Monomer Concentration Effects of Poly (3-methylthiopene) on Electrochemical Impedance Spectroscopy

Abstract

Poly(3-methylthiophene) (PMT) doped with perchlorate anion was prepared electrochemically in the presence of sodium perchlorate (ClO4-) salt as the supporting electrolyte. The effect of current density, various initial monomer concentrations (0.1, 0.2, 0.5 M) and electrochemical impedance spectroscopy (EIS) on polymer films has been investigated. Cyclic voltammetry of PMT has been examined on carbon fiber microelectrode (similar to 7 mu m radius) in 0.1 M acetonitrile medium containing NaClO4 in the range of 0.0 to 2.0 V versus Ag in the presence and absence of 3-methylthiophene. Thin films were characterized by Fourier transform infrared - attenuated transmission reflectance (FTIR-ATR) spectroscopy and scanning electron microscopy (SEM). SEM revealed a globular, branched and fibrous morphology of poly(3-methylthiophene). After surface modification of carbon fiber microelectrode (CFME), capacitance properties were checked by using electrochemical impedance spectroscopy. Capacitive behaviors of coated CFMEs were defined via Nyquist plot, Bode magnitude plot, Bode - phase definitions; besides, conductance of modified microelectrodes was studied with Admittance plot. PMT / CFME exhibits high specific capacitance of similar to 4.12 F g(-1) in the initial monomer concentration of 0.1 M, in comparison with a value of similar to 3.75 F g(-1) for 0.2 M and similar to 2.32 F g(-1) for 0.5 M.