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

N-methylpyrrole (N-MPy) and 2,2′-bithiophene (BTh) were electrocopolymerized in 0·2 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 (CLF) were obtained as CLF = ∼ 1·23 × 10−4 mF cm−2 for P(N-MPy), CLF = ∼ 2·09 × 10−4 mF cm−2 for P(BTh) and CLF = ∼ 5·54 × 10−4 mF cm−2 for copolymer in the inital feed ratio of [N-MPy]0/[BTh]0= 1/2.