Nickel oxide hydrated

To improve the darkening characteristics of the device, a reservoir film that also darkens can be incorporated into the system. One material examined is hydrated nickel oxide. This is able to store Li reversibly and becomes darker when it is depleted, enhancing the darkening effect of the tungsten bronze layer. 

In alkaline solution nickelous hydroxide can be oxidized to n hydrated nickelic oxide, NiOo xHoO. This reaction is used in tin Edison storage cell. The electrodes of this cell are plates coated will Ni0.2 xHoO and metallic iron, which are converted on discharge of tlu cell into nickelous hydroxide and ferrous hydroxide, respectively. Tht electrolyte in this cell is a solution of sodium hydroxide. 

Fio. 17. Differential heats for the successive adsorptions at 30° of oxygen and carbon monoxide on hydrated nickel oxide. 

Nickel-cadmium batteries use a hydrate nickel oxide as positive electrode, a metallic cadmium as negative electrode and an aqueous solution of potassium hydroxide as electrolyte [17]. The production of electrons at the negative plate during discharge occurs via the following semi-reaction ... 

The nicad galvanic cell has cadmium anodes, hydrated nickel oxide cathodes, and KOH as the electrolyte. The electrodes are arranged In jelly-roll fashion. 

The electrochemical oxidation of the nickel is of special interest since it is a typical passivation metal in which very thin passive oxide films of a few nm thickness on the surface can cover the substrate metals efficiently. The passive oxide layer on the nickel was studied by Sikora and Mac Donald [118] who claimed that the passive film consisted of the inner nickel oxide of a barrier layer and an outer Ni(OH)2 porous or hydrated layer, in which the inner layer behaves as a p-type oxide with a cation vacancy. Oblonsky and Devine measured the surface enhanced Raman spectra of the nickel passivized in a neutral borate solution and estimated the amorphous Ni(OH)2 in the passive potential region and the NiOOH in the higher transpassive region [119]. Further, the passive films formed in the acidic and neutral solutions were assumed as partially hydrated nickel oxide [120,121]. The anodic film formed in the alkaline solution was assumed to be Ni(OH)2 in the... 

J. S. E. M. Svensson and C. G. Granqvist [1986] Electrochromic Hydrated Nickel Oxide Coatings for Energy Efficient Windows Optical Properties and Coloration Mechanism, Appl. Phys. Lett. 49, 1566-1568. 

The nickel—cadmium cell (nicad cell) is a conunou storage battery. It is a voltaic cell consisting of an anode of cadmium and a cathode of hydrated nickel oxide (approximately NiOOH) on nickel the electrolyte is potassium hydroxide. Nicad batteries are used in calculators, portable power tools, shavers, and toothbrushes. The half-cell reactions during discharge are... 

These rechargeable cells have a cadmium anode and a hydrated nickel oxide cathode. 

SurcaA., Orel B., Pihlar B., Bukovec P. Optical, spectroelectrochemical and structural properties of sol-gel derived Ni-oxide electrochromic film. J. Electroanal. Chem. 1996 408 83-100 SurcaA., Orel B. Sol-gel derived hydrated nickel oxide electrochromic films Optical, spectroelectrochemical and stmctural properties. J. Sol-Gel Sci. Technol. 1997 8 743-749 SurcaA., Bencic S., Orel B., Pihlar B. Spectroelectrochemical studies of V/Ti-, V/Ti/Zr- and V/Ti/Ce-oxide counter-electrode films. Electrochim. Acta 1999 44 3075-3084 SurcaA., Orel B., Opara Krasovec U., Lavren ii tangar U. Electrochromic and structural studies of nanocrystalline Fe/V (l 2)-oxide and crystallinelFc2V40i3 films. J. Electrochem. Soc. 2000 147 2358... 

A problem with sodium hypochlorite is its ability to chlorinate some compounds to form volatile reaction products. Ammonia and alkylamines, for example, can be chlorinated to form chloramines. The problem can be avoided by removing alkaline nitrogen compounds from the gas stream with an acid wash prior to the sodium hypochlorite scrubber. An alternative approach described by Valentin (1990) is the use of a catalyst in the scrubber liquid to promote oxidation. Hydrated nickelic oxide, which is formed in solution from nickel sulfate and sodium hypochlorite at a pH of 9 to lO.S, is recommended. A nickel concentration of 50-75 ppm is said to be effective, making removal of up to 95% of the odorous compounds possible in a single stage. 

A further example of a rechargeable battery is the nickel-iron cell. In the discharged state the negative plate of this cell is iron with hydrated ferrous oxide, and the positive plate is nickel with hydrated nickel oxide. When charged, the ferrous oxide is reduced to iron, and the nickel oxide is oxidized to a hydrated peroxide. The cell reaction may thus be represented by... 

In contrast to the sulfide ores, the lateritic ores were formed over long periods of time as a result of weathering of exposed nickel-containing rocks. The lateritic weathering process resulted in nickel solutions that were redeposited elsewhere in the form of oxides or siUcates. One type of laterite is nickeliferous limonitic iron laterite (Ee, Ni)O(OH) which consists primarily of hydrated iron oxide in which the nickel is dispersed in soHd solution. 

Electrodes. A number of different types of nickel oxide electrodes have been used. The term nickel oxide is common usage for the active materials that are actually hydrated hydroxides at nickel oxidation state 2+, in the discharged condition, and nickel oxide hydroxide [12026-04-9] NiO OH, nickel oxidation state 3+, in the charged condition. Nickelous hydroxide [12034-48-7J, Ni(OH)2, can be precipitated from acidic solutions of bivalent nickel... 

Jfickeloxydul, n. nickelous oxide, nickel(II) oxide, NiO. -hydrat, n, nickelous hydroxide, nickel (II) hydroxide, -salz, n. nickelous salt, nickel(II) salt, -verbindung,/. nickelous compound, nickel(II) compound. Nickelpapier, n. nickel foil, nickelplattiert, a. nickel-plated. 

The processes taking place on the positive electrode actually are more comph-cated. Several modifications of nickel oxides exist which in particular differ in their degrees of hydration, so the equations above do not correctly describe the water balance in the reaction. The hydroxide of divalent nickel is formed as p-Ni(OH)2 and... 

Hydrated nickel sulfate on heating at 103°C loses all of its water molecules. At 848°C, the anhydrous sulfate decomposes to nickel oxide and sulfur trioxide ... 

Examples for electrochromic behavior upon electrochemical oxidation can be found among group VIII metal oxides. Thin films of transparent hydrated iridium oxide turn blue-black, whereas nickel oxide switches from pale green to brown-black, possibly due to the absorbance of Ni3+ centers [26]. The systems are much less thoroughly investigated and a detailed mechanistic explanation is not known. However, proton extraction and anion insertion have been suggested. 

By reducing hydrated nickel(II) nitrate with NaBHt, in the presence of the tetradentate tripodal ligand np3 (equation 80), the complex [Ni(np3)j (66) has been obtained.263 Complex (66) undergoes oxidative reaction with HC104 or HBF4 to afford the nickel(II) hydrido complex [NiH ps)]-1".264 It also reacts with CO to give the carbonyl derivative263 and with white... 

Nickel(II) complexes containing up to four molecules of trialkylphosphines have been prepared by the direct reaction of a nickel(II) salt with the appropriate phosphine in either aprotic or protic solvents. Anaerobic conditions have sometimes been employed in order to avoid oxidation of unstable phosphines whereas dimethoxypropane has occasionally been employed as a dehydrating agent when using hydrated nickel(II) salts. 

Addition of potassium cyanide to aqueous solutions of the salt causes a marked deepening of the color, probably due to the formation of the unstable hexacyanonickelate (XI) ion. Mineral acids decompose the complex salt to form nickel cyanide alkaline oxidants destroy the material with the production of black hydrated nickel (III) oxide. 

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