Electrochemical characteristics oxidation

The overall pattern of behaviour of titanium in aqueous environments is perhaps best understood by consideration of the electrochemical characteristics of the metal/oxide and oxide-electrolyte system. The thermodynamic stability of oxides is dependent upon the electrical potential between the metal and the solution and the pH (see Section 1.4). The Ti/HjO system has been considered by Pourbaix". The thermodynamic stability of an... 

Hie electrochemical characteristics of overoxidation vary widely among polymers, solvents, and nucleophiles.129 Its rate depends on the degree of oxidation of the polymer (and therefore on the potential applied), and the concentration127 and reactivity of the nucleophile. Polypyrroles usually become overoxidized at lower potentials than polythiophenes because of their lower formal potentials for p-doping. In acetonitrile, the reactivity of the halides follows their nucleophilicity in aprotic solvents,... 

In 2000, it was proposed that the regioselectivity of the [3 + 2] cycloaddition of fullerenes could be modified under microwave irradiation. Under conventional heating, N-methylazomethine yhde and fullerene-(C7o) gave three different isomeric cycloadducts because of the low symmetry of C70 vs. Ceo. Using microwave irradiation and o-dichlorobenzene as a solvent, only two isomers were obtained, the major cycloadduct 114 being kinetically favored (Scheme 39) [75]. The same authors had previously reported the 1,3-dipolar cyclo addition of pyrazole nitrile oxides, generated in situ, to Geo under either conventional heating or microwave irradiation. The electrochemical characteristics of the cycloadduct obtained with this method made this product a candidate for photophysical apphcations [76]. 

H. Razmi and A. Azadbakht, Electrochemical characteristics of dopamine oxidation at palladium hexacyanoferrate film, electroless plated on aluminum electrode. Electrochim. Acta 50, 2193 (2005). 

Another vanadium oxide that has received much attention is LiVaOs, which has a layer structure composed of octahedral and trigonal bipyramidal ribbons that can be swelled just like other layered compounds and can intercalate lithium. Here again, the method of preparation is important to its electrochemical characteristics. West et al. made a systematic study of the impact of synthesis technique on capacity and cycling and showed that amorphous material increased the capacity above 2 V from 3—4 lithium per mole of LiVsOs at low current drains, 6—200 fiAlcm. ... 

The Ni(EtXant)3 complex (155) undergoes a reversible oxidation at -K1.92 V (312). The substituent effects in the electrochemical characteristics of the Ni(R2Dtc)2 and Ni(R2Dtc)J complexes are related to the inductive and meso-meric effects of the R groups. 

In order to increase the reaction rate and capacity, some methods to modify the surface structure and composition were recently attempted [42-49], They are surface oxidation [42-45] and surface fluorination [46-48] of graphite and carbon, and metal coating to carbon surface [49], These show that surface modifications are useful techniques to improve the electrochemical characteristics of graphite and carbon. 

From the absorbance change at certain wavelengths as the function of the given potential, we could obtain the electrochemical characteristics such as the redox potential. From the absorbance change as the function of the applied potential in Figure 13.3f>, the oxidation-reduction potential of PEO-cyt.c dissolved in 1/KCl... 

Polyaniline exists in various forms which differ in the oxidation state and degree of protonation of the main chain. The average oxidation state of the polymer main chain can be varied chemically or electrochemically. The structures of several common oxidation states are shown in Fig. 64. The degree of protonation can be varied by treatment with acid or base. In addition to the structure obtained from head-to-tail coupling at the para-position, other structural units can be obtained. These units can be obtained by substitutions at other positions of the phenyl group as well as head-to-head and tail-to-tail coupling (Fig. 65). The polymerization conditions determine the structural characteristics, oxidation state, and... 

Flavins (8), 8-azaflavin (9) and their analogs are characteristic oxidants toward thiols under anaerobic and other specific conditions (equation 12). S-Arylidene-l,3-dimethylbarbituric acid derivatives (10) also work as the oxidant in dioxane at 12(X-1S0 C, and the method was applied to synthesis of unsymmetrical disulfides. Electrochemical oxidation and photolysis of thiols to disulfidqs are also known. 

The lithiated transition metal oxide LiVMoOe has been synthesized by solid state reaction. This is the first report of this compound to be studied as an anode material. The synthesized LiVMo06 powder has been studied by means of X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) spectroscopy. The electrochemical characteristics of the prepared electrodes assembled in coin cells were also investigated in terms of half-cell performance. It is observed that the cell exhibits three stages of discharge plateaus in the ranges 2.1-2.0 V, 0.6-0.5 V and 0.2-0.01 V, respectively. 

Despite the good electrochemical characteristics and simplicity of preparation, Li Co02 is very expensive and highly toxic. These drawbacks have stimulated wide research activity targeted toward the development of alternate cathode materials for lithium-ion batteries. In this regard, hthium nickel oxide (LiJSIi02) could be more attractive due to its lower cost and toxicity. 

Thus lithiated manganese oxides with a substantial amount of nickel and other elements could play a crucial role in stabilizing the layered crystal structure, thereby improving the electrochemical characteristics. 

The redox potentials are determined by the differences in energy between two cobalt(III) and cobalt(II) states as a function of the apical substituents. Therefore, the electrochemical characteristics of the substituents should also correlate with other physical properties of the individual oxidation states provided these physical properties are affected by the substituents via the same mechanism [352]. 

Bipyranylidenes may be oxidized in two single-electron steps via bipyryliumyl radicals (47) to bipyrylium ions (48).Conversely, bipyrylium ions prepared by alternative routes may be reduced to bipyryliumyl radi-cals. The radical 47 (R = /Bu) has been characterized by ESR and the electrochemical characteristics of 47 (R = Ph, tBu, and others) have been determined.Decarboxylation of 4-carboxy-2,6-diphenyl-pyrylium ion in the presence of Vaska s compound [(Ph3P)2lrClCO] led to 47 (R = Ph) as the principal product, but whether the reaction involved... 

A persistent cation-radical 92 results from the oxidation of tetraphenyl-tliiophene. An ESR spectrum and g-value were recorded for this and other 4-substituted phenyl derivatives, although no assignments were made. The electrochemical characteristics of 92 have been investigated by Libert and Caullet, " and one of these authors has investigated the electrochemi-luminescent properties of systems involving 92. 

The only radicals to have been reported in this category are mentioned in work previously cited the transient existence of 197 (X = S, Se) has been inferred from electrochemical measurementsthe cis and trans isomers of dithiadiselenafulvalene have been oxidized anodically to cation-radicals in acetonitrile and the electrochemical characteristics compared with those of tetrathia- and tetraselenafulvalene. ... 

Active-passive behavior is dependent on the material-corrodent combination and is a function of the anodic or cathodic polarization effects, which occur in that specific combination. In most situations where active-passive behavior occurs, there is a thin layer at the metal surface that is more resistant to the environment than the underlying metal. In stainless steels, this layer is composed of various chromium and/or nickel oxides, which exhibit substantially different electrochemical characteristics than the underlying alloy. If this resistant, or passive, layer is damaged while in an aggressive environment, active corrosion of the freshly exposed surface will occur. The damage to... 

TABLE 3. Electrochemical characteristics of the oxidation of para-substituted anilines in DMF + TBABF4 at 25 °C... 

Two alternative routes (with the same final product and electrochemical characteristics) were also considered65. They include an irreversible proton transfer from 68a+ to 68a resulting in the deprotonated radical that is coupled in a subsequent step with parent 68a or its radical cation 68a1 However, in further work107 it was shown that the oxidation peak potential Epa does not depend on the concentration of the added base. vym-collidine (which is a stronger base in water than 68a). This indicates that 68a is not able to deprotonate its radical cation 68a1 and the mechanism involves only a true nucleophilic attack of 68a onto its radical cation 68a+ , as shown in Scheme 8. 

Fang, C. and Zhon, Y. (2001). The electrochemical characteristics of Cgo-glutathione modified Au electrode and the electrocatalytic oxidation of NADH, Electroanalysis, 13, 949-54. 

Ermakova, L.E. et al., Electrochemical characteristics of sihcon and titanium oxides and titanium-oxygen nanostructures on silica supports. Colloid J., 61, 714,1999. 

Table 26 summarizes the electrochemical characteristics of the first one-electron oxidation in these two families. 

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