Simultaneous observation of the electropolymerisation process of conducting polymers by surface plasmon resonance spectroscopy, surface plasmon enhanced light scattering and cyclic voltammetry

In this study, we report the combined use of surface plasmon resonance spectroscopy (SPR) and cyclic voltammetry to investigate the electropolymerization process of aniline onto a gold electrode in situ. Electropolymerization of aniline was achieved by applying a cycling potential known from cyclic voltammetry monitored by SPR simultaneously. The potential cycling resulted in an oscillation of the SPR kinetic reflectivity curve. The time differential SPR kinetic reflectivity curve was correlated with the cyclic voltammogram at higher potential. At lower potential, a large difference between the SPR kinetic reflectivity curve and the cyclic voltammogram was observed. It is shown that this difference is caused by scattered light enhanced by the SPR and is due to the change of the optical refractive index at the polyaniline/electrolyte interface. The technique promises to be an important tool in determining the mechanism for the electropolymerization processes of conducting polymers.