Electrochemical copolymerization of carbazole and 2,2′:5′-2″ terthiophene: characterization and micro-capacitor application

In this paper, a copolymer of carbazole (Cz) and 2,2′:5′,2″-terthiophene (TTh) was electropolymerized in 0.1 M sodium perchlorate (NaClO4)/acetonitrile (CH3CN) on glassy carbon electrode. The optimum conditions of resulting homopolymers of Cz, TTh and copolymer of Cz and TTh in the initial feed ratio of [Cz]0/[TTh]0 = 1/10 were characterized by cyclic voltammetry, Fourier-transform infrared-attenuated total reflectance, scanning electron microscopy, energy dispersive X-ray analysis, and electrochemical impedance spectroscopy. Morphological analysis of copolymer shows that a micro-spherical and web-like morphology was formed for copolymer at different initial feed ratios of [Cz]0/[TTh]0 = 1/2, 1/5 and 1/10. The capacitive behavior of the modified electrodes was defined via Nyquist, Bode-magnitude, and Bode-phase plots. The highest low-frequency capacitance (CLF) was obtained as 4.11 mFcm−2 in the initial feed ratio of [Cz]0/[TTh]0 = 1/10. Double-layer capacitance (Cdl) and phase angles (θ) were obtained for homopolymer and copolymer systems. The highest Cdl was obtained as 2.01 mFcm−2 for the copolymer in the initial feed ratio of [Cz]0/[TTh]0 = 1/2. The highest phase angle of copolymer was obtained as θ = ~75° in the initial feed ratio of [Cz]0/[TTh]0 = 1/1. These capacitance results confirmed that films of copolymer Cz/TTh are promising materials for micro-capacitor applications.