Electrolyte type and concentration effects on poly(3-(2- aminoethyl thiophene) electro-coated on glassy carbon electrode via impedimetric study

Abstract

In this study, 3-(2-Aminoethyl thiophene) (2AET) monomer was electropolymerized on glassy carbon electrode (GCE) using various electrolytes (lithium perchlorate (LiClO4), sodium perchlorate (NaClO4), tetrabutyl ammonium tetra fluoroborate (TBABF4) and tetraethyl ammonium tetra fluoroborate (TEABF4) in acetonitrile (CH3CN) as solvent. Poly(3-(2-aminoethyl thiophene) (P(2AET))/GCE was characterized by cyclic voltammetry (CV), Fourier transform infrared reflectance spectrophotometry (FTIR-ATR), scanning electron microscopy, energy dispersive X-ray analysis (EDX), and electrochemical impedance spectroscopy (EIS) techniques. The electrochemical impedance spectroscopic results were given by Nyquist, Bode-magnitude, Bode-phase, capacitance and admittance plots. The highest low frequency capacitance (C LF) value obtained was 0.65 mF cm−2 in 0.1 M LiClO4/CH3CN for the initial monomer concentration of 1.5 mM. The highest double layer capacitance (C dl = ~0.63 mF cm−2) was obtained in 0.1 M LiClO4/ACN for [2AET]0 = 0.5, 1.0 and 1.5 mM. The maximum phase angles (θ = 76.1o at 26.57 Hz) and conductivity (Y″ = 3.5 mS) were obtained in TEABF4/ACN for [2AET]0 = 0.5 and 1.0 mM, respectively. An equivalent circuit model of R(Q(R(Q(R(CR))))) was simulated for different electrolytes (LiClO4, NaClO4, TBABF4 and TEABF4)/P(2AET)/GCE system. A good fitting was obtained for the calculated experimental and theoretical EIS measurement results. The electroactivity of P(2AET)/GCE opens the possibility of using modified coated electrodes for electrochemical micro-capacitor electrodes and biosensor applications.