Nucleation and growth of poly(3,4-ethylenedioxythiophene) in acetonitrile on platinum under potentiostatic conditions

The electrodeposition mechanisms of 3,4,-ethylenedioxythiophine (EDOT) were studied according to electrocrystallization theory. The analyis of the chr onoamperograms indicated that the initial stage of the electrodeposition wa s a combination of instantaneous 2-D and instantaneous 3-D mechanisms since the electrodeposition was carried out under charge transfer control rather than diffusion. In the later stages, layer-by-layer growth mode in accorda nce with the Stranski-Krastanov model was observed. Our results shown a var iation of the anodic transfer coefficient as a function of monomer concentr ation. Under our experimental conditions, the growth rate constant of the 2 D nucleus and the growth perpendicular to the surface rate constant did not depend upon potential beyond a monomer concentration of 0.15 mol l(-1). Th e quasi-metallic behaviour of oxidized poly(3,4-ethylenedioxythiophene) (PE DOT) was analyzed according to Feldberg's model. A Feldberg parameter of 0. 61 V-1 was obtained. The stability of PEDOT was studied during successive p olarization between - 0.6 and 0.5 V at a scan rate of 0.2 V s(-1) in aceton itrile and in aqueous solutions containing tetrabutylammonium perchlorate a nd lithium perchlorate as electrolyte. About 86 and 66% of the electrochemi cal activity were retained after polarization for 1200 cycles in acetonitri le and aqueous solutions, respectively. These results indicated the good st ability of the thin film of PEDOT on the electrode surface. (C) 1999 Elsevi er Science S.A. All rights reserved.