Search results for "Supporting electrolyte"
showing 10 items of 49 documents
Boosting DMFC power output by adding sulfuric acid as a supporting electrolyte: Effect on cell performance equipped with platinum and platinum group …
2023
Direct methanol fuel cells (DMFCs) are promising electrochemical systems capable of producing electricity from the electrochemical oxidation of methanol and the reduction of oxygen. In this work, the effectiveness of the addition of sulfuric acid as a supporting electrolyte for methanol fuel composition was assessed. The results showed that the peak of power curve in DMFCs with Pt/C cathode electrocatalysts increased progressively from 70 mW cm−2 (0 mM of H2SO4) to 115 mW cm−2 with a concentration of 100 mM of H2SO4. These results underlined the positive effect of the addition of a supporting electrolyte in the methanol aqueous solution on the electrochemical output that was enhanced. Plati…
Diffusion and Migration
2003
The sections in this article are Introduction Fundamental Concepts Diffusion–migration Flux Equations Poisson Equation and the LEN Assumption Continuity Equation Ohm's Law and Migrational Transport Numbers Diffusion-conduction Flux Equation Diffusion Boundary Layer Faraday's Law and Integral Transport Numbers Nernst Equation and Concentration Overpotential Steady State Current–voltage Curves of Systems with One Active Species Integration of the Transport Equations Solutions of Homovalent Ions, |zi | =z Binary Electrolyte Solutions Ternary Electrolyte Solutions. The Supporting Electrolyte Weak Binary Electrolyte Steady State Current–overpotential Curves in the Presence of Supporting Electrol…
Studium zum Vorgang der Wasserstoffübertragung, 50. Elektroreduktion und phasentransferkatalysierte Borhydrid-reduktion prochiraler Ketone
1978
Prochirale Carbonylverbindungen wurden in die entsprechenden sekundaren Alkohole ubergefuhrt a) durch Elektroreduktion und b) mit NaBH4, in beiden Fallen mit den gleichen Ephedriniumsalzen, und zwar fur a) als optisch aktive Leitsalze und fur b) als optisch aktive Phasentransfer-Katalysatoren. Es wurden bei der Elektroreduktion und bei der Phasentransfer-Katalyse die Ausbeuten an Carbinol (und Pinakol)3), die optische Ausbeute und die absolute Konfiguration des bevorzugt gebildeten Enantiomeren bestimmt. In der uberwiegenden Mehrzahl der untersuchten Beispiele besitzen die unter Mitwirkung optisch aktiver Ephedriniumsalze nach beiden Methoden erhaltenen Uberschusenantiomeren die entgegenges…
Electrochemical Conversion of Dichloroacetic Acid to Chloroacetic Acid in Conventional Cell and in Two Microfluidic Reactors
2013
The electrochemical conversion of dichloroacetic acid to chloracetic acid is investigated in conventional cells and in microreactors. Two different microreactors are used: the first is a filter press cell equipped with PTFE micrometric spacers, easy to assemble and disassemble and available for a large variety of electrodes and solvents; the second is made using an adhesive spacer, micromilling and press and could easily be developed on an industrial scale. The electrochemical synthesis is performed successfully in the microreactors equipped with a graphite cathode under proper operative conditions. The performance of the process strongly depends on the nature of the cathode and, for micror…
Electrochemical impedance spectroscopy of polyelectrolyte multilayer modified gold electrodes: influence of supporting electrolyte and temperature.
2005
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 observe…
Electrochemical reduction of carbon dioxide to formic acid at a tin cathode in divided and undivided cells: effect of carbon dioxide pressure and oth…
2016
Abstract The reduction of carbon dioxide to formic acid at a tin cathode was studied in both divided and undivided cells. In the first stage of the study, the effect of some operating parameters, including the working potential and the nature of the supporting electrolyte and of the cathode, on both the cathodic reduction of CO2 and the anodic oxidation of formic acid was investigated in a divided cell. In a second stage, the reduction of carbon dioxide was performed in an undivided cell with the aim of studying the effect on the generation of formic acid of various operating parameters such as current density, cathode to anode area ratio, mixing rate and nature of the anode and of the supp…
Ion transport through polyelectrolyte multilayers under steady-state conditions
2004
Abstract The permeability of a self-assembled polyelectrolyte multilayer to small ions under the influence of an applied potential difference is studied as a function of the number of layers and the nature of the supporting electrolyte. The multilayer is described as a series of homogeneously charged membranes with alternating sign of their fixed charge. Ion transport is described on the basis of the diffusion equation and the assumption of (Donnan) electrochemical equilibrium at the boundaries between layers. The calculated steady-state current–voltage curves are found to be in good agreement with experimental linear sweep voltammograms (at low sweep rate). The permeability of polystyrenes…
Electrochemical and Spectroelectrochemical Properties of Free-Base Pyridyl- and N -Alkyl-4-Pyridylporphyrins in Nonaqueous Media
2015
International audience; Twelve structurally related pyridyl and meso-N-methylpyridylporphyrin derivatives are investigated electrochemically in different nonaqueous media. The UV/Vis spectrum of each newly investigated porphyrin was measured before and after electro-reduction and, based on this data, the site of electron transfer is proposed. An interaction occurs between the meso-pyridyl or meso-N-alkyl-4-pyridyl substituents and the porphyrin p-ring system, the magnitude of which depends upon the number of linked pyridyl or N-alkyl-4-pyridyl groups in the compound, the solvent, the supporting electrolyte, and/or other anions added to the solution.
Die aufschlußfreie Bestimmung von Schwermetallen (Zn, Cd, Pb, Cu) in Getränken (Wein) durch inverse Voltammetrie in einer Durchflußzelle
1987
Digestion-free determination of trace-metals (Zn, Cd, Pb, Cu) in beverages by inverse voltammetry in a flow-through cell equipped with a mercury film-electrode is described. Optimal enrichment potentials are obtained by inspection of the pseudopolarograms of the elements in the original diluted sample solution. After the deposition step in the untreated sample solution stripping is effected in a proper supporting electrolyte after medium exchange. Values obtained by this techniques with various samples compare well with those obtained by usual procedures including wet digestion of the samples.
Synthesis of cyanoacetic acid by carbon dioxide and electrogenerated acetonitrile anion in undivided cells equipped with sacrificial anodes
2008
The electrochemical synthesis of cyanoacetic acid was performed by cathodic reduction of tetraalkylammonium salts (R4NX) in acetonitrile in undivided cells equipped with sacrificial anodes with concomitant or subsequent addition of carbon dioxide. These syntheses avoid the use of dangerous reagents, yield cyanoacetic acid in moderate faradic yields and confirm that the cathodic reduction of tetraalkylammonium salts in the presence of acetonitrile leads to the formation of the anion CNCH2-.