Poly(3,4-Ethylenedioxypyrrole) Enwrapped by Reduced Graphene Oxide: How Conduction Behavior at Nanolevel Leads to Increased Electrochemical Activity

Composite films of poly(3,4-ethylenedioxypyrrole) (PEDOP) enwrapped by reduced graphene oxide (RGO) and flanked by an ionic liquid (IL: dialkyl substituted imidazolium imide) have been synthesized. To study the effect of functionalized RGO on the polymer, the structure, conduction properties, and redox chemistry of the PEDOP-RGO/IL composite films have been compared with that of the control PEDOP-IL film, doped only by the ionic liquid imide anion. Evidence for the successful inclusion of RGO/IL in PEDOP was obtained by X-ray photoelectron spectroscopy and high resolution transmission electron microscopy, in the form of modified C1s signals, new signals due to nitrogen and sulfur, and also the revelation of a quasi-hexagonal assembly of atoms in the RGO/IL nanosheets. Conductive-atomic force microscopy revealed the role of RGO/IL in completely modifying the charge carrying ability of PEDOP, as unusually high current values and a largely uniform current distribution were achieved in the PEDOP-RGO/IL composite in contrast to control PEDOP-IL. Point contact I – V profiles showed that the population of insulating domains flanking the conducting polymer grains is drastically reduced on replacing the IL dopant with RGO/IL in PEDOP. A reduced Fermi edge to valence band gap, an exemplary electrochromic coloring efficiency of 477 cm 2 C –1 (λ max = 509 nm), a 2-fold increment in dc electronic conductivity, improved switching kinetics, an amplified charge insertion–extraction capacity, as opposed to the case for control film, mirrored the role of RGO/IL in controlling the charge transport dynamics of PEDOP. The results show that the entrapping of a conducting polymer by RGO based nanostructures affords tunable redox, electronic and optical properties, thus providing a paradigm for mapping the current distribution in similar nanocomposites.