Nucleation and growth mechanism for the electropolymerization of aniline in trifluoroacetic acid/lithium perchlorate/propylene carbonate medium

In the present work, the nucleation and growth mechanism for the electropolymerization of aniline in propylene carbonate medium containing 0.06 M trifluoroacetic acid and 0.05 M lithium perchlorate was investigated at different potentials on highly oriented pyrolytic graphite (HOPG) by potentiostatic current-time transients (i-t) and atomic force microscopic (AFM) measurements. The electrochemical data fitted with the theoretical curves for nucleation and growth suggest that the electropolymerization of aniline consists of progressive nucleation followed by 3D growth at an early stage and layer-by-layer growth in subsequent periods. The results obtained from transient analysis were in good agreement with the results of the AFM analysis. In our previous studies with aqueous solutions, we observed only progressive nucleation followed by a 3D growth mechanism for the electropolymerization of aniline in a higher potential range, 1.5-2.0 V vs. Ag/AgCl. Hence, the results obtained from the present work indicate that the nucleation and growth mechanism depends on the medium.