Electrocatalytic synthesis of polyaniline on non-noble metal electrodes

Abstract

Electrochemical synthesis (ES) of polyaniline (PAn) at the surface covered by an oxide film is realized at a significantly higher voltage than is needed for the formation of a nonoveroxidized polymer. The involvement of catalytic amounts of the salts of transition metals in ES of PAn essentially facilitates the process at Ti, Ta, Pb, Al and stainless steel electrodes. IrCI2−6 anion was found to be an effective catalyst. During ES, IrCI2−6 forms a complex with aniline, where IrIY oxidizes aniline to a radical cation. The formation of radical cation is a limiting stage ES PAn. It is realized in a moment in the presence of IrCI2−6, thus providing a significant decrease of the induction period at a potentiostatic synthesis and the lowering of a working potential at a galvanostatic synthesis. It is shown that the composition of the complex includes IrIII and 2 aniline molecules, which form a paramagnetic dimer inside a coordination sphere. © 1997 John Wiley & Sons, Ltd.