Electrosynthesis of Poly(3-dodecyl thiophene) in Acetonitrile with Boron Trifluoride Diethyl Etherate: The Effect of the Electrolyte on Electrochemical Impedance and Morphology

Abstract

3-dodecylthiophene (3-dth) was electropolymerized onto platinum wire (Pt) in acetonitrile (ACN) containing different percentages of boron trifluoride diethyl etherate (BFEE) by using cyclic voltammetry (CV). The oxidation potential of the monomer was decreased by adding BFEE in ACN. The monomer was oxidized in pure BFEE at 0.78 V. The thickness of the film was reached to maximum value for 40% BFEE. Electrochemical impedance spectroscopy (EIS) measurements and Equivalent Circuit Modeling (ECM) were performed on the Pt/Poly (3-dth)/electrolyte system. The specific capacitance (Csp) value increased while the charge transfer resistance (Rct) value decreased with the increasing of concentration of BFEE. Rct value was 62.68 Ωcm2 for 100% BFEE. The highest Csp, 0.007 μFcm−2, and double layer capacitances (Cdl), 269 μFcm−2, were obtained for the film obtained in 100% BFEE. The inclusion of BFEE in the polymer structure was confirmed by Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR). Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to investigate the polymer film deposited onto substrate in terms of morphology. The pore resistance (Rp) value was decreased with increasing the concentration of BFEE. As result of this the roughness of the polymer surface was decreased due to the decreasing of porous structure.