Electroactive polymer/graphene oxide nanostructured composites; evidence for direct chemical interactions between PEDOT and GOx

• Nanostructured composites based on pEDOT and graphene oxide (GOx) were synthesized.
• A new chemical bond between S from thiophene rings and O from GOx was detected.
• PEDOT/GOx nanocomposites exhibit compact layered structure.
• Significant improvement of electric capacitance was noticed for nanocomposites.

This work concerns electrochemical synthesis of nanocomposites consisting of conducting polymer and reduced graphene oxide (rGOx) as electrode materials for supercapacitors. The electrosynthesis was performed in an aqueous solution of the 3,4-ethylenedioxytiophene (EDOT) monomer and graphene oxide (GOx) without supporting electrolyte. The amount of GOx was optimized to obtain the best electrochemical performance of the nanocomposite material. The just-prepared nanocomposite (pEDOT/GOx) was electrochemically reduced in order to decrease the number of oxygen-rich functional groups on the GOx surface, to increase the amount of sp2 hybridized carbon atoms and, in consequence, to increase the electrical conductivity. SEM results show a uniform, wavy and layered structure of the nanocomposite. XPS analysis confirms a partial reduction of functional oxygen groups of GOx and a partial return to the graphene-like sp2 network in the process of electrochemical reduction. A new chemical bond has been detected between sulphur from thiophene rings and oxygen coming from graphene oxide as proof of direct chemical interaction between both components PEDOT and GOx. Electrochemical tests show that the polymer provides an excellent conductive matrix for the graphene oxide. The incorporated graphene oxide, on the other hand, improves the nanocomposite specific surface area. As a result, the nanocomposite exhibits much higher electric capacitance in comparison with the pure polymer or graphene oxide alone. Nanocomposites display fast charging/discharging processes and good electrochemical stability. The electrochemical properties put them in a promising position as a potential material for energy storage devices such as supercapacitors.