Cations insertion

The value of the EQCM is exemplified by the data shown in Fig. 17.177 The first reduction of the polypyrrole film was initially accompanied by a mass decrease, as expected for anion expulsion according to Eq. (1). However, after the reduction was ca. 75% complete, the mass began to increase, indicating a switch of the charge neutralization mechanism to cation insertion [Eq. (5)]. 

One of the key steps en route to a 3-D nanoscopic battery requires fabricating an ultrathin film of a polymer separator/electrolyte over chemically stable, physically rugged, cation-insertion oxide scaffolds, such as supported films of MnOx ambigels. ° In... 

The authors proposed the following picture of the silylene anion-radical formation. Treatment of the starting material by the naphthalene anion-radical salt with lithium or sodium (the metals are denoted here as M) results in two-electron reduction of >Si=Si< bond with the formation of >SiM—MSi< intermediate. The existence of this intermediate was experimentally proven. The crown ether removes the alkali cation, leaving behind the >Si - Si< counterpart. This sharply increases electrostatic repulsion within the silicon-silicon bond and generates the driving force for its dissociation. In a control experiment, with the alkali cation inserted into the crown ether, >Si — Si< species does dissociate into two [>Si ] particles. 

Alternative approaches exist to explaine the mechanism of chemical interaction. It is accepted that water is formed as a result of mechanochemical interaction, solid reagents are dissolved in water, and the reaction proceeds via the dissolved state (hydrothermal-like process). On the other hand, it is assumed that the initial stages of the process involve the interaction between acid and base centers present at the surfaces in contact, and the next stages are connected with the process of calcium cations insertion into aluminum hydroxide lattice. 

In contact with aqueous alkaline media, metal oxide electrochemistry is dominated by hydroxylation processes. However, in contact with acidic media, proton and cation insertion processes occur, eventually leading to complicated responses where reductive or oxidative dissolution processes frequently take place (Scholz and Meyer, 1998 Grygar et al., 2002 Scholz et al., 2005). As far as such processes involve disintegration of the porous structure of the material, electrochemically assisted dissolution processes will be taken only tangentially here. 

Redox conductivity of conducting polymers involves anion insertion associated to oxidation processes (p-type doping) and cation insertion coupled with reduction ones (n-type doping). Efficient polymer-based electronic devices require lowering of the redox potential of the involved electron transfer processes, and electrochemical reversibility is necessary to allow repetitive charge/discharge processes. In the... 

The properties of zeolites are decisively dependent on their cations, either on the framework cations introduced by replacement of Si or Al in the zeolite lattice or on the charge-compensating nonframework cations inserted by ion exchange in the solid state or from solutions. This opens possibilities for targeted modification of these materials in order to tailor their properties for specific applications. 

The size of the cations in PPy acmators was found to be a cracial factor, with a faster response given for smaller cations for cylindrical films formed in Nap-TS, showing that the bending mechanism was controlled by cation insertion and extraction [107]. For PPy films doped with [Fe(CN)e], a larger deformation was estabhshed with increased solvation of the alkali-metal cation used, in the order Li > Na > K [122]. This finding was confirmed in a further study using PPy(DBS) tubular films [104]. 

The scope of the present chapter is to discuss the properties and preparation of electroactive polymers with emphasis on high conductivity materials. Analogies to inorganic intercalation materials will be used to illustrate the thermodynamic properties of the polymers. Cation insertion may be distinguished from anion insertion by the influence of the solution... 

C. Barbero, M. C. Miras, B. Schnyder, O. Haas, R. Kotz, Sulfonated polyaniline films as cation insertion electrodes for battery applications. 1. Structural and electrochemical characterization, of Materials Chemistry 1994, 4,1775. 

Olah et al. have developed direct carbonylation of isoalkanes that lead to ketones in high conversion and high selectivity under HFiBFs catalysis. The chemistry is unlike the Koch reaction and involves activated formyl cation inserting directly into the C-H a-bond of isoalkanes, followed by strong acid-catalyzed rearrangement. 

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