Search results for "Electrolyte"
showing 10 items of 746 documents
Electrolyte-driven electrochemical amplification by poly(thienylacetylene) encapsulated within Zeolite Y
2006
Electrochemical oxidation and reduction of poly(thienylacetylene) encapsulated inside zeolite Y (PTA@Y) exhibit with large anodic and cathodic doping currents with a significant reversibility. Thienyl groups lower the redox potential of polyacetylene chain whereas encapsulation stabilizes the resulting charged radical species blocking undesired post electron-transfer cross-link reactions. Size-exclusion effects associated produces an electrolyte-dependent amplification of currents recorded at PTA@Y-modified electrodes for electrochemical processes involving selected substrates in solution, namely, dinitrobiphenyl and benzidine. Keywords: Poly(thienylacetylene), Zeolite Y, Electrochemistry, …
Electrodeposition methods in superheavy element chemistry
2008
To prepare electrodeposition experiments with superheavy elements (SHE), their homologs were investigated. In the experiments, various electrode materials and electrolytes were used. Critical potentials (E crit ) where the electrodeposition starts and potentials for the deposition of 50% of the atoms in solution (E 50% ) were determined. Underpotential deposition was observed in most cases. An electrolytic cell for a fast electrochemical deposition was developed and the time for the deposition of 50% of the atoms in solution (t 50% ) was determined. Short lived α-emitting isotopes were produced at Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, transferred to the aqueous phase with …
Contact Potentials, Fermi Level Equilibration, and Surface Charging.
2016
This article focuses on contact electrification from thermodynamic equilibration of the electrochemical potential of the electrons of two conductors upon contact. The contact potential difference generated in bimetallic macro- and nanosystems, the Fermi level after the contact, and the amount and location of the charge transferred from one metal to the other are discussed. The three geometries considered are spheres in contact, Janus particles, and core-shell particles. In addition, the force between the two spheres in contact with each other is calculated and is found to be attractive. A simple electrostatic model for calculating charge distribution and potential profiles in both vacuum an…
Stabilizing Lead Cathodes with Diammonium Salt Additives in the Deoxygenation of Aromatic Amides
2014
Lead is efficiently protected against cathodic corrosion by the addition of diammonium salts in the electrolyte. The cationic coating of the cathode allows the efficient electroreduction of benzamides to benzylamines. The electrochemical deoxygenation of the amide is achieved without the use of oxophilic agents or sacrificial anodes. The surface of the lead cathode stays smooth and the cathode can be reused for multiple runs, providing <2.5 ppm of the crude product. Cyclic voltammetry studies reveal a shift in the onset potential of the hydrogen evolution reaction by −157 mV.
Local electrochemical impedance measurements on inclusion-containing stainless steels using microcapillary-based techniques
2009
MnS inclusions are good precursor sites for pitting corrosion of stainless steel. The objective of this paper was to quantify the passive properties of resulfurized stainless steel after immersion in chloride media. This was done by combining microcapillary techniques with electrochemical impedance spectroscopy and numerical analysis (specific equivalent circuit). It was shown that sulfur species produced in the electrolyte during the dissolution of inclusions react with the native passive film to CrS and FeSO 4 . Local electrochemical impedance spectroscopy measurements provided data describing the behaviour of the affected matrix at the microscale. For example, the value of the charge tra…
Convective electrodiffusion processes through graft-modified charged porous membranes
1999
Convective diffusion and electrophoresis across a charged porous membrane showing variable permeability properties were studied. The membrane used was prepared by grafting poly(acrylic acid) (PAA) onto a porous polyvinylidene fluoride (PVDF) membrane. The degree of grafting was selected to be relatively low, 18 wt%, to compromise between the ion selectivity and hydraulic permeability of the membrane. The possible electric field induced effects on the membrane permselectivity were examined after the membrane had been characterized by convective diffusion and concentration cell potential measurements. The measured electrophoresis data, however, could be modelled using the extended Teorell–Mey…
Effect of cationic polyamidoamine dendrimers on ionic transport through nanochannels
2021
Abstract The effect of polyamidoamine (PAMAM) dendrimers (generations G0–G3) on the ion transport properties of nanochannels (conical and cylindrical) is studied either by surface functionalization or by addition to the electrolyte solution. Surface functionalization with cationic dendrimers lead to inversion of the ion current rectification, indicating the anion selectivity of the modified nanochannels. This anion selectivity increases by immobilizing higher-generation dendrimers, as expected for an increase in the surface density of amino groups. However, compared to PAMAM G2, functionalization with PAMAM G3 results in higher cation and lower anion fluxes. Diffusion experiments of charged…
Li-ion diffusion in Li_{x}Nb_{9}PO_{25}$
2013
Abstract Wadsley–Roth phase Li x Nb 9 PO 25 has been studied as a potential candidate for anode material of Li-ion batteries. Its crystal structure, which consists of ReO 3 -type blocks of NbO 6 octahedra connected with PO 4 tetrahedra, provides a good stability and performance during Li + insertion/removal. Li-ion chemical diffusion coefficient ( D chem ) in Li x Nb 9 PO 25 was determined by means of potentiostatic intermittent titration technique and electrochemical impedance spectroscopy. Different data treatments (classical Warburg equation or the model of an electrode system with ohmic potential drop and/or slow kinetics of the interfacial Li + ion transfer across the electrode/electro…
The anodic and cathodic dissolution of Al and Al–Cu–Mg alloy
2010
Abstract Atomic emission spectroelectrochemistry (AESEC) was used to monitor the release of Al from 99.99% aluminum (1199 alloy) and Al, Mg, and Cu from 2024 Al alloy in 30 g/l NaCl electrolyte as a function of pH. The cathodic dissolution of Al was demonstrated and attributed to an increase in the pH at the interface due to the water reduction reaction. The dissolution of Mg was also observed but was a more complex function of current probably depending on the interfacial pH and the Al dissolution rate. The detachment of copper-rich particles was observed as very rapid spectroscopic emission transients (peak width
Electrochemical synthesis on boron-doped diamond
2012
Abstract Boron-doped diamond (BDD) is a novel and innovative electrode material. In protic media and particular aqueous electrolytes BDD exhibits a large over potential for the evolution of molecular hydrogen and oxygen. The large chemical window allows a variety of electrochemical conversions to be conducted. The anodic process treatment generates oxyl species directly which are known to be extremely reactive. Usually, the electrochemical mineralization of the organic components in the electrolyte occurs. However, with control of the reactivity of these intermediates the use in electroorganic synthesis can be realized. Until today mostly anodic conversions have been studied at BDD. Since h…