Search results for "Volta"
showing 10 items of 2055 documents
Evidence of intramolecular electron transfer between two metallic atoms in a bimetallic complex by electrochemical methods
2005
The electrochemical properties of the monomeric complex [(η5-C5H5)(μ-η5:η1-C5H4(CH2)2P(C6H5)2TiCl2] 1 and the heterobimetallic complex [(η5-C5H5)(μ-η5:η1-C5H4(CH2)2P(C6H5)2TiCl2][RuCl2(C6H4(CH3)(C3H7))] 2 have been studied by cyclic voltammetry, controlled potential electrolysis and rotating disk electrode voltammetry. An unexpected electron transfer between the two heterobimetallic atoms has been observed. This transfer takes place via an intramolecular interaction, hence via a chloride bridge. Electrochemical simulation has been carried out to verify experimental results and to obtain the kinetic constant of the proposed square scheme.
Hydrogel-supported protein-tethered bilayer lipid membranes: a new approach toward polymer-supported lipid membranes
2011
Polymer-supported bilayer lipid membranes offer great opportunities for the investigation of functional membrane proteins. Here we present a new approach in this direction by introducing a thin hydrogel layer as a soft ‘cushion’ on indium–tin oxide (ITO), providing a smooth, functional surface to form the protein-tethered BLM (ptBLM). ITO was used as a transparent electrode, enabling simultaneous implementation of electrochemical and optical waveguide techniques. The hydrogel poly(N-(2-hydroxyethyl)acrylamide-co-5-acrylamido-1-carboxypentyl-iminodiacetate-co-4-benzoylphenyl methacrylate) (P(HEAAm-co-NTAAAm-co-MABP)) was functionalized with the nickel chelating nitrilotriacetic acid (NTA) gr…
Substituent effect on the redox potential of substituted (aryl)(2-nitrobenzo[ b ]thiophen-3-yl)amines
2001
Abstract The electronic effect of some meta- or para-substituents on the reduction of the title compounds has been investigated. The reversible reduction potential values of these compounds have been evaluated by cyclic voltammetry at a mercury electrode in 0.1 M tetraethylammoniumtetrafluoroborate, dimethylsulfoxide solutions. The substituent effect depends on both its nature and its position. The reduction potential values of the derivatives studied have been correlated with the Hammett substituent constants.
Performance of interdigitated nanoelectrodes for electrochemical DNA biosensor.
2003
An electrochemical methodology for bio-molecule sensing using an array of well-defined nanostructures is presented. We describe the fabrication by e-beam lithography of nanoelectrodes consisting of a 100 micro m x 50 micro m area containing interdigitated electrodes of 100 nm in width and interelectrode distance of 200 nm. Sensitivity and response time of the nanoelectrodes are compared to the responses of macro- and microelectrodes. The specificity of the sensor is studied by modifying the gold electrodes with DNA. The technique enables to characterize both single and double-stranded DNA of 15 nucleotides. A special electrochemical cell is adapted to control the temperature and measure the…
Thermal behaviour and electrochemical properties of bis(trifluoromethanesulfonyl)amide and dodecatungstosilicate viologen dimers
2012
We report the synthesis and characterization of dimeric viologen salts (1',1''-(alkane-1,n-diyl)bis(1-ethyl-4,4'-bipyridinium) with n = 4-10) with bis(trifluoromethanesulfonyl)amide (bistriflimide, Tf(2)N(-)) as a counteranion. For n = 4, 5 and 6, and for the nonylviologen cation (1,1'-dinonyl-4,4'-bipyridinium) we also prepared salts with the totally inorganic dodecatungstosilicate anion, SiW(12)O(40)(4-), featuring a poly-charged surface and nanosized dimensions. The materials have been characterized by means of calorimetric techniques, X-ray diffraction and solid state NMR and a comparison is made with analogous monomeric viologen salts exhibiting smectic mesophases. A strong odd-even ef…
Operational Mechanism of Conjugated Polyelectrolytes
2014
Conjugated polyelectrolytes (CPEs) are versatile materials used in a range of organic optoelectronic applications. Because of their ionic/electronic nature, characterizing these materials is nontrivial, and their operational mechanism is not fully understood. In this work we use a methodology that combines constant-voltage-driven current-density transient measurements with fast current vs voltage scans to allow decoupling of ionic and electronic phenomena. This technique is applied to diodes prepared with cationic CPEs having different charge-compensating anions. Our results indicate that the operational mechanism of these devices is governed by electrochemical doping of the CPE. On the bas…
Dating archeological lead artifacts from measurement of the corrosion content using the voltammetry of microparticles.
2011
A methodology for dating archeological lead artifacts based on the voltammetry of microparticles is described. This methodology is based on the comparison of the height of speci¿c voltammetric features from PbO2 and PbO corrosion products formed under long-term alteration conditions. Calibration of the method was performed with the help of a series of well-documented lead pieces from the funds of di¿erent museums of the Comunitat Valenciana (Spain) covering from the ¿fth century B.C. to present day. The variation of peak currents with the time of corrosion can be¿tted to the same potential rate law as that found by Reich (R = 0.070 ( 0.005), using measurements on the Meissner fraction in th…
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.
Electrostatic field theory and circuit analysis in the design of coalescers with pulsed dc voltage
2009
This paper presents a mathematical analysis of the electric field and interfacial free charge experienced by the emulsion in an electrostatic coalescer that is subjected to a pulsed dc voltage. Previous work in this area is re-assessed, but the analysis is expanded. A novel static analysis of the system is presented, giving valuable physical insight. It becomes obvious that there must be a limited range of frequencies that are effective in a pulsed dc scheme. Thereafter, analytical expressions for the steady-state solution, where both the switching frequency and duty ratio (or mark space ratio) can be varied, are presented for the first time. These expressions are used to derive voltage and…