The characteristics of electrochemically produced polyaniline as the active material of secondary batteries were studied in aqueous electrolytes. The cell of the type,
normalZn/1M ZnSO4/normalpolyaniline
, has the maximum capacity of 108 Ah/kg and the energy density of 111 Wh/kg. The coulombic efficiency was close to 100% over at least 2000 complete cycles when cycled between 1.35V and 0.75V at a constant current of 1 mA cm−2. The
normalpolyaniline/4M H2SO4/PbO2
cell, where polyaniline was used as the anode, also showed excellent recyclability. The effect of oxygen and of the exposure to high anodic potential to the characteristics of polyaniline electrodes was also studied.
Electrocatalytic oxidation of methanol on Pt modified polyaniline electrodes was investigated with the aim of developing highly active composite electrodes for direct methanol fuel cells. Cyclic voltammetry and chronoamperometry were used to evaluate the catalytic activity in sulfuric acid solutions containing methanol. Pt / polyaniline modified carbon electrodes showed higher catalytic activity towards oxidation of methanol than Pt deposited carbon electrodes. The effect of different protonic acids used in the electrochemical preparation of polyaniline on the oxidation current of methanol was studied. Largest oxidation current was obtained for polyanilines prepared in sulfuric acid solutions.
Basic behaviors and properties of polyaniline(PA) deposited anodically on platinum electrodes have been studied on the following points. 1) Effect of the mode of electrolysis and supporting electrolytes in the film forming process. 2) Characteristics of charging-discharging processes. 3) Electric conductivity and elemental composition of PA. The different modes of electrolysis do not affect the characteristics of the PA electrode obtained. The growth rate of PA film is 2.7–2.8 times faster in sulfuric acid than in perchloric, nitric or hydrochloric acid. It is indicated that there are two types of doping; one is associated with the acid-base equilibrium between amino or imino group in the film and proton in the solution and the other is associated with the excess charge in the film produced by anodic oxidation. The electric conductivity of PA markedly decreases by the immersion in alkali solutions. The release of doped anion from PA by treating with an alkali solution is confirmed by the elemental analysis. The amount of anions occluded by the electrochemical doping process is determined to be 0.25–0.29 per monomer unit.
Intermolecular hydrophosphination of alkynes with diphenylphosphine is catalyzed by a Yb[bond]imine complex, [Yb(eta(2)-Ph(2)CNPh)(hmpa)(3)], to give alkenylphosphines and phosphine oxides after oxidative workup in good yields under mild conditions. This reaction is also applicable to various carbon[bond]carbon multiple bonds such as conjugated diynes and dienes, allenes, and styrene derivatives. Regio- and stereoselectivity and the scope and limitation of the present reaction clearly differ from those of the corresponding radical reaction. Instead, the reaction takes place through insertion of alkynes to a Yb[bond]PPh(2) species, followed by protonation. In fact, the Yb[bond]phosphido complex, [Yb(PPh(2))(2)(hmpa)(3)], is obtained from the imine complex and phosphine, which exhibits similar catalyst activity for the hydrophosphination. The empirical rate law is nu = k[catalyst](2) [alkyne](1)[phosphine](0) at least under the standard conditions.
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