Electrochemical synthesis and characterization of nanocomposites based on poly(3,4-ethylenedioxythiophene) and functionalized carbon nanotubes

• Nanocomposites based on conducting polymer and carbon nanotubes CNTs were obtained.
• Advantages of an electrochemical synthesis method of nanocomposites are presented.
• Functionalization of CNTs influences electrochemical properties of nanocomposites.
• Significant improvement of electric capacitance was noticed for nanocomposites.
• Capacitance values depend on amount of carbon nanotubes in the polymer matrix.

This work is focused on new composite materials consisting of poly(3,4-ethylenedioxythiophene) (pEDOT) and functionalized multi-walled carbon nanotubes synthesized electrochemically. Three types of composites were synthesized: the first one containing carbon nanotubes with carboxyl groups (covalent functionalization), the second one containing oxidized carbon nanotubes ox-MWCNTs (with different oxygen-rich polar groups) (covalent functionalization) and the third one containing carbon nanotubes dispersed using surfactant (non-covalent functionalization). The presence of oxygen moieties attached to carbon nanotubes decreases their hydrophobicity and helps to suspend them more uniformly in a solution used for electrosynthesis than the surfactant addition. Homogenous dispersion of carbon nanotubes and their amount in the synthesis solution is crucial for reproducibility and electrochemical properties of the composite layers. Thin nanocomposite films were tested electrochemically for supercapacitor application. Detailed surface investigation of the electrode layers by X-ray photoelectron spectroscopy shows differences in the chemical composition between the composites and the pure polymer. Moreover, electrochemical results show that the presence of carbon nanotubes with carboxyl groups in the polymer matrix may double the capacitance values compared to pure pEDOT.