Showing papers on "Electrode potential published in 1990"
TL;DR: In this article, the equation of Faradaic admittance under potentiostatic control is derived based on the conditions of stability of steady-state for electrode processes whose rates depend upon the two state variables besides the electrode potential.
257 citations
TL;DR: In this article, surface infrared spectra in the terminal C-O stretching region are reported for various 12CO/13CO mixtures adsorbed on an ordered Pt(111) electrode in 0.1 M HClO4 as a function of CO coverage.
Abstract: Surface infrared spectra in the terminal C–O stretching region are reported for various 12CO/13CO mixtures adsorbed on an ordered Pt(111) electrode in 0.1 M HClO4 as a function of CO coverage θ (0.05≲θ≲0.6) and electrode potential E. Contributions to the coverage‐induced shift in the C–O stretching frequency νtCO arising from dynamic dipole–dipole coupling ΔνD, and from static dipole and ‘‘chemical’’ effects ΔνC, are obtained from the mixed isotope spectra. Similar to the corresponding ultrahigh vacuum (UHV) system, the former provides the largest contribution, ΔνD being 30–35 cm−1 for saturated CO layers (θ≊0.6). Substantial differences in the νtCO ‐θ (and ΔνD ‐θ) dependencies were observed for CO adlayers formed by dosing from suitably low solution concentrations (∼2×10−5 M), and from saturated irreversibly adsorbed layers by means of partial electrooxidative stripping.Using the latter ‘‘stripping’’ procedure, only small (≲5 cm−1) decreases in νtCO and ΔνD were observed as θ is decreased over the range ...
233 citations
TL;DR: In this paper, a unifying derivation of the various concepts of "absolute" electrode potential is provided starting from a simple electrochemical cell and it is shown that all kinds of absolute potential are implicit in the thermodynamics of the cell and all have the same conceptual validity.
138 citations
TL;DR: In this paper, a kinetic model consistent with the observed dissolution behavior was proposed, and the key feature of the model is its branched nature, defining the various possible reaction pathways available to certain intermediates.
115 citations
TL;DR: In this paper, the corrosion inhibition mechanism of benzotriazole and 4-hydroxybenzotitriazole for copper in sulphate solutions was investigated by SERS spectroscopy and impedance measurements.
107 citations
TL;DR: In this article, dodecylsulphate was incorporated into polypyrrole matrix during anodic polymerization of pyrrole, and the concentration was adjusted such that in the oxidized film about one half of the polypryrole cationic groups was charge compensated by the sulphate groups from the incorporated dodecyclosophate, the second half by anions from the electrolyte.
101 citations
TL;DR: In this paper, the pyridine adsorption on Au(110) and Au(100) surfaces has been characterized using chronocoulometry, showing that the maximum surface excess is equal to 6.1 × 10−10 mol cm−2, and the Gibbs energy at the potential of maximum adaption is −42 kJ mol−1.
76 citations
TL;DR: In this article, the dependence of the electrocatalytic activity of Raney nickel on the prepolarization conditions was studied using the impedance spectra in the frequency range 1 mHzf 10 kHz to determine the characteristic pore parameters and identify the kinetic behaviour of the porous electrodes by application of transfer function analysis using nonlinear fit routines.
Abstract: Electrochemical d.c. and a.c. measurements have been carried out on porous Raney nickel in H2-saturated 0.1 M, 1 M, and 6 M NaOH solutions atT=303 K and 333 K using rotating-disc and static-plaar electrodes. For comparison, measurements were also performed on graphite-cloth and graphite-felt electrodes. From polarization curves and current transients obtained in the potential range of the hydrogen evolution and hydrogen oxidation reactions the dependence of the electrocatalytic activity of Raney nickel on the prepolarization conditions was studied. Impedance spectra in the frequency range 1 mHzf 10 kHz were used to determine the characteristic pore parameters and to identify the kinetic behaviour of the porous electrodes by application of transfer function analysis using non-linear fit routines.
74 citations
TL;DR: The importance of precise control of the potential during deposition of the more noble metal is emphasized in this article, where the authors show that Ni passivation does not occur under the conditions used to electrodeposit Ni-Cu multilayers.
Abstract: High‐quality specimens of sufficient thickness for reliable testing are needed if the enhanced properties observed for ultrastructured multilayered metals are to be understood and exploited. In the present paper, factors affecting the quality of multilayers electrodeposited from a single electrolyte, via concerted modulation of the electrode potential and electrolyte mass transport, are discussed. The importance of precise control of the potential during deposition of the more noble metal is emphasized. Results obtained by a pulse technique show that Ni passivation does not occur under the conditions used to electrodeposit Ni‐Cu multilayers. Attainable deposit quality is illustrated by tensile test data for a series of 90%Ni‐10%Cu specimens that are twice as strong as Ni and for which the standard deviations for the ultimate tensile strength and modulus are only 1.5 and 3.9%, respectively.
67 citations
TL;DR: In this article, the oxide growth kinetics of thin oxide films of zirconium were investigated as a function of the electrode potential, the potential sweep rate and the pH in phosphate electrolytes.
Abstract: Potentiodynamically grown thin oxide films of zirconium were investigated as a function of the electrode potential, the potential sweep rate and the pH in phosphate electrolytes. The oxides were characterized by coulometric and impedance measurements in the frequency range . The rate of oxide growth changes with the sweep rate according to the high field law. The oxide growth kinetics depends on the pH of the forming electrolyte. The results are interpreted in terms of anion incorporation into the film. The system impedance is characterized by a low‐frequency capacitive behavior associated with the oxide film and by a high‐frequency resistive behavior corresponding to the electrolyte. The oxide capacity was found to be frequency dependent. The oxide impedance can be interpreted in terms of a dielectric relaxation model. A complex dielectric constant was calculated at pH 14.
63 citations
TL;DR: In this paper, surface electrochemical studies of 2-pyridinethiol (2PyT, 2-mercaptopyridine) and 4-polytopeptopepto-tetramer (4-MCT) at Ag(111) single-crystal electrode surfaces in aqueous fluoride solutions are reported.
TL;DR: The ennoblement of the electrode potential is caused not by the metabolism but by the metabolite of the sea diatoms included in the thin organic film under the slime layer as mentioned in this paper.
TL;DR: In this paper, a systematic study of the impedance behavior of the anodic niobium oxide film/aqueous electrolyte interface was carried out using the lock-in technique at different signal frequencies.
TL;DR: In this article, a study of two different types of micro reference electrodes with respect to electrochemical performance, stability, and whole wafer processing compatibility is presented, and theoretical calculations and electrochemical measurements are used to correlate the electrolyte leakage, electrode potential drift and electrode impedance with each other.
Abstract: In this paper we present a study of two different types of micro reference electrodes with respect to electrochemical performance, stability and whole wafer processing compatibility. The first reference electrode consists of an already reported porous silicon membrane as quasi open liquid junction, a micro-machined cavity in the silicon substrate filled with a KCl solution and a Ag/AgCl wire which is in contact with this solution. It exhibits promising results with respect to stability and lifetime due to the very small pores. However, a sufficient uniformity over the wafer requires a particular care due to the critical control of the electrochemical HF etching procedure. The second reference electrode is a less complicated design but involves special requirements on the internal electrolyte. In this structure, an anisotropically etched cavity is made through the wafer, thus contacting the solutions at both sides. The efflux of the internal electrolyte is in this case limited partly by the small opening at one side of the wafer, and by the incorporation of the internal electrolyte in a hydrogel, which strongly reduces its diffusion. Theoretical calculations and electrochemical measurements are used to correlate the electrolyte leakage, electrode potential drift and electrode impedance with each other. With the reduction of the diffusion coefficient of the inner electrolyte ions in the hydrogel, sufficient stability can be obtained. Our results indicate that an integrated reference electrode with an internal volume of 0.1 μl and with a drift of less than 10 μV/h is feasible. The technologies of these two designs are compared in terms of process compatibility and electrochemical behavior.
TL;DR: In this article, the effect of electrode potentials on the external reflection spectra of ionic species in solution is discussed, and the results for ClO4− and HSO4−/SO42− demonstrate that within the thin layer of solution between the electrode and IR window, important concentration and pH changes occur.
TL;DR: In this article, the authors investigated the electroadsorption of sulphide species on gold and the growth of sulphur multilayers using optical and electrochemical techniques in sodium tetraborate buffer as the supporting electrolyte (pH 7.0 and 9.2).
TL;DR: In this paper, the authors used the radioactive labeling method to study the adsorption of bisulfate/bisulfate anions on a smooth gold electrode and found that the surface attachment occurs mainly through electrostatic interactions between the surface and the ions.
TL;DR: In situ Raman spectroscopy showed that ion transport in polypyrrole thin films doped with copper phthalocyanine tetrasulfonate is carried out by small cations from the supporting electrolytes during the redox reaction as discussed by the authors.
Abstract: : Cyclic voltammetry has shown that polypyrrole thin films doped with copper phthalocyanine tetrasulfonate are electrochemically conducting in the negative potential range where polypyrrole (PPy) in the PPy-CuPcTs film exists as a neutral form. In situ Raman spectroscopy showed that ion transport in the PPy-CuPcTs film was carried out by small cations from the supporting electrolytes during the redox reaction of the PPy. Majority of the CuPcTs of the original doping level still remains in the film after the reduction of the PPy. Large cations, such as tetrabutylammonium and methyl viologen, showed strong effects on shifting the redox potential of the PPy thin film electrodes. A very strong resonance Raman band, which is due to the symmetric stretching of the C=C bond in the neutral form of PPy, disappeared when a PPy thin film electrode was oxidized. Redox potentials of several PPy thin films formed with different anions were calculated by monitoring the intensity change of the Raman band when the electrode potential was changed. The redox potentials obtained by this method are very close to those by cyclic voltammetry.
TL;DR: In this article, les produits de reduction de methylviologene MV 2+ sur une electrode d'argent est etudiee par spectrometrie SERS afin d'examiner les differentes interactions d'adsorption
Abstract: L'adsorption des produits de reduction de methylviologene MV 2+ sur une electrode d'argent est etudiee par spectrometrie SERS afin d'examiner les differentes interactions d'adsorption
TL;DR: In this paper, the steady-state faradaic current at a microdisk electrode tip is measured as the tip is scanned close to a surface, where the tip response depends upon the nature of the polymer, the substrate electrode potential, the identity of the solution redox species, and the tip potential.
Abstract: Scanning electrochemical microscopy (SECM) in the feedback mode, where the steady-state faradaic current at a microdisk electrode tip is measured as the tip is scanned close to a surface, was used to investigate several different polymer films on electrode surfaces: poly(vinylferrocene), N,N{prime}-bis(3-(trimethoxysilyl)propyl)-4,4{prime}-bipyridinium dibromide, and Naflon containing Os(bpy){sub 3}{sup 2+} The tip response (ie, positive or negative feedback) depends upon the nature of the polymer, the substrate electrode potential, the identity of the solution redox species, and the tip potential Studies carried out with polymer films on interdigitated array (IDA) electrodes with different redox species in the cell solution demonstrate that the SECM images can be used to distinguish chemically different sites on a substrate surface It was also possible with similar methods to distinguish Au and oxide-covered Cr electrodes in an IDA
TL;DR: In this paper, the steady-state behavior and impedance of zinc electrodes have been analyzed under potentiostatic control in highly acidic sulphate electrolytes used for zinc electrowinning, and it is shown that zinc deposition takes place under conditions where hydrogen evolution remains passivated on the deposit surface.
Abstract: In highly acidic sulphate electrolytes used for zinc electrowinning, the steady-state behaviour and the impedance of zinc electrodes have been analyzed under potentiostatic control. It is shown that zinc deposition takes place under conditions where hydrogen evolution remains passivated on the deposit surface. A depassivation of hydrogen evolution leading to the deposit corrosion can be provoked by an electrode excursion near the corrosion potential. The presence of nickel impurities facilitates this depassivation process even though the electrode potential remains cathodic. The depassivation becomes easier with the existence of a scratch on the substrate surface, because of bubbles retained on this defect.
IBM1
TL;DR: In this paper, a better understanding of the geometry of adsorbed bisulfate species on the surface is gained by monitoring simultaneously more than one vibrational mode of the molecule.
TL;DR: In this paper, a surface preparation technique of well-ordered single crystal palladium electrodes was established by using iodine-coating and anneal-quenching of the electrodes.
TL;DR: The surface chemistry of Cu (100) in HCl solutions has been examined by Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and Auger depth profiling (ADP).
TL;DR: In this article, the theoretical potential distribution within a flow-by-parallel-pipedic porous electrode operating in limiting current conditions in a two-compartment electrolytic cell was analyzed.
Abstract: This paper deals with the theoretical potential distribution within a flow-by parallelepipedic porous electrode operating in limiting current conditions in a two-compartment electrolytic cell. The model takes into account the influence of the counter-electrode polarization and of the separator ohmic resistance. The results show that the design of the porous electrode requires the knowledge of the solution potential distribution within the whole cell volume.
TL;DR: In this paper, it was shown that the extent of anion sorption is a function of the potential of the electrode on which polyaniline is deposited, the direction of potential shift and the solution pH.
TL;DR: In this paper, the kinetics of the electroreduction of Zn2+ have been studied in DMSO in the presence of different concentrations of tetraethylammonium and tetrabutylaminonium perchlorates (TEAP and TBAP) using cyclic voltammetry and chronoamperometry.
TL;DR: In this article, a two-dimensional mathematical model of the Zn-ZnO porous electrode has been developed, which calculates electrode and electrolyte potentials, current density distribution, electrolyte concentrations, and Zn and ZNO distributions.
Abstract: A two-dimensional mathematical model of the Zn-ZnO porous electrode has been developed. The model calculates electrode and electrolyte potentials, current density distribution, electrolyte concentrations, and Zn and ZnO distributions. The primary assumptions are a uniform-composition counterelectrode, a constant potential along the boundary separating the Zn-ZnO electrode from the counterelectrode, no convective flow, and an infinite electronic-matrix conductivity. The model predicts movement of the active material from the center of the electrode toward the edge of the electrode.
TL;DR: L'adsorption de methanol sur une electrode de noir de platine est examinee in situ par spectrometrie RMN au 13 C as mentioned in this paper.
Abstract: L'adsorption de methanol sur une electrode de noir de platine est examinee in situ par spectrometrie RMN au 13 C