Electrochemical copolymerization of N-methylpyrrole and 2,2 '-bithitiophene; characterization, micro-capacitor study, and equivalent circuit model evaluation

Abstract

N-methylpyrrole (N-MPy) and 2,2'-bithiophene (BTh) were electrocopolymerized in 0 center dot 2 M acetonitrile-sodium perchlorate solvent-electrolyte couple on a glassy carbon electrode (GCE) by cyclic voltammetry (CV). The resulting homopolymers and copolymers in different initial feed ratios of [N-MPy](0)/[BTh](0) = 1/1, 1/2, 1/5 and 1/10 were characterized by CV, Fourier-transform infrared reflectance attenuated transmittance (FTIR-ATR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and electrochemical impedance spectroscopy (EIS). The capacitive behaviours of the modified electrodes were defined via Nyquist, Bode-magnitude, Bode-phase and admittance plots. The equivalent circuit model of R(C(R)(QR)(CR)) was performed to fit theoretical and experimental data. The highest low-frequency capacitance (C (LF)) were obtained as C (LF) = similar to 1 center dot 23 x 10 (-4) mF cm (-2) for P(N-MPy), C (LF) = similar to 2 center dot 09 x 10 (-4) mF cm(-2) for P(BTh) and C (LF) = similar to 5 center dot 54 x 10 (-4) mF cm(-2) for copolymer in the inital feed ratio of [N-MPy](0)/[BTh] (0) = 1/2.