Electrochemical polymerization of indolе on the surface of the tin (IV) oxide

Abstract

Polyindole is an important electroactive polymer that can be obtained by electrochemical or chemical oxidation of indole. The indole polymer has the ability to change the spectrum and, accordingly, the color, under the action of the applied potential. For practical use of this polymer, it is advisable to obtain it in the form of a thin film on the surface of the optically transparent electrode. The purpose of the work was the study of the features of the electrochemical polymerization of indole on the surface of the tin oxide SnO 2 electrode. The conditions of obtaining thin layers of polyindole on the surface of SnO 2 electrode in organic medium were investigated by method of cyclic voltammetry. For research, we used an electrochemical 3-electrode cell in which the working electrode was a glass plate covered with a SnO 2 conductive layer, the comparison electrode – Pt wire, the counter electrode – platinum plate. The polymerization was carried out in 0.1 M indole solution in 0.05 M TBAP in acetonitrile that was used as the supporting electrolyte. It was established that the еlectrochemical polymerization of indole in the potential range E = – 0.2 ... 1.7 V is accompanied by the formation of an electroactive polymer layer, with the intensity of the peaks of oxidation – reduction currents increase with the number of sweep cycles. The absorption maximum at 390 nm, 500 nm and 860 nm are observed in the optical spectra of the polyindole film, which correspond to the electronic transitions in the conjugated polymer systems. On the basis of the obtained data, we proposed a possible scheme of initiation of electrochemical polymerization of indole. Keywords: polyindole, cyclic voltammetry, electrochemical polymerization, spectroscopy, SnO 2 electrode.