In situ EPR/UV-VIS spectroelectrochemistry of polypyrrole redox cycling

The redox behaviour of polypyrrole layers prepared by the electrochemical o xidation of pyrrole in acetonitrile solutions was studied using in situ EPR /UV-VIS spectroelectrochemistry. Various supporting electrolytes: p-toluene sulfonic acid, tetrabutylammonium perchlorate (TBAP) and tetraethylammoniu m p-toluene sulfonate (TEATos), were used. Optically transparent indium tin oxide (ITO)-coated glass and gold mesh electrodes were used as electrode m aterials. Using the calibrated manganese EPR standard, the quantitative tim e dependences of the three oxidation states in the polymer layer were obtai ned during redox cycling. The separation of the superimposed UV-VIS spectra was carried out by a least-squares method. The different mechanisms of the polymer oxidation, the polaron/bipolaron route and polaron/dimer route, ar e compared.