Influence of the Supporting Electrolyte on the Electrochemical Polymerization of 3,4-Ethylenedioxythiophene. Effect on p- and n-Doping/Undoping, Conductivity and Morphology

摘要

A systematic study of the influence of the type of electrochemical perturbation, in the presence ofvarious salts, namely LiClO4, TBAClO4, TBAPF6, TEAPF6, LITFMS or TBATFMS in acetonitrile, onthe electropolymerization of 3,4-ethylenedioxythiophene on platinum was accomplished. Poly(3,4- ethylenedioxythiophene) (PEDOT) electrodeposits were electrochemically characterized in situ whileprepared by cyclic voltammetry and constant potential techniques from solutions containing themonomer and each of the abovementioned electrolytes. n- and p-doping/undoping processes(reversibility, stability and charge) and nucleation and growth mechanisms, that subsequently will becomplemented and compared using conductivity measurements (four point probe method) andmorphological characterization by SEM and AFM, were studied. It was verified that the volume of thesupporting electrolyte ions and the waveform applied for the electrosynthesis, correlate directly withconductivity, morphology and reversibility, charge and stability of the generated polymeric coatings.Considering its likely aplication for the development of batteries, assessing by potentiodynamic-1 method during 1000 cycles of charge/discharge in 0.10 mol L LiCl aqueous solution, it was finallycorroborated that films obtained from 5 voltammetric cycles in the presence of TBAPF6 are the mostsuitable candidates by showing, besides of reversibility, the greatest charge, with a stability larger than95%. In any case, the results of this study allow selecting the electrosynthesis working conditionsdepending on the wanted application of the PEDOT modified electrode.