Decoupling electrochemical parameters of molecular-level-controlled polypyrrole and graphene oxide nanocomposite

Abstract

A molecular-level-controlled polypyrrole from a predoped two-monomer-connected precursor (TMCP) and graphene oxide (GO) nanocomposite is synthesized for an active electrode. TMCP (Py:NDSA:Py) consists of two pyrrole monomer, in which bifunctional naphthalene disulfonic acid (NDSA) acts as a protonic dopant and connector. Four molecular-level-controlled P(Py:NDSA:Py)/GO-based nanocomposites are formed when Py:NDSA:Py is polymerized on the hydrophilic GO surface with 100, 75, 50, and 25 mol % of NDSA. The resulting P(Py:NDSA100:Py)/GO nanocomposite exhibits excellent electrochemical performance and cycling stability. A systematic investigations of molecular-level-controlled P(Py:NDSA100:Py)/GO nanocomposite shows that various parameters such as relatively high crystallinity (47.2 %), crystalline domain size (24.2 nm), high doping level (35 %), and electrical conductivity (23.6 S/cm) could be well controlled using a 100 mol % of NDSA connector. An optimized P(Py:NDSA100:Py)/GO nanocomposite with 20 wt% GO significantly improves the specific capacitance of 306 F g−1 at a current density of 1 A g−1 and excellent cycling stability of 75 % up to 2000 cycles without using carbon supplement (carbon black). This systematic decoupling of electrochemical parameters of molecular-level-controlled polypyrrole nanocomposites can serve as an approach for rational design with tailored properties of other polymeric nanocomposites for electrochemical applications.