Powder electrodes, compound

The preparation of nickel oxide deposits with high surface area on steel, nickel, copper, graphite or titanium electrodes partly for anodic oxidation of organic compounds and the preparation of pressed nickel oxide powder electrodes mainly for application in storage batteries is described. The performance of nickel oxide anodes for batteries is improved by addition of cobaltflljhydroxide... 

The low enantioselectivity in these cases can be explained by low coverage of chiral species on electrode surfaces. Therefore, some attempts were undertaken to use metal hydrogenating catalysts as electrode materials. But at first only ee values of 2-6% were obtained in the reduction of 2-oxo compounds into alcohols using Raney-Ni powder electrodes modified with... 

Two types of powder electrodes can be distinguished and they have quite different characteristics. Electrodes belonging to one type are called powder electrodes of the first kind and electrodes belonging to the other types are called compound powder electrodes. 

Powder electrodes of the first kind fulfill the following conditions the powder in the electrode is a pure metal by which the platinum leading-out electrode is covered the solution contains ions of that metal. Thus under such conditions both the leading-out electrode and the powder correspond to reversible electrodes of the first kind differing only in the dispersion of the metallic component. Powder electrodes not having this structure are compound powder electrodes. 

For a well constructed compound powder electrode, the potential value is a parameter particularly important for investigations on contacts and absorbents because exist the connection between the potential and the state of the surface, the catalytic and adsorption properties of powders, and also the surface concentration of the substance adsorbed. 

IV. THE MECHANISM OF ESTABLISHING THE POTENTIAL OF A COMPOUND POWDER ELECTRODE... 

Recently we tested the application of powder electrodes to investigations on organic compounds. We are of the opinion that if an organic substance poorly soluble in water is to be selected... 

Both substances differ in color, 1 red, 2, yellow and in crystallographic nature. Each is stable in the other range of concentration of hydrogen ions. The aqueous solution of potassium chloride was saturated by both compounds, and by adding either hydrochloric acid (HCl) or an aqueous solution of potassium hydroxide (KOH) we obtained corresponding pH values of the solution. We dipped powder electrodes in solutions prepared in this way—one series with compound 1, the second series with compound 2 (in separate containers). The powder electrodes were specially constructed to facilitate measurement. 

When nickel hydroxide is oxidized at the nickel electrode in alkaline storage batteries the black trivalent gelatinous nickel hydroxide oxide [12026-04-9], Ni(0H)0, is formed. In nickel battery technology, nickel hydroxide oxide is known as the nickel active mass (see Batteries, secondary cells). Nickel hydroxide nitrate [56171-41-6], Ni(0H)N02, and nickel chloride hydroxide [25965-88-2], NiCl(OH), are frequently mentioned as intermediates for the production of nickel powder in aqueous solution. The binding energies for these compounds have been studied (55). 

In the lithium-ion approach, the metallic lithium anode is replaced by a lithium intercalation material. Then, tw O intercalation compound hosts, with high reversibility, are used as electrodes. The structures of the two electrode hosts are not significantly altered as the cell is cycled. Therefore the surface area of both elecftodes can be kept small and constant. In a practical cell, the surface area of the powders used to make up the elecftodes is nomrally in the 1 m /g range and does not increase with cycle number [4]. This means the safety problems of AA and larger size cells can be solved. 

Electrocatalytic hydrogenation has the advantage of milder reaction conditions compared to catalytic hydrogenation. The development of various electrode materials (e.g., massive electrodes, powder cathodes, polymer film electrodes) and the optimization of reaction conditions have led to highly selective electrocatalytic hydrogenations. These are very suitable for the conversion of aliphatic and aromatic nitro compounds to amines and a, fi-unsaturated ketones to saturated ketones. The field is reviewed with 173 references in [158]. While the reduction of conjugated enones does not always proceed chemoselectively at a Hg cathode, the use of a carbon felt electrode coated with polyviologen/Pd particles provided saturated ketones exclusively (Fig. 34) [159]. 

Elemental composition Cu 64.18%, Cl 35.82%. Copper(I) chloride is dissolved in nitric acid, diluted appropriately and analyzed for copper by AA or ICP techniques or determined nondestructively by X-ray techniques (see Copper). For chloride analysis, a small amount of powdered material is dissolved in water and the aqueous solution titrated against a standard solution of silver nitrate using potassium chromate indicator. Alternatively, chloride ion in aqueous solution may be analyzed by ion chromatography or chloride ion-selective electrode. Although the compound is only sparingly soluble in water, detection limits in these analyses are in low ppm levels, and, therefore, dissolving 100 mg in a liter of water should be adequate to carry out aU analyses. 

In this paper, the selectivity of the ECH method for the reduction of nitro compounds to the corresponding amines on RCu electrodes will be compared with that of reduction by RCu alloy powder in alkaline aqueous ethanol. In the latter method (termed chemical catalytic hydrogenation (CCH)), chemisorbed hydrogen is generated in situ but by reduction of water by aluminium (by leaching of the alloy) (equation [12]). The reductions by in situ leaching must be carried out in a basic medium in order to ensure the conversion of insoluble Al(OH)3 into soluble aluminate (equation [12]). The selectivity and efficiency of the electrochemical reduction of 5-nitro-indoles, -benzofurane, and -benzothiophene at RCu electrodes in neutral and alkaline aqueous ethanol will also be compared with that of the classical reduction with zinc in acidic medium. 

Cobalt pkthalocyanine as catalyst in alkaline electrolyte. Jasinski 1 2> was the first to show that CoPc in alkaline solution showed a pronounced activity for the cathodic reduction of oxygen. The compound was mixed with powdered nickel in a ratio of 1 10 w/w and pressed into a stainless steel tube (geometrical surface of the electrode 0.5 cm2). The tube served for both current conduction and gas supply. 

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