Reductive decomposition

Dispersed Metals. Bifimctional zeoHte catalysts, principally zeoHte Y, are used in commercial processes such as hydrocracking. These are acidic zeoHtes containing dispersed metals such as platinum or palladium. The metals are introduced by cation exchange of the ammine complexes, foUowed by a reductive decomposition (21) ... 

BM Structure, composition, and properties should be similar and (4) the FM-containing elements should be able to bring about chemical reduction/decomposition or physical removal of BM oxide film. 

Kinetic stability of lithium and the lithiated carbons results from film formation which yields protective layers on lithium or on the surfaces of carbonaceous materials, able to conduct lithium ions and to prevent the electrolyte from continuously being reduced film formation at the Li/PC interphase by the reductive decomposition of PC or EC/DMC yielding alkyl-carbonates passivates lithium, in contrast to the situation with DEC where lithium is dissolved to form lithium ethylcarbonate [149]. EMC is superior to DMC as a single solvent, due to better surface film properties at the carbon electrode [151]. However, the quality of films can be increased further by using the mixed solvent EMC/EC, in contrast to the recently proposed solvent methyl propyl carbonate (MPC) which may be used as a single sol-... 

The following reactions proposed by Aurbach and co-workers are examples of the reductive decomposition reactions of anions with lithium [199, 169] ... 

Core Sizes of Au. SR Clusters Formed by Reductive Decomposition of Au(I) SR Polymer... 

Transition metal- or haem protein-mediated oxidative or reductive decomposition. 

The reductive decomposition of alkylmercury compounds is also a useful source of radicals.300 The organomercury compounds are available by oxymercuration (see Section 4.1.3) or from organometallic compounds as a result of metal-metal exchange (see Section 7.3.3). 

Endo E., Tanaka K. and Seika K. Initial Reaction in the Reduction Decomposition of Electrolyte Solutions for Lithium Batteries, J. Electrochem. Soc., 147, 4029-4033 (2000). 

The charge carriers may reduce or oxidize the semiconductor itself leading to decomposition. This poses a serious problem for practical photoelectrochemical devices. Absolute thermodynamic stability can be achieved if the redox potential of oxidative decomposition reaction lies below the valence band and the redox potential of the reductive decomposition reaction lies above the conduction band. In most cases, usually one or both redox potentials lie within the bandgap. Then the stability depends on the competition between thermodynamically possible reactions. When the redox potentials of electrode decomposition reactions are thermodynamically more favored than electrolyte redox reactions, the result is electrode instability, for example, ZnO, Cu20, and CdS in an aqueous electrolyte. 

The reactions that are more favored thermodynamically tend to be also favored kineti-cally. Semiconductor electrodes can be stabilized by using this effect. For this purpose, redox couples in the electrolyte are established with the redox potential more negative than the oxidative decomposition potential, or more positive than reductive decomposition potential in such a manner that the electrolyte redox reaction occurs preferentially compared to the electrode decomposition reaction. 

Chemical bleaching is used to remove colored non-washable soils and stains adhering to fibers and is accomplished by oxidative or reductive decomposition of chromophoric systems. Only oxidative bleaches are used in laundry products to a great extent. 

This reductive decomposition process occurs oniy during the first charge and is absent in the foiiowing cycies so that the carbonaceous anode can be cycied many times in the eiectroiyte, yieiding stable capacity. 

In voltammetric experiments, the oxidative or reductive decompositions of the investigated electrolyte components (solvents or salts) are made to occur on an electrode whose potential is controlled, and the corresponding decomposition current recorded as the function of the potential is used as the criterion for... 

Endo et al. investigated the reductive decomposition of various electrolytes on graphite anode materials by electron spin resonance (ESR). In all of the electrolyte compositions investigated, which included LiC104, LiBF4, and LiPFe as salts and PC, DMC, and other esters or ethers as solvents, the solvent-related radical species, which were considered to be the intermediates of reductive decomposition, were detected only after prolonged cathodic electrolysis. With the aid of molecular orbital calculation, they found that the reduction of salt anion species is very difficult, as indicated by their positive reduction enthalpy and that of free solvent (A/4 — 1 kcal mol ). However, the coordination of lithium ions with these solvents dramatically reduces the corresponding reduction enthalpy (A/ —10 kcal mol ) and renders the reaction thermodynamically favored. In other words, if no kinetic factors were to be considered, the SEI formed on carbonaceous anodes... 

On the basis of the results from XPS studies by Kanamura and co-workers that the SEI has a multilayered structure,Peled and co-workers modified their lithium electrode passivation model to include carbonaceous anodes and proposed a so-called mosaic model to describe the SEI structure on the anode, as Figure 15a shows.According to this model, multiple reductive decompositions occur between the negatively charged anode surface and the various electrolyte components simultaneously, depositing a mixture of insoluble products on the anode. This heteropolymicrophase SEI consists of many microregions that are of entirely different chemical... 

Overcharge tests were carried out in LiCo02 cathode half-cells that contained these additives, and a redox shuttle effect was observed between 4.20 and 4.30 V, close to the redox potentials of these additives. The same shuttling effect was observed even after 2 months of storage for these cells, indicating the stability and redox reversibility of these additives. A closer examination of the capacity retention revealed that 4-bromo-l,2-dimethoxybenzene seemed to have the best shuttle-voltage performance for the 4.0 V lithium cell used." The stability of these additives against reductive decomposition was also tested by the authors on metallic lithium as well as on carbonaceous anodes, and no deterioration was detected. 

Coulombic efficiency in the first charging cycle comparable to that of the commercial electrolytes for lithium ion cells.The potential plateau at 0.80 V, characteristic of the reductive decomposition of PC, was completely eliminated due to the presence of ClEC, while a new process was observed at 1.70 V. When taking the irreversible capacity in the first cycle as a metric, the optimum concentration of ClEC was determined to be 30 vol although in a... 

Scheme 29. Proposed Mechanism for BOB Reductive Decomposition on a Graphitic Surface at Low Potentials...

While confirming the results reported by Wang et al. that TMP is cathodically instable, the authors also showed that longer alkyl substituents (as in TEP) improved cathodic stability, although, in long-term cycling or storage at elevated temperatures, the reductive decomposition of TEP still caused poor cell... 

An unexpected result was obtained when DTBB-catalyzed lithiation was applied to the vinyl-oxetane 313 . After work-up, lactone 314 was isolated, the process being explained by an elimination reaction via a radical pathway more than by reduction of the benzyl radical into the anion. Thus, this hypothetical intennediate reacted with the lithium enolate of acetaldehyde, generated in situ by reductive decomposition of THF (Scheme 92). 

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