Showing papers on "Supporting electrolyte published in 1993"
TL;DR: In this article, the shady state voltammetric behaviior of spherical electrodes of nanometer dimensions (1 and 10 nm) is computed by numerical solution of the Kernst-Planch and Poisson equations, showing that the reversible oxidation or reduction of an electroactive species, assumed to be present in solution at millimolar concentrations, is strongly affected by the electric field from the electrode surface, even in the presence of a large excess quantity of supporting electrolyte (0.5 M).
Abstract: The shady-state voltammetric behaviior of spherical electrodes of nanometer dimensions (1 and 10 nm) is computed by numerical solution of the Kernst-Planch and Poisson equations. The results demonstrate that the reversible oxidation or reduction of an electroactive species, assumed to be present in solution at millimolar concentrations, is strongly affected by the electric field from the electrode surface, even in the presence of a large excess quantity of supporting electrolyte (0.5 M). The assumptions of electroneutrality or diffusion-controlled transport are shown to be generally inappropriate for analyzing the voltammetric response (wave shape and limiting current) of electrodes of dimensions less than ∼0.1 μm
161 citations
TL;DR: In this article, the effect of chloride and (bi)sulfate anions in supporting acid electrolyte on the chemistry of underpotential deposition of Cu on Pt(111) and Pt(100) single crystal surfaces was studied using a combination of electrochemical and nonelectrochemical techniques.
Abstract: The effect of chloride and (bi)sulfate anions in the supporting acid electrolyte on the chemistry of underpotential deposition of Cu on Pt(111) and Pt(100) single crystal surfaces was studied using a combination of electrochemical and nonelectrochemical techniques. The presence of these anions above a threshold concentration caused a splitting in the voltammetry peaks for Cu UPD on both Pt(111) and Pt(100), with the second or split-off peak at a lower underpotential. This splitting was attributed to competition between the Cu adatoms and the adsorbed anions and the increase in thermodynamic driving force needed to displace the anions from the Pt substrate in order to form a Cu monolayer. The magnitude of the splitting appeared to be proportional to the relative strengths of the anion-Pt bonding, being larger for chloride than (bi)sulfate on either surface and being larger for the (100) surface than for the (111) surface for either anion. By the use of ex situ AES and LEED, we determined that in nearly `Cl-free` supporting electrolyte Cu appeared to be deposited at underpotential in metallic islands (or `patches`) having the Pt lattice constant (pseudomorphic growth). In the presence of Cl{sup -} the Cu was deposited at underpotentials into a Cu-Clmore » adlattice. At the Nernst potential, however, in both `Cl-free` and Cl-containing electrolyte, Cu formed a uniform metallic monolayer having the Pt lattice constant, i.e. a pseudomorphic monolayer. 34 refs., 13 figs., 3 tabs.« less
126 citations
TL;DR: In this paper, a comprehensive theory is developed that predicts the height, position and shape of a steady-state voltammetric wave, from the virtual absence of supporting electrolyte to overwhelming excess.
122 citations
TL;DR: In this article, the influence of CO2 partial pressure and the cation of the supporting electrolyte on the electrochemical reduction of CO 2 at copper electrodes in aqueous solution at 25°C was investigated.
Abstract: This paper reports a study of the influence of CO2 partial pressure and the cation of the supporting electrolyte on the electrochemical reduction of CO2 at copper electrodes in aqueous solution at 25°C. Both current efficiency (CE) and the rates of formation of the reduction products diminish linearly with decreasing CO2 pressure, while evolution of hydrogen increases. The product distribution was greatly influenced by the supporting electrolyte cation. The CE for the formation of C2H4 increased with cation in the order Cs+≈ K+ > Na+ > Li+, apparently in a manner related to the size of the cation radius. The non-metallic cation NH+
4 allowed only hydrogen evolution with a CE of about 92%.
94 citations
TL;DR: The first molal hydrolysis quotient of aluminum(III) was measured potentiometrically from 25 to 125°C at 25° intervals at ionic strengths of 0.1, 0.3, 1.0 and 5 mol · kg−1 with sodium chloride as the supporting electrolyte as mentioned in this paper.
93 citations
TL;DR: In this article, the electrochemical behavior of methyl viologen (MV ++ ) was examined in aqueous media with various supporting electrolytes (NaCl, NaBr and several tetraalkylammonium bromides) by cyclic voltammetry, chronoamperometry and chronocoulometry.
75 citations
70 citations
TL;DR: In this paper, the electroreduction of the fullerene Cm in 1,2-dichlorobenzene (ODCB) and benzonitrile (PhCN) at a Pt electrode was studied by using scanning electrochemical microscopy and fast scan cyclic voltammetry.
Abstract: The electroreduction of the fullerene Cm in 1,2-dichlorobenzene (ODCB) and benzonitrile (PhCN) at a Pt electrode was studied by using scanning electrochemical microscopy and fast scan cyclic voltammetry. The former technique was employed for steady-state measurements in a thin-layer cell formed by an ultramicroelectrode tip and mercury pool substrate. The standard heterogeneous rate constants found in both solvents, 0.46 cm/s (ODCB) and 0.12 cm/s (PhCN), appeared to be lower than one would expect for an uncomplicated outer sphere electron-transfer reaction, probably because solvation and ion pairing affect the reaction kinetics. The diffusion coefficient of c60 in ODCB depends strongly on supporting electrolyte (TBABF4) concentration. a Ag wire quasireference electrode were used in the voltammetric ex- periments.
68 citations
TL;DR: In this article, the electroactivity of polyaniline films in 0.01 mol/dm 3 HCl has been studied by probing amperometrically the variations of proton concentration at the film/solution interface.
63 citations
TL;DR: In situ AC conductimetry during electropolymerization of pyrrole is a method which allows the specific conductivity to be estimated for the polymer in statu nascendi as discussed by the authors.
62 citations
TL;DR: In this paper, the electrochemical oxidation of formic acid on Pt was studied in acidic supporting electrolyte using single-crystal electrodes, and very well-defined periodic (not chaotic) current oscillations on a stationary Pt(100) electrode were observed under both potentiodynamic and potentiostatic conditions.
Abstract: The electrochemical oxidation of formic acid on Pt was studied in acidic supporting electrolyte using single-crystal electrodes. Very well-defined periodic (not chaotic) current oscillations on a stationary Pt(100) electrode were observed under both potentiodynamic and potentiostatic conditions. The oscillatory behavior is strongly dependent on the Pt surface structure and is seen on the (100) surface but not on the (111) surface. The periodicity, the amplitude, and the absolute magnitude of the current oscillations depends on at least three variables, electrode potential and potential history, formic acid concentration, and the anion of the supporting electrolyte
TL;DR: In this article, the association of the heavy metals zinc(II) and cadmium (II) with three commercial humic acid samples has been studied by differential pulse anodic stripping voltammetry for various concentrations of supporting electrolyte.
TL;DR: In this paper, a carbon paste electrode modified by Sphagnum Sp. was used for the determination of lead(II) in natural and drinking waters by anodic stripping differential pulse voltammetry.
TL;DR: In this article, the authors investigated the effects of the presence of supporting electrolyte and the probe beam diameter on probe beam deflection experiments both theoretically and experimentally, and they showed that these concentration gradients should not be neglected.
TL;DR: In this paper, anodic stripping voltammetry of cadmium and lead in pure water, of conductivity as low as 0.6 μS, was studied at a mercury microelectrode obtained by ex situ deposition of mercury on a 10-μm radius platinum disc electrode.
TL;DR: In this paper, the electrochemical behavior of a redox-active ferrocene-modified siloxane polymer (PBF) which is capable of acting as an electron mediator for flavin enzymes was examined.
Abstract: The electrochemical behavior of a redox-active ferrocene-modified siloxane polymer (PBF) which is capable of acting as an electron mediator for flavin enzymes was examined. By cyclic voltammetry, it was revealed that the redox activity of PSF film was strongly affected by anionic species in the soaking solution. While a highly stable current response corresponding to the ferrocene/ ferricinium (Fc 0 /Fc + ) redox couple of the film was obsersed in NaClO 4 or NaBF 4 supporting electrolyte solutions, the current response gradually decreased by cycling of the potential in an aqueous solution of NaCl, NaNO 3 sodium p-toluenesulfonate, or phosphate buffer
TL;DR: In this paper, a simple model is developed to describe wave phenomena at electrode/electrolyte interfaces and the properties of the model are studied under conditions of fixed current or fixed potential, and in the absence or presence of a supporting electrolyte.
TL;DR: In this paper, steady state currents for proton reduction at a microelectrode are used to characterize the dependence of diffusion, migration, and activity in the presence of polyelectrolyte on concentration of supporting electrolyte from zero to large excess.
Abstract: Hydrogen ion is employed as the counterion to a polymer strong acid, poly(styrenesulfonate), and to a monomer analog, p-toluenesulfonate. Steady-state currents for proton reduction at a microelectrode are used to characterize the dependence of diffusion, migration, and activity in the presence of polyelectrolyte on concentration of supporting electrolyte from zero to large excess. Use of microelectrodes makes the measurements possible in the resistive dilute solutions. Measured diffusion-migration currents for proton in p-toluenesulfonate solution agree well with those predicted. Similar predictions for poly(styrenesulfonate) based on a semiempirical model agree with experimental values to within 2%
TL;DR: In this article, the potential separation between +1/0 and 0/−1 redox steps increases with decreasing solvent polarity and decreasing ionic strength of the supporting electrolyte.
TL;DR: In this paper, the authors studied the effect of convection on the concentration profiles in electrolytic cells during electrochemical deposition without a supporting electrolyte and gave theoretical evidence that convection decreases the size of the space charge on the cathodic side during fast electrolychemical deposition.
Abstract: We study the effect of convection on the concentration profiles in electrolytic cells during electrochemical deposition without a supporting electrolyte. We give theoretical evidence that convection decreases the size of the space charge on the cathodic side during fast electrochemical deposition. This effect may provide a limiting amplitude of the convective motion.
TL;DR: In this article, the partial decomposition of PF 6 - during pyrrole electropolymerization in methanol and acetonitrile on Fe and Pt electrodes was demonstrated using XPS analysis.
Abstract: The partial decomposition of PF 6 - during pyrrole electropolymerization in methanol and acetonitrile on Fe and Pt electrodes is demonstrated using XPS analysis. A complex mixture of PF 6 - , fluorides, oxyfluorides of phosphorus and metal oxides is shown to exist in the interfacial region, probably resulting in a weak cohesive layer unfavourable to the adhesion of polymer films
TL;DR: The cyclic voltammetry of benzo-15-crown-5 ether-vinyl-bipyridyl ligands, their ruthenium(II) complexes and the ‘model’ bismethoxyphenyl-vinyl-binaridyl (BVB) ligand ruthensium(III) complexes has been investigated in acetonitrile as mentioned in this paper.
Abstract: The cyclic voltammetry of benzo-15-crown-5 ether-vinyl-bipyridyl ligands, their ruthenium(II) complexes and the ‘model’ bismethoxyphenyl-vinyl-bipyridyl ligand ruthenium(II) complexes has been investigated in acetonitrile. The benzo-15-crown-5 ether units of the solution complexes are sensitive to supporting electrolyte, being more difficult to electro-oxidize on binding of sodium or magnesium cations. The tris(ligand) ruthenium(II) complexes can be reductively electropolymerized to form smooth, adherent electroactive orange films. For these electropolymerized films, the benzo-15-crown-5 ether irreversible electro-oxidation is electrocatalysed by RuIII sites and is only observed on the first cyclic voltammogram. RuIII/II redox potentials are insensitive to changes in the supporting electrolyte, apparent differences being due to variable liquid-junction potentials at the interface between the reference electrode and the supporting electrolyte solutions. Electropolymerized bismethoxyphenyl-vinyl-bipyridyl ligand ruthenium(II) complex films exhibit transparent/orange electrochromicity.
TL;DR: In this article, it was shown that methanol, ethanol, and propanol give well defined and well reproducible anodic voltammetric waves at platinum microelectrodes of radius 5-13 μm.
TL;DR: In this article, six bis(4-cyano-1,4-dihydro-4-pyridinio derivatives have been synthesized and deposited onto electrodes by cathodic electropolymerization under basic conditions.
Abstract: Six bis(4-cyano-1-pyridinio) derivatives have been synthesized and deposited onto electrodes by cathodic electropolymerization (ERed = −0.64 — −0.74 V vs. SCE) under basic conditions. The deposited films were constructed of polyviologens that showed characteristic electrochromisms with colorless or slightly yellow to blue- or red-violet. The derivative was reduced to 4-cyano-1,4-dihydro-4-pyridyl radicals, which were coupled successively to form a polyviologen film on the electrode with an elimination of cyanide ions. Characteristically, the polyviologen films deposited by this electropolymerization were insoluble in water and common organic solvents with a spontaneous cross-linking. Especially, a polyanion as a supporting electrolyte forced the polyviologen to form a polyelectrolyte complex in situ. The current efficiency of surface coverage with the polyanion electrolyte (23% in the typical case) was about four-times larger than those with monomeric anions.
TL;DR: In this article, a redox polmer film containing enzymes glucose oxidase and cellobiose oxidase was studied using potential-step chronocoulometry and cyclic voltammetry and the results were correlated with substrate response measurements made using the electrodes as amperometric biosensors.
TL;DR: In this article, it is proposed that the cations of the supporting electrolyte participate in the partial dehydration process which follows the first charge-transfer step, and the reduction of Bi(III) at a mercury electrode becomes fast and reversible.
Abstract: In highly concentrated HClO 4 (>8M) and acidic NaClO 4 (>7M) solutions the reduction of Bi(III) at a mercury electrode becomes fast and reversible. The redox kinetics depends on the electrolyte concentration and only indirectly on the water activity. It is proposed that the cations of the supporting electrolyte participate in the partial dehydration process which follows the first charge-transfer step. Hydration numbers of Bi 3+ are 8.2 in NaClO 4 and 6.9 in HClO 4 solutions
TL;DR: In this article, the anodic stripping voltammetry of copper at ex situ-formed mercury-coated carbon fiber microelectrodes was studied in the presence of low concentrations of supporting electrolyte.
TL;DR: In this paper, metal and alloys bonded on the solid polymer electrolyte (SPE) Nafion® 117 were studied as both the electrodes and electrolyte for the electrochemical reduction of pure benzaldehyde without liquid supporting electrolyte.
TL;DR: The strength of acids, their charge and possibly their behavior as polyacids can be deduced by comparing their limiting currents at a platinum ultramicroelectrode in the absence and presence of an excess of supporting electrolyte as mentioned in this paper.
TL;DR: In this paper, the reduction of the cobaltocenium cation to uncharged cobaltocene (Cc 0 ) and to cobalt anion (c - ) has been studied voltammetrically in acetonitrile in the presence and absence of supporting electrolyte using platinum microdisk electrodes of radii from 0.5 to 6 μm.
Abstract: The reduction of the cobaltocenium cation (Cc + ) to uncharged cobaltocene (Cc 0 ) and to the cobaltocenium anion (Cc - ) has been studied voltammetrically in acetonitrile in the presence and absence of supporting electrolyte using platinum microdisk electrodes of radii from 0.5 to 6 μm. In the presence of supporting electrolyte, the voltammetry is observed as two well-separated diffusion-controlled one-electron-reduction processes Cc + +e - ⇄Cc 0 and Cc 0 +e - ⇄Cc - . However, precipitation of neutral cobaltocene formed as a result of the initial one-electron-reduction process and possibly adsorption of Cc + appears to be induced by the removal of supporting electrolyte