Electrochemical synthesis of some composites based on polypyrrole and poly(3,4-ethylenedioxythiophene) and investigation of their supercapacitor properties

In this thesis, some composites based on polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) were electrochemically synthesized on a pencil graphite electrode (PGE) surface as the electrode material to be used in supercapacitor applications, which can be an alternative to existing energy storage systems. In the first part of the thesis, CoHCF-fMWCNT composite was prepared from cobalt hexacyanoferrate (CoHCF) and carboxyl functionalized multi-walled carbon nanotube (fMWCNT). The PPy−CoHCF-fMWCNT composite was deposited on the PGE surface with the cyclic voltammetry (CV) technique in an aqueous solution containing CoHCF-fMWCNT, pyrrole (Py) monomer, and (±)-10-camphorsulfonic acid (HCSA). In the second part of the thesis, PEDOT−MO composites were prepared on the PGE surface in an aqueous medium containing 3,4-ethylenedioxythiophene (EDOT), HCSA, sodium dodecylbenzenesulfonate (SDBS), and various nanostructured metal oxide powders (MO) (CeO2, Co3O4, CoFe2O4, TiO2, ZrO2). The coatings were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR) methods. The supercapacitor properties of the prepared coatings were investigated in 0,5 mol L−1 H2SO4 solution by using CV, electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) techniques. It was determined that the addition of CoHCF-fMWCNT composite increased the specific capacitance (Cm) value of PPy from 431.6 F g−1 to 495.0 F g−1 at a current density of 5 A g−1. The specific capacitance of PEDOT, PEDOT−CeO2, PEDOT−Co3O4, PEDOT−CoFe2O4, PEDOT−TiO2, and PEDOT−ZrO2 coatings was calculated as 90.9 F g−1, 112.2 F g−1, 117.7 F g−1, 111.6 F g−1, 111.8 F g−1, and 112.0 F g−1, respectively, at a current density of 5 A g−1. Keywords: Composite, Electrochemical Polymerization, Poly (3,4-Ethylenedioxythiophene), Polypyrrole, Supercapacitor