Comparison of electrolyte effects for poly(3,4- ethylenedioxythiophene) and poly(3-octylthiophene) by electrochemical impedance spectroscopy and polymerization parameters with morphological analyses on coated films

摘要

3,4-Ethylenedioxythiophene and 3-octylthi-ophene were electropolymerized on glassy carbon electrodes (GCE) to compare with four different electrolytes [lithium perchlorate (LiClO_4), sodium perchlorate, tetraethylammonium tetrafluoroborate, and tetrabutylammonium tetrafluoroborate] in a solvent of acetonitrile (CH_3CN). Modified electrodes were characterized by cyclic voltammetry, attenuated total reflectance-Fourier transform IR spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, atomic force microscopy, and electrochemical impedance spectroscopy (EIS). Nyquist and Bode plots for magnitude, phase, admittance, and capacitance on both polymer-modified electrodes were comparatively investigated in detail. The highest low-frequency capacitance (C_(LF)) and double-layer capacitance (C_(dl)) were obtained in 0.1 M LiClO_4/CH_3CN for poly(3,4-ethylenedioxythiophene) and poly(octylthiophene)/ GCE. EIS data were fitted to the equivalent circuit model of R(Q(R(C(R(C(RW))))))(CR), which is used to investigate circuit parameters.