In situ time-resolved Raman spectroelectrochemical study of aniline polymerization at platinum and gold electrodes

A comparative in situ time-resolved Raman spectroelectrochemical study on aniline polymerization at platinum, smooth gold, and roughened gold electrodes was performed with 785 nm laser excitation. Under the constant anodic current density electrolysis performed at the platinum electrode, the intensity of Raman bands grows continuously reaching a steady state within 8-10 min. At the smooth gold electrode, the maximum intensity is observed in a few or few tens of seconds, and appears to be ca. 1.5 orders of magnitude higher than for the platinum one. At the roughened gold electrode, again, a fast growth of intensity is observed, being ca. 3 orders higher than for the platinum one. After a prolonged electrolysis of ca. 150-200 mC/cm(2), the intensities for all three electrodes appear to be of a similar intensity. The results obtained show a strong surface enhancement of Raman spectra at the gold electrode, a very strong at the roughened gold one, and no enhancement at the platinum electrode at the beginning of electrooxidation, turning into a regular Raman scattering at a prolonged electrolysis, sufficient for the formation of a stable layer of polyaniline at the electrode surface.