Synthesis of novel graphene/Co3O4/polypyrrole ternary nanocomposites as electrochemically enhanced supercapacitor electrodes

A novel graphene (Gr)/Co3O4/polypyrrole (PPy) ternary nanocomposite (GCP) was synthesized by a two-step technique in which the surface of Gr/Co3O4 binary nanocomposite (GC) was covered by a conductive thin film of PPy. First, Co3O4 anchoring nanoparticles were embedded into graphene sheets by a chemical precipitation method, and then covered by a PPy thin film via in-situ polymerization. The fabricated nanocomposites were cast on the Cu/Cu(OH)2 substrates prepared by soaking in an alkaline solution. Electrochemical evaluations of the GCP nanocomposite in a three-electrode system show a high specific capacitance of 422 F g−1 at a scan rate of 10 mV s−1 and 385 F g−1 at a current density of 1 A g−1 in 6 M KOH. Moreover, the energy density of 13.4 Wh kg−1 is obtained at the power density of 250 W kg−1. The enhanced electrochemical performance of the GCP nanocomposite is originated from the synergistic effect of its three components. Eventually, a full GCP||GCP symmetric supercapacitor cell in an organic electrolyte (1 M TEA-BF4 in acetonitrile) was also tested and the results showed that maximum specific capacitance, voltage window, and energy density are 33.06 F g−1, 2 V, and 18.36 Wh kg−1 at 10 mV s−1, respectively.