Poly(3,5-dithiophene-2-yldithieno[3,2-b;2′,3′-d]thiophene-co-Ethylenedioxythiophene)/Glassy Carbon Electrode Formation and Electrochemical Impedance Spectroscopic Study

Abstract

3,5-Dithiophene-2-yldithieno[3,2-b;2',3'-d]thiophene (Thy2DTT) and ethylenedioxythiophene (EDOT) were electro-copolymerized on glassy carbon electrode (GCE) in 0.1 M sodium perchlorate (NaClO4)/acetonitrile (ACN)/dichloromethane (CH2Cl2) (8:2) solution. Poly(Thy2DTT-co-EDOT)/GCE thin film was characterized by various techniques, such as Cyclic Voltammetry (CV), Fourier Transform Infrared Spectroscopy – Attenuated Transmittance Reflectance (FTIR-ATR), Scanning Electron Microscopy - Energy Dispersive X-ray analysis (SEM-EDX) and Electrochemical Impedance Spectroscopy (EIS). The effects of monomer mole fractions (mole fraction, XThy2DTT = nThy2DTT/nEDOT + nThy2DTT) (0.5, 0.66 and 0.83) during the preparation of modified electrodes were examined by EIS. Capacitive behaviors of the modified GCE were defined via Nyquist, Bode-magnitude, Bode-phase and Capacitance plots. The circuit model was used to fit the theoretical and experimental data through Kramers-Kronig Transform test. The lowest frequency capacitance (CLF) value was obtained as CLF = 0.89 mFcm−2 for poly(Thy2DTT). However, the highest CLF was obtained for the copolymer as CLF = 1.11 mFcm−2 for XThy2DTT = 0.66 and 0.83. Potential application of the copolymer could be energy-storage devices.