Showing papers on "Supporting electrolyte published in 2005"
TL;DR: Titanium oxide nanotubes were successfully grown from a titanium plate by direct anodic oxidation with 0.2 wt % hydrofluoric acid being the supporting electrolyte and look like honeywell with the structure similar to that of porous alumina obtained by the same technique.
Abstract: Titanium oxide nanotubes were successfully grown from a titanium plate by direct anodic oxidation with 0.2 wt % hydrofluoric acid being the supporting electrolyte. These nanotubes are of uniform size and are well-aligned into high-density arrays. They look like honeywell with the structure similar to that of porous alumina obtained by the same technique. TiO2 anatase phase was identified by X-ray diffraction. Significant blue-shift in the spectrum of UV−vis absorption was observed. The mechanism of the novel, simple, and direct growth of the nanotubes was postulated. To investigate their potentials in environmental applications, degradation of pentachlorophenol (PCP) in aqueous solution was carried out using photoelectrocatalytic (PEC) processes, comparing with electrochemical process (EP) and photocatalytic (PC). A significant photoelectrochemical synergetic effect was observed. The kinetic constant of PEC degradation of PCP using TiO2 nanotubes electrode was 86.5% higher than that using TiO2 film electr...
423 citations
TL;DR: In this article, four kinds of activated carbons with specific surface area of ca. 1050m2g−1 were fabricated from fir wood and pistachio shell by means of steam activation or chemical activation with KOH.
213 citations
TL;DR: X-ray photoelectron spectroscopy and electrochemical results indicate that the water-miscible ILs used in this study can interact with the GC electrode and form molecular films on the electrode surface, and these formed molecular films are found to possess striking electrochemical properties.
Abstract: This letter describes the formation and possible electrochemical applications of molecular films of water-miscible imidazolium-based ionic liquids (ILs) on glassy carbon (GC) electrodes. X-ray photoelectron spectroscopy (XPS) and electrochemical results indicate that the water-miscible ILs used in this study can interact with the GC electrode and form molecular films on the electrode surface. The formed molecular films are found to possess striking electrochemical properties such as electrocatalysis toward ascorbic acid (AA) and the capability to facilitate direct electron transfer of horseradish peroxidase (HRP). This demonstration would pave the way for new electrochemical applications of water-miscible ILs and is envisaged to be useful for the investigation of the electrochemical properties of water-miscible ILs in aqueous media provided the same counteranion is used as the supporting electrolyte.
136 citations
TL;DR: In this paper, both imidazolium and pyrrolidinium-based ionic liquids were used to assess the influence of the nature of the ionic liquid on the morphology and electrochemical activity of the conducting polymers.
131 citations
TL;DR: In this paper, the effect of operating parameters such as initial pH, supporting electrolyte concentration, phenol concentration, and charge input was studied using Box-Behnken second order composite experimental design.
Abstract: Electrochemical oxidation of phenol using a Ti/TiO2-RuO2-IrO2 anode in the presence of chloride as the supporting electrolyte was investigated. The experiments were performed in an undivided batch reactor. Preliminary investigations showed that only a small fraction of phenol was oxidized by direct electrolysis, while complete degradation of phenol was achieved by indirect electrochemical oxidation using chloride as a supporting electrolyte. The effect of operating parameters such as initial pH, supporting electrolyte concentration, phenol concentration, and charge input was studied using Box-Behnken second order composite experimental design. The effect of current density on COD removal was studied separately. TOC removal and AOX formation were studied for selected conditions. It was found that the formation of chlorinated organic compounds was pronounced at the beginning of electrolysis, but it was reduced to lower levels by extended electrolysis.
130 citations
TL;DR: The results showed to have a high effectiveness of the electrocoagulation method in removing boron from aqueous solutions, with the highest borons removal efficiency, 97%, was found by CaCl2.
130 citations
TL;DR: Anodic methoxylation of several organic compounds has been successfully achieved in the absence of intentionally added supporting electrolyte using an electrochemical microflow system.
121 citations
TL;DR: In this paper, an in situ plated lead film electrode was proposed for adsorptive stripping voltammetric determination of nickel and cobalt in the presence of dimethylglyoxime.
102 citations
TL;DR: In this paper, a femtosecond broad-band multiplex spectroscopy setup with a polycrystalline Pt electrode with both CO-free and CO-saturated electrolytes was used for simultaneous electrochemical and vibrational sum-frequency generation.
96 citations
TL;DR: In this article, a self-supported paired electro-synthesis of 2,5-dimethoxy-2,5dihydrofuran was proposed, where the anode and cathode were placed directly facing each other and without intentionally added electrolyte.
84 citations
TL;DR: In this paper, a simple and general strategy, namely in situ electropolymerization by using an ionic surfactant as the electrolyte, for alignment of disordered CNTs within conducting polymer/carbon nanotube composite films was demonstrated.
TL;DR: In this article, the color removal and chemical oxygen demand (COD) reduction of vat textile dye (CI Vat Blue 1: indigo) from its aqueous solution by electrochemical oxidation was performed in a batch-type divided electrolytic cell under constant potential.
Abstract: Electrochemical methods are being used increasingly as an alternative treatment process for the remediation of textile wastewaters. This study focused mainly on the colour removal and chemical oxygen demand (COD) reduction of vat textile dye (CI Vat Blue 1: indigo) from its aqueous solution by electrochemical oxidation. The process was carried out in a batch-type divided electrolytic cell under constant potential using a Pt cage as anode and Pt foil as cathode. Operating variables such as supporting electrolyte, pH, ultrasonification and treatment time were investigated to probe their effects on the efficiency of the electrochemical treatment. Colour removal was estimated by monitoring the disappearance of the absorbance peak at 681.5 nm. It was found that in acidic conditions the electrolysis was more efficient. At pH 1, an NaCl concentration of 0.24 mol dm−3, a dyeing solution concentration of 0.1% (w/v) and a period of 90 min of electrolysis, there was almost 100% colour removal and 60% reduction in COD. Voltammetric and IR investigations demonstrated that partial degradation of dye was achieved. The experimental results indicate that this electrochemical method could effectively be used as a pretreatment stage before conventional treatment. Copyright © 2005 Society of Chemical Industry
TL;DR: The most appropriate conditions for growing Pt nanoparticles on HOPG with narrow size distribution are to use an H2PtCl6 solution with HCl as supporting electrolyte and to apply a high cathodic overpotential.
Abstract: The electrochemical deposition of Pt on highly oriented pyrolytic graphite (HOPG) from H2PtCl6 solutions was investigated by cyclic voltammetry and chronoamperometry The effects of deposition overpotential, H2PtCl6 concentration, supporting electrolyte, and anion additions on the deposition process were evaluated Addition of chloride inhibits Pt deposition due to adsorption on the substrate and blocking of reduction sites, while SO42- and ClO4- slightly promote Pt reduction By comparing potentiostatic current−time transients with the Scharifker-Hills model, a transition from progressive to instantaneous nucleation was observed when increasing the deposition overpotential Following addition of chloride anions the fit of experimental transients with the instantaneous nucleation mode improves, while the addition of SO42- induces only small changes Chloride anions strongly inhibit the reduction process, which is shifted in the cathodic direction The above results indicate that the most appropriate condi
TL;DR: In acid solutions the frequency-tuning rate as well as the potential-dependent bandwidth deviates from expected linear relationships, interpreted in terms of compression/dissipation of CO islands during the CO oxidation, engendered by competitive adsorption between inactive anions from a supporting electrolyte and the reactive OH species.
Abstract: Vibrational properties of CO have been studied on Pt(111) in acid and alkaline electrolytes by synchronous measurements of CO oxidation current (0.5 mV/s) and IRAS spectra (one spectrum for every 1 mV). We found that in acid solutions the frequency-tuning rate (dνCO/dE) as well as the potential-dependent bandwidth (dΔν1/2/dE) deviates from expected linear relationships. This unusual potential-dependent behavior is interpreted in terms of compression/dissipation of CO islands during the CO oxidation, engendered by competitive adsorption between inactive anions from a supporting electrolyte and the reactive OH species.
TL;DR: In this paper, the operation of a photoelectrolyser fitted with a semitransparent semiconducting WO3 film photoanode is described, and experiments conducted under simulated AM 1.5 solar illumination demonstrated efficient photodegradation of a variety of organic chemicals including small organic molecules including EDTA and anthraquinonic Acid Blue 80 dye.
Abstract: Operation of a photoelectrolyser fitted with a semitransparent semiconducting WO3 film photoanode is described. Due to its band-gap energy of 2.5 eV, the photoresponse of the WO3 electrode extends into the blue part of the visible spectrum up to 500 nm. The WO3 photoanode exhibits particularly high incident photon-to-current efficiencies for the oxidation of several organic species with the maximum occurring at ca. 400 nm. Experiments conducted under simulated AM 1.5 solar illumination demonstrated efficient photodegradation of a variety of organic chemicals including small organic molecules as well as EDTA and anthraquinonic Acid Blue 80 dye. Although, due to the inherent mass transport limitations, the described device appears best suited to the treatment of industrial wastewater containing from 100 ppm to few g L−1 of impurities, almost complete removal of organic carbon was observed in several photoelectrolysis runs. This is apparently associated with the concomitant photooxidation of sulphate-based supporting electrolyte resulting in the formation of a powerful chemical oxidant-persulphate.
TL;DR: HNOads is suggested to be the intermediate appearing both in HAM reduction/oxidation and in NOads reduction, in agreement with the trend observed under UHV conditions.
Abstract: The mechanism of electrocatalytic reduction of nitric oxide on Pt(100)-(1 x 1) in acidic media has been studied using voltammetry, in-situ infrared spectroscopy, and on-line mass spectroscopy, considering the effect of surface defects, NO coverage, and the nature of the supporting electrolyte (sulfate vs perchlorate). Related mechanistic aspects of hydroxylamine (HAM) transformations on the same surface have been also examined. The adsorption of nitric oxide on Pt(100) results in the formation of an adlayer with a structure similar to that formed under ultrahigh vacuum (UHV) conditions. Ammonia was shown to be the main product of NOads reduction on Pt(100). The saturation coverage of NO adsorbate on Pt(100) was found to be around 0.5 ML, in agreement with previous UHV and electrochemical studies. Two features observed in the voltammetric profile for the electrocatalytic reduction of saturated and subsaturated NO adlayers were tentatively ascribed to reactions of NO species having different reactivity. The Tafel slope analysis of these voltammetric features gives values of ca. 60 mV decade(-1). This value was interpreted in terms of an EC mechanism, in which the first electron/proton transfer is at equilibrium, resulted in formation of HNOads intermediate, while the second reaction step is a chemical rate-determining step. This chemical step is assumed to involve the N-O bond breaking in HNOads intermediate, which most probably requires a free neighboring site. From a comparison with NOads reduction on Pt(111) and Pt(110), it follows that (i) the reaction mechanism is structure sensitive and (ii) Pt(100) is the most active surface for breaking the N-O bond, which is in agreement with the trend observed under UHV conditions. As suggested in our previous studies, the electrocatalytic reduction of HAM is likely to proceed through its partial dehydrogenation. In this study, we further develop this idea, and, based on the mechanism for NOads reduction proposed here, we suggest HNOads to be the intermediate appearing both in HAM reduction/oxidation and in NOads reduction.
TL;DR: Characterization by NMR and CD spectroscopy in solution and by ESI-FT-ICR mass spectrometry in the gas phase suggests that an equilibrium exists in water/methanol of a major 2:2 complex and a minor 3:3 complex of ligands and metal corners.
Abstract: Chiral, enantiopure metallo-supramolecular rhombs self-assemble in solution through coordination of bis-pyridyl-substituted ligands with (en)M(NO3)2 (en = ethylenediamine, M = PdII, PtII). Characterization by NMR and CD spectroscopy in solution and by ESI-FT-ICR mass spectrometry in the gas phase suggests that an equilibrium exists in water/methanol of a major 2:2 complex and a minor 3:3 complex of ligands and metal corners. In the gas phase, doubly charged 2:2 complexes fragment into two identical singly charged halves followed by metal-mediated C−H and C−C bond activation reactions within the ethylenediamine ligands. Electrochemical scanning tunneling microscopy (EC-STM) provides in situ imaging of the complexes even with submolecular resolution. Flat-lying rhombs are deposited under potential control from an aqueous electrolyte on a Cu(100) electrode surface precovered by a tetragonal pattern of chloride anions from the supporting electrolyte. Chirality induces the formation of only one domain orientat...
TL;DR: In this article, the influence of cetyltrimethylammonium bromide (CTAB) on the electrochemical behavior of bisphenol A at the carbon paste electrode (CPE) was investigated.
Abstract: The influence of cetyltrimethylammonium bromide (CTAB) on the electrochemical behavior of bisphenol A at the carbon paste electrode (CPE) was investigated. CTAB, with a hydrophobic C-H chain, can adsorb at the CPE surfacevia hydrophobic interaction and then change the electrode/solution interface, and finally affects the electrochemical response of bisphenol A, confirming from the remarkable oxidation peak current enhancement. The electrode process of bisphenol A was examined, and then all the experimental parameters which affects the electrochemical response of bisphenol A, such as pH value of the supporting electrolyte, accumulation potential and time, potential scan rate and the concentration of CTAB, were examined. Finally, a sensitive and simple voltammetric method was developed for the determination of bisphenol A. Under the optimum conditions, the oxidation peak current of bisphenol A varied linearly with its concentration over the range from 2.5 x 10 - 8 to 1 x 10 - 6 mol/L, and the detection limit was found to be 7.5 x 10 - 9 mol/L. This method was successfully employed to determine bisphenol A in some waste plastic samples.
TL;DR: Comparison of the experimental results of the chemical oxygen demand (COD) removal versus charge indicated that the order of decreasing COD removal for various phenolic compounds as catechol > resorcinol > m-cresol > o-c Resol > phenol > p-cResol is as follows:.
Abstract: Electrochemical degradation of mixed phenolic compounds present in coal conversion wastewater was investigated in the presence of chloride as supporting electrolyte. Initially, the degradation expe...
TL;DR: The copolymerization of indole and 3,4-ethylenedioxythiophene (EDOT) was achieved electrochemically in acetonitrile containing lithium perchlorate as supporting electrolyte by direct anodic oxidation of the monomer mixtures on platinum and stainless steel electrodes as mentioned in this paper.
Abstract: The copolymerization of indole and 3,4-ethylenedioxythiophene (EDOT) was achieved electrochemically in acetonitrile containing lithium perchlorate as supporting electrolyte by direct anodic oxidation of the monomer mixtures on platinum and stainless steel electrodes. As-formed copolymers own both the advantages of polyindole (PIn) and poly (3,4-ethylenedioxythiophene) (PEDOT), i.e., good thermal stability, good electrochemical behavior, high conductivity and excellent ambient stability. The structure and morphology of the copolymer were investigated by UV-vis, infrared spectroscopy, thermal analysis and scanning electron microscopy (SEM), respectively.
TL;DR: In this article, conditions for electrochemical deposition of Prussian blue (PB) from a single ferricyanide solution on the gold electrode surface are discussed and the experimental results show that only in the presence of KCl salt, the electrodeposition of PB can be obtained easily.
TL;DR: In this article, a comparative study of charge transfer at electrodes modified with the title polymer films was performed mainly in 1M perchlorate solutions at variable pH by using different electrochemical methods.
TL;DR: In this paper, the influence of electric potential, flow velocity and supporting electrolyte on the reaction rate, current efficiency and energy consumption was investigated for bare RVC and polyaniline-covered RVC.
Abstract: Reduction of highly toxic hexavalent chromium (Cr(VI)) to its trivalent state (Cr(III)) is necessary to enable further treatment of wastewater by precipitation or adsorption. For this purpose, the present study proposes the use of thin polyaniline films deposited on a large surface area substrate reticulated vitreous carbon (RVC). The influence of electric potential, flow velocity and supporting electrolyte on the reaction rate, current efficiency and energy consumption was investigated for bare RVC and polyaniline-covered RVC. The film stability was also evaluated. The polyaniline thickness was not observed to influence the reaction rate. Also, the synthesis conditions must be controlled in order to guarantee that the substrate surface is completely covered by the polymer. The supporting electrolyte was observed to influence the energy consumption, but not the reaction rate. Flow velocity is very important for process optimization since it improves the mass transfer. Finally, the polyaniline-modified electrode is a promising material for use in Cr(VI) reduction as it remained stable after several cycles and no loss in the reduction rate was observed.
TL;DR: Comparison between the direct electroreduction of aryldiazonium compounds on a platinum electrode and their reaction with [Pt2-, Na+, NaI] suggests that a similar general mechanism is responsible for the grafting.
Abstract: Platinum phases of general formula [Pt(n-), M+, MX] can be electrogenerated from cathodic polarization in dry dimethylformamide containing a supporting electrolyte, MX. The reaction of these electrogenerated Pt phases as reducing agent with aryldiazonium salts was investigated for preparing controlled metal-organic interfaces and characterizing the reactivity of the "reduced platinum phases". In a two-step process, the "reduced platinum phase" locally reacts with aryldiazonium salts, leading to the attachment of aryl groups onto the metal surface in the previously modified areas. Detailed experiments using cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), and in situ electrochemical atomic force microscopy (EC-AFM) were carried out to follow the reaction in solution with the example of NaI as supporting electrolyte (MX = NaI). These studies demonstrate the irreversible attachment of aryl groups onto the platinum electrode. Comparison between the direct electroreduction of aryldiazonium compounds (4-nitrophenyl- and 4-bromophenyldiazonium) on a platinum electrode and their reaction with [Pt2-, Na+, NaI] suggests that a similar general mechanism is responsible for the grafting. However in the second case, no applied potential is required to stimulate the binding thanks to the reductive properties of [Pt2-, Na+, NaI]. Competitive reduction of the organic layer and growth of the layer were observed and analyzed as a function of the injected charge used to initially produce [Pt2-, Na+, NaI]. Similar reactions are highly probable with other MX salts owing to the redox properties observed for this type of platinum phase ([Pt(n-), M+, MX]).
TL;DR: The results obtained are interpreted quite satisfactorily in terms of the capillary membrane model recently developed by Barreira et al, thus providing additional support to its usefulness for the description of ionic transport through polyelectrolyte multilayers.
Abstract: Electrochemical impedance spectroscopy and cyclic voltammetry are employed to characterize poly(styrenesulfonate)/poly(allylamine hydrochloride) multilayers assembled onto cysteamine-modified gold surfaces. The influence of the supporting electrolyte and temperature on the impedance response is studied because of both its practical interest and the need to test further the capillary membrane model recently developed by Barreira et al. [J. Phys. Chem. B 2004, 108, 17973]. The results obtained are interpreted quite satisfactorily in terms of this model, thus providing additional support to its usefulness for the description of ionic transport through polyelectrolyte multilayers. It is observed that the nature of the supporting electrolyte affects the film resistance and the electrode coverage. The temperature dependence of the diffusion coefficient is shown to follow the Arrhenius law, and the activation energy is estimated as 61 kJ/mol. Experiments with a large number of layers are also included to show th...
TL;DR: A novel electrolytic system using solid-supported bases for in situ generation of a supporting electrolyte from methanol as a solvent to provide the alpha-methoxylated product in good to excellent yields is developed.
Abstract: We have successfully developed a novel electrolytic system using solid-supported bases for in situ generation of a supporting electrolyte from methanol as a solvent. Anodic methoxylation of phenyl 2,2,2-trifluoroethyl sulfide using solid-supported bases was carried out to provide the α-methoxylated product in good to excellent yields. The α-methoxylated product and solid-supported bases were easily separated by only filtration, and the separated solid-supported bases were recyclable. Anodic methoxylation of phenyl 2,2,2-trifluoroethyl sulfide was successfully carried out 10 times by the recycling of silica gel-supported piperidine in good yields.
TL;DR: In this paper, the electrochemical reduction of 4-nitrobenzylbromide is studied in N,N-dimethylformamide solution in the presence and in the absence of intentionally added supporting electrolyte.
TL;DR: In this paper, the electrooxidation of naproxen was studied using boron-doped diamond (BDD) electrode by cyclic and differential pulse voltammetry (CV and DPV) in nonaqueous solvent supporting electrolyte system.
Abstract: The electrooxidation of naproxen was studied, for the first time, using boron-doped diamond (BDD) electrode by cyclic and differential pulse voltammetry (CV and DPV) in nonaqueous solvent supporting electrolyte system. The results were also compared with glassy carbon electrode (GC) under the same conditions. Naproxen undergoes one electron transfer resulting in the formation of cation radical for the first electrooxidation step, which follows other chemical and electrochemical steps such as deprotonation, removal of another electron and the attack of nucleophile (ECEC mechanism). BDD electrode provided higher signal to background ratio, well resolved and highly reproducible cyclic voltammograms than the GC electrode. With a scan rate of 50 mV s � 1 and pulse height of 50 ms, respectively, the DPV technique was able to determine the naproxen concentrations in the range of 0.5 to 50 mM with a detection limit of 30 nM. The influence of interference compounds namely 2-acetyl-6-methoxy naphthalene (AMN) on naproxen oxidation can also be followed successfully. Moreover, the percentage of AMN present in the standard chemical form of a mixture containing naproxen can be found accurately. Rapidity, precise and good selectivity were also found for the determination of naproxen in pharmaceutical formulations.
TL;DR: The standard addition method was used to determine the MCP in pure solutions, tablets and in biological fluids with satisfactory results and the interferences of some common excipients and some metal ions were studied.
TL;DR: Significant changes in the magnitude of the compact double layer component (C(COMPACT), equivalent to the Stern layer) of C(MPC) were induced by adding hydrophobic solvent components such as hexane or dodecane or by introducing Hydrophobic electrolyte ions (tetrabutyl, tetrahexyl-, and tetraoctylammonium, perchlorate, and tetraphenylborate).
Abstract: Sequential injections of single electrons (or holes) into the cores of Au140 hexanethiolate monolayer-protected clusters (MPCs) occur at measurably different electrochemical potentials owing to the extremely small (subattofarad) values of the single MPC capacitance (CMPC) of the nanoparticle. The potential increment for each sequential injection is ΔV = e/CMPC. The dependence of ΔV on the concentration of supporting electrolyte (from 1 to 100 mM), measured using square wave voltammetry, is shown to be caused, primarily, by changes in the diffuse double layer component (CDIFFUSE) of CMPC. The dependence of CDIFFUSE on rcore, the radius of the nanoparticle, is considered. Additionally, significant changes in the magnitude of the compact double layer component (CCOMPACT, equivalent to the Stern layer) of CMPC were induced by adding hydrophobic solvent components such as hexane or dodecane or by introducing hydrophobic electrolyte ions (tetrabutyl-, tetrahexyl-, and tetraoctylammonium, perchlorate, and tetrap...