Protonic acids electrochemical characteristics

A rational analysis of filler effects on structural, proton transport properties and electrochemical characteristics of composite perfluorosulfonic membranes for Direct Methanol Fuel Cells (DMFCs) was reported [7]. It has been observed that a proper tailoring of the surface acid-base properties of the inorganic filler for application in composite Nafion membranes allows appropriate DMFC operation at high temperatures and with reduced pressures [7]. An increase in both strength and amount of acidic surface functional groups in the fillers would enhance the water retention inside the composite membranes through an electrostatic interaction, in the presence of humidification constraints, in the same way as for the adsorption of hydroxyl ions in solution [7]. 

In a subsequent study Devynck and co-workers81,82 studied the electrochemical oxidation of alkanes and alkenes in triflic acid monohydrate. The acidity of CF3SO3H H20 was found to be intermediate between that of aqueous acid media and superacidity. Alkanes undergo two-electron oxidation, whereas alkenes are protonated to yield carbenium ions in this medium. In addition to various transformations characteristic of carbenium ions [Eqs. (5.36)—(5.38)], they undergo a reversible disproportionation to give an alkane and an aldehyde [Eqs. (5.40)]. 

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... 

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