Electrosynthesis

Different classifications of electrochemical reactors can be made depending on their configuration (divided, undivided cathodic, and anodic compartments) electrode geometry (bi- and tri-dimensional), the fluid flow through the reactor (mixing, plug-flow, fluidized baths), among others. There are several demands for electrochemical reactors (Pletcher and Walsh, 1990 Molina et al., 2004)  

The methodology used in chemical engineering to describe the performance of chemical reactors can be adapted to the study of electrochemical cells. Electrosynthesis of a variety of industrially relevant products has been studied for instance, the synthesis of ammonia from natural gas at atmospheric pressure (Marnellos et al., 2001 Wang et al., 2007). 

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A microelectrode is an electrode with at least one dimension small enough that its properties are a fimction of size, typically with at least one dimension smaller than 50 pm [28, 29, 30, 31, 32 and 33]. If compared with electrodes employed in industrial-scale electrosynthesis or in laboratory-scale synthesis, where the characteristic dimensions can be of the order of metres and centimetres, respectively, or electrodes for voltannnetry with millimetre dimension, it is clear that the size of the electrodes can vary dramatically. This enonnous difference in size gives microelectrodes their unique properties of increased rate of mass transport, faster response and decreased reliance on the presence of a conducting medium. Over the past 15 years, microelectrodes have made a tremendous impact in electrochemistry. They have, for example, been used to improve the sensitivity of ASV in enviroiunental analysis, to investigate rapid... 

The industrial economy depends heavily on electrochemical processes. Electrochemical systems have inherent advantages such as ambient temperature operation, easily controlled reaction rates, and minimal environmental impact (qv). Electrosynthesis is used in a number of commercial processes. Batteries and fuel cells, used for the interconversion and storage of energy, are not limited by the Carnot efficiency of thermal devices. Corrosion, another electrochemical process, is estimated to cost hundreds of millions of dollars aimuaUy in the United States alone (see Corrosion and CORROSION control). Electrochemical systems can be described using the fundamental principles of thermodynamics, kinetics, and transport phenomena. 

Electrochemical systems are found in a number of industrial processes. In addition to the subsequent discussions of electrosynthesis, electrochemical techniques are used to measure transport and kinetic properties of systems (see Electroanalyticaltechniques) to provide energy (see Batteries Euel cells) and to produce materials (see Electroplating). Electrochemistry can also play a destmctive role (see Corrosion and corrosion control). The fundamentals necessary to analyze most electrochemical systems have been presented. More details of the fundamentals of electrochemistry are contained in the general references. 

D. Degner ia E. Steckhan, ed.. Organic Electrosynthesis in Industry, Electrochemistry III, Topics in Current Chemisty, Vol. 148, Spriager-Vedag, Berlin, 1988,... 

Mixed Kolbe electrosynthesis ot two perfluoroacids leads to a mixture of three products, as is generally expected [7S] (equation 69)... 

Interest in using ionic liquid (IL) media as alternatives to traditional organic solvents in synthesis [1 ], in liquid/liquid separations from aqueous solutions [5-9], and as liquid electrolytes for electrochemical processes, including electrosynthesis, primarily focus on the unique combination of properties exhibited by ILs that differentiate them from molecular solvents. 

Lead(II) phthalocyanine can be prepared by heating lead(II) oxide with the respective phthalonitrile without solvent150-159 or in 1-chloronaphthatene.154 Addition of anhydrous lead(II) acetate to a solution of dilithium phthalocyanine in anhydrous alcohol gives a precipitate of lead phthalocyanine.59 Lead phthalocyanine can also be obtained by electrosynthesis.160... 

Inorganic electrosynthesis in non-aqueous solvents. B. L. Laube and C. D. Schmulbach, Prog. 

There are various ways in which CMEs can benefit analytical applications. These include acceleration of electron-transfer reactions, preferential accumulation, or selective membrane permeation. Such steps can impart higher selectivity, sensitivity, or stability to electrochemical devices. These analytical applications and improvements have been extensively reviewed (35-37). Many other important applications, including electrochromic display devices, controlled release of drugs, electrosynthesis, and corrosion protection, should also benefit from the rational design of electrode surfaces. 

Polypyrrole relatives obtained by electrosynthesis in the presence of different small inorganic or organic counter-ions that are interchanged with the electrolyte during electrochemical control of the material. 

One of the major potential applications of conducting polymers is as mediators or catalysts for electrochemical sensors and electrosynthesis. 

It was also observed that, with the exception of polyacetylene, all important conducting polymers can be electrochemically produced by anodic oxidation moreover, in contrast to chemical methoconducting films are formed directly on the electrode. This stimulated research teams in the field of electrochemistry to study the electrosynthesis of these materials. Most recently, new fields of application, ranging from anti-corrosives through modified electrodes to microelectronic devices, have aroused electrochemists interest in this class of compounds... 

Electrolysis of carboxylate ions, which results in decarboxylation and combination of the resulting radicals, is called the Kolbe reaction or the Kolbe electrosynthesis. 

Schwarz DE, Frenkel AI, Nuzzo RG, Rauchfuss TB, Vairavamurthy A (2004) Electrosynthesis of Re 4. XAS analysis of ReS2, Re2S7, and ReS4. Chem Mater 16 151-158... 

Utilizing low-oxidation selenium precursors appears to be particularly suited for obtaining single-phase ZnSe deposits. Results have been presented of ZnSe electrosynthesis from alkaline selenosulfate solutions of complexed Zn(II) [108]. 

Aqueous electrolytes proposed in the literature for cathodic electrodeposition of lead selenide are generally composed of dissolved selenous anhydride and a lead salt, such as nitrate or acetate. Polycrystalline PbSe films have been prepared by conventional electrosynthesis from ordinary acidic solutions of this kind on polycrystalline Pt, Au, Ti, and Sn02/glass electrodes. The main problem with these applications was the PbSe dendritic growth. Better controlled deposition has been achieved by using EDTA in order to prevent PbSeOs precipitation, and also acetic acid to prevent lead salt hydrolysis. 

Bouroushian M, Kosanovic T, Spyrellis N (2006) A pulse plating method for the electrosynthesis of ZnSe. J Appl Electrochem 36 821-826... 

Ham D, Mishra KK, Rajeshwar K (1991) Anodic electrosynthesis of cadmium selenide thin films. Characterization and comparison with the passive/transpassive behavior of the CdX (X = S, Te) counterparts. J Electrochem Soc 138 100-108 Stimming U (1985) Photoelectrochemical studies of passive films (Review Article). Electrochim Acta 31 ... 

Ham D, Mishra KK, Weiss A, Rajeshwar K (1989) Anodic electrosynthesis of CdTe thin films. Chem Mater 1 619-625... 

Sanchez S, Lucas C, Picard GS, Bermejo MR, CastriUejo Y (2000) Molten salt route for ZnSe high-temperature electrosynthesis. Thin Solid Films 361-362 107-112... 

Schimmel Ml, Tacconi NR, Rajeshwar K (1998) Anodic electrosynthesis of CU2S and CulnS2 films. J Electroanal Chem 453 187-195... 

Pawar SM, Moholkar AV, Suryavanshi UB, Rajpure KY, Bhosale CH (2007) Electrosynthesis and characterization of iron selenide thin films. Sol Energy Mater Sol Cells 91 560-565... 

Mohite UK, Lokhande CD (1996) Electrosynthesis of yttrium chalcogenides from a non-aqueous bath. Appl Surf Sci 92 151-154... 

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