electron, outer-sphere redox reagent.
Abstract: : Single crystal, n-type CdTe (E sub g = 1.4 eV) has been studied with respect to barrier height, E sub B, when contacting a liquid electrolyte solution containing a fast, one-electron, outer-sphere redox reagent. We approximate E sub B as equal to the photovoltage measured by cyclic voltammetry of various redox couples at illuminated n-CdTe vs. a reversible electrode. N-CdTe surfaces pretreated with an oxidizing etch give an E sub B of approximately 0.5 V + or - 0.1 V in H2O/0.1 M NaClO4 or CH3CN/0.1 M (n-Bu4N)ClO4 that is independent of the E sub 1/2 of the added redox couple. A reducing etch pretreatment gives an E sub B in either of the electrolyte solutions that depends on E sub 1/2 of the redox couple in a manner consistent with a nearly ideal semiconductor. The reduced CdTe exhibits an E sub B of up to 0.9 V for a redox couple having E sub 1/2 near 0.0V vs. SCE, whereas couples having E sub 1/2 negative of approx. -1.0 V vs. SCE give zero photovoltage. Auger and X-ray photoelectron spectroscopy of the reduced and oxidized surfaces are qualitatively different. The reduced surface exhibits signals for Cd and Te in relative intensities that are consistent with a close to stoichiometric (1/1) surface. The oxidized surface exhibits little or no detectable Cd signal and the Te signal is consistent with a thick overlayer of elemental Te.


Journal ArticleDOI
TL;DR: In this paper, cyclic voltammetry is used to study the reduction of ZrCl4 in molten NaCl, KCl-LiCl or CsCl and the nature of the various electrochemical processes.
Abstract: Cyclic voltammetry is used to study the reduction of ZrCl4 in molten NaCl, KCl-LiCl or CsCl and the nature of the various electrochemical processes. The chemical reactions between Zr metal and the M2ZrCl6 complex occurring in the bath are also studied.

Journal ArticleDOI
TL;DR: In this article, the derivative peak current ratio was used for the measurement of rate constants of reactions coupled to charge transfer in N,N-dimethylformamide and phenol.

Journal ArticleDOI
TL;DR: In this article, the deposition of zinc on silver from alkaline zincate solutions has been investigated using cyclic voltammetry, potential pulse methods, x-ray diffraction, and scanning electron microscopy.
Abstract: The deposition of zinc on silver from alkaline zincate solutions has been investigated using cyclic voltammetry, potential pulse methods, x‐ray diffraction, and scanning electron microscopy. Approximately one monolayer of zinc is formed in the underpotential deposition region prior to bulk deposition. The underpotential shift is 0.15V. Zinc forms at least two alloys with the substrate. One was identified as and the other as the β' phase of. The bulk zinc deposit consists of hexagonal platelets that are oriented both parallel and perpendicular to the basal plane.

Journal ArticleDOI
TL;DR: In this article, the growth and decay of surface enhanced Raman scattering (SERS) from cyanide complexes adsorbed on a Cu electrode have been measured with an optical multichannel analyzer during an electrochemical oxidation-reduction cycle.

Journal ArticleDOI
TL;DR: In this article, the correlation of peak potential and peak current data is suggested by the following equation: ΔEp=ΔErealp+IpRPu, which is derived from the intercepts.

Journal ArticleDOI
T Mahmood1
TL;DR: In this paper, the authors used temperature-programmed reduction (TPR) and cyclic voltammetry to investigate Pt and Ru dispersed catalysts unsupported and supported on conducting carbon at various stages of the catalyst preparation.

Journal ArticleDOI
TL;DR: In this article, a linear correlation was obtained between the measured E1/2 values and the sum of Hammett parameters, Σσm, for a series of substituted complexes of (η6-arene)2CrI.