Templateless Electrosynthesis of Nanostructured PEDOT Films

Abstract

Conducting polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) have been widely used as electrode materials for supercapacitors. PEDOT is a promising electrode material because of its high electrical conductivity, great environmental stability and high cycling stability. Nanostructuration of the polymers can provide better performances of volumetric swelling and shrinking during charge/discharge processes. We have already described the templatefree electrosynthesis of PPy nanostructures [1-3] but to the best of our knowledge, the easy templateless electrosynthesis of nanostructured PEDOT in aqueous solutions has not been reported yet. This work demonstrates a simple one-step templatefree electrosynthesis method of preparing various structured PEDOT films which show good specific capacitance and cycling stability. By varying some experimental parameters, we have obtained various nanostructures: nanofiber networks, nanorods, nanospheres and nanowires of PEDOT (Figure 1, SEM micrographs of various morphologies of PEDOT obtained using a templateless electrochemical route.). These structures were obtained by simply adjusting the applied potential and the composition of the monomer solution i.e. the concentration of weak-acid anions such as HPO4 2- and the concentration of non-acid anions such as ClO4 -. The growth mechanism of the nanostructured PEDOT films will be discussed. At the very beginning of the process, water oxidation takes place which leads to the formation of hydroxyl radicals and to the evolution of O2. Moreover, the nanostructured PEDOT films show high specific capacitance (~100-200 F/g) and cycling stability (capacitance retention is about 90% after 1000 scans). Therefore, the nanostructured electrogenerated PEDOT films could be used for many applications, such as supercapacitors.