Oxidation-reduction electrochemical

The toxicity (before and after treatment) of solutions subjected to a chemical or electrochemical oxidation/reduction treatment should always be tested. 

Electrochemical oxidation-reduction of eluting mixture components is the basis for amperometric electrochemical detectors. The three electrodes needed for the detection, the working (indicator) electrode, reference electrode, and auxiliary electrode, are either inserted into the flow stream or imbedded in the wall of the flow stream. See Figure 13.13. The indicator electrode is typically glassy carbon, platinum, or gold, the reference electrode a silver-silver chloride electrode, and the auxiliary a stainless steel electrode. Most often, the indicator electrode is polarized to cause oxidation of the mixture components... 

Electrochemical Activation. In the electrochemical method, catalytic nuclei of metal M on a noncatalytic surface S may be generated in an electrochemical oxidation-reduction reaction,... 

Figure 13. Schematic representation of the setup used for the infrared characterization of liquid-solid interfaces [63], The main cell consists of a platinum disk used for adsorption and reaction, a Cap2 prism for guidance of the infrared beam, and a liquid solution trapped between those two elements. The overall arrangement includes gas and liquid sample introduction stages as well as the electronics used for the electrochemical oxidation-reduction cycles needed to preclean the platinum surface.

Mercury, lead, cadmium and graphite are commonly used cathode materials showing large overpotentials for hydrogen evolution in aqueous solution. Liquid mercury exhibits a clean surface and is very convenient for small-scale laboratory use. Sheet lead has to be degreased and the surface can be activated in an electrochemical oxidation, reduction cycle [3, 22], Cadmium surfaces are conveniently prepared by plating from aqueous cadmium(ii) solutions on a steel cathode. 

Domenech A, Domenech-Carbo MT (2008) In situ AFM study of proton-assisted electrochemical oxidation/reduction of microparticles of organic dyes. Electrochem Com-mun 10 1238-1241. 

SOLION. A small electrochemical oxidation-reduction cell consisting of a small cylinder containing a solution and divided into sections by platinum gauze, porous ceramics, or other materials. A type of solion for detecting sound waves consists of a potassium iodide-iodine solution m which the iodide ions are oxidized to truodide ions at the anode, and the reverse process occurs at the cathode. The cell is constructed so that the sound waves cause agitation of the solution between die electrodes, and... 

Fig. 12.8. Test of reproducibility of electrochemical oxidation/reduction and of completeness of thermoinjections. Dependence of the oxidative charge on the reduction charge is shown in (a, b). The oxidation was performed in pure water immediately after reduction (all data in (b) and in (c)), after 72 h storage at room temperature ( ) and after 96h storage at -20°C ( ). Kinetics of the limiting oxidation current of wire gold electrode with reduced mercury before (1) and after (2) thermoinjection is shown in (c) [45].

G. Dryhurst and P.J. Elving, Electrochemical oxidation-reduction paths for pyrimidine, cytosine, purine and adenine. Correlation and application, Talanta, 16 (1969) 855-874. 

While such a device has yet to be constructed, Debreczeny and co-workers have synthesized and studied a linear D-A, -A2 triad suitable for implementation in such a device.11641 In this system, compound 6, a 4-aminonaphthalene monoimide (AN I) electron donor is excited selectively with 400 nm laser pulses. Electron transfer from the excited state of ANI to Ai, naphthalene-1,8 4,5-diimide (NI), occurs across a 2,5-dimethylphenyl bridge with x = 420 ps and a quantum yield of 0.95. The dynamics of charge separation and recombination in these systems have been well characterized.11651 Spontaneous charge shift to A2, pyromellitimide (PI), is thermodynamically uphill and does not occur. The mechanism for switching makes use of the large absorption cross-section of the NI- anion radical at 480 nm, (e = 28,300). A second laser pulse at 480 nm can selectively excite this chromophore and provide the necessary energy to move the electron from NI- to PI. These systems do not rely on electrochemical oxidation-reduction reactions at an electrode. Thus, switching occurs on a subpicosecond time scale. 

In summary, the electrochemical oxidation-reduction of organic molecules usually is mediated by the water (H20/H30+/H0 ) in the solvent matrix, especially if the substrate is more nucleophilic or electrophilic than water. Many reductions are catalyzed hydrogenations, and many oxidations are facilitated dehydrogenations. For these reasons, meaningful electrochemical measurements depend on the use of an inert electrode surface (not Pt, Pd, Au, or any other metal highly polished glassy carbon is the preferred choice in most cases). 

Activation polarization effect, which is associated with the kinetics of the electrochemical oxidation-reduction or charge-transfer reactions occurring at the electrode/electrolyte interfaces of the anode and the cathode. 

Electrochemical oxidation, reduction and formation of the C—X bond by direct and in direct processes have been reviewed3,248. 

Determination of T by means of TLE is accomplished as follows the electrolyte surface is cleaned by electrochemical oxidation/reduction in pure supporting electrolyte annealing can be carried out as described in refs. 32 and 41. If adsorption happens to be strong and the solution is very... 

Experimental Observations. The nearest we have come to demonstrating the existence of N—F ions is in the electrochemical oxidation-reduction reactions of HNF2. The oxidation has been carried out in water and in various polar organic solvents under acid conditions (15). The first step of this reaction is formation of the NF2 radical. The NF2 radical undergoes combination processes on the surface of the electrode rather than diffusing into the body of the solution before being involved in further reactions. The combination process on the electrode surface has been used to prepare various NF2 compounds by simultaneously generating other radical species—e.g.,... 

Electrodes. The first observations of SERS were made from species on silver electrodes. An essential prerequisite for a strong SERS signal from molecules adsorbed on the electrode, surface roughness, is obtained by running electrochemical oxidation-reduction cycles (ORC) (Chang and Laube, 1984 Koglin and Sequaris, 1986 Roth et al., 1993). During the oxidation half cycle a metal salt, usually a halide, is formed at the electrode surface ... 

As shown in Eq. (66), a stable stereoisomer (A) can be converted into another stable isomer (B) through electrochemical oxidation-reduction or reduction-oxidation, if a stereoisomeric unstable intermediate (A") is rapidly stereoisomerized to an isomeric intermediate (B"). Such an electrochemical stereoisomerization can sometimes be observed under cyclic voltammetric conditions for preparative isomerization reactions, AC electrolysis at a suitable frequency or undivided cell electrolysis may be useful. 

Because of their rich redox properties, NLO chromophores featuring transition metal complexes are among the best candidates for the role of NLO molecular switches, and the majority of examples reported up to now concerns metal-based chromophores in which the NLO response is modified by a chemical (or electrochemical) oxidation/reduction sequence. Several examples of reversible proton- or photon-driven switching of 0 will also be discussed in the following. 

Peak Potentials and Estimated Lifetimes of Ion Radicals in Electrochemical Oxidation—Reduction of Isoindoles ... 

A pretreatment that makes even basal plane carbon atoms accessible to oxidation is by electrochemical oxidation-reduction-cycles in 97% H2S04 oxidation of basal plane carbon atoms is also possible by ozone . ... 

The term "batteiy" refers to a device that converts the chemical energy contained in its active materials directly into the electric energy by means of an electrochemical oxidation-reduction (redox) reaction. There are two possible batteiy types primary and secondary. Primary batteries are non-rechargeable, whereas secondary batteries are rechargeable. Examples of primary batteries... 

Electrochromic polymers (ECPs) materials exhibit a change in transmittance and/ or reflectance of electromagnetic radiation induced by an electrochemical oxidation-reduction reaction (called electrochromism) (Rosseinsky and Mortimer, 2001). The ECPs can be used as electrochromic displays, glasses, and even fabrics (Remmele et al., 2015). A certain set of properties, such as, desired absorption profile, easily accessible redox process and ease of processing are of essential importance for materials to serve as effective electrochromes (Dyer and Reynolds, 2007). 

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