A High Performance Supercapacitor Based on Graphene/Polypyrrole/Cu2O-Cu(OH)(2) Ternary Nanocomposite Coated on Nickel Foam

摘要

A simple and low-cost electrochemical deposition method is used to prepare reduced graphene oxide/polypyrrole/Cu2OCu(OH)(2) (RGO/PPy/Cu2OCu(OH)(2)) ternary nanocomposites as the electrode material for supercapacitor application. First, graphene oxidepolypyrrole (GO/PPy) nanocomposite is electrochemically synthesized on Ni foam by electro-oxidation of pyrrole monomer in an aqueous solution containing GO and Tiron. Subsequently, the GO/PPy film is converted to the corresponding reduced form (RGO/PPy) by an effective and eco-friendly electrochemical reduction method. Then, a thin layer of Cu2OCu(OH)(2) is formed on RGO/PPy film by chronoamperometry. The RGO/PPy/Cu2OCu(OH)(2) nanocomposite is characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), atomic force microscopy (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectra (FT-IR). SEM images show that Cu2OCu(OH)(2) nanoparticles are dispersed on the surface of RGO/PPy film with an average particle size of 5070 nm. The electrochemical performance of the as-prepared electrode is evaluated by various electrochemical methods using cyclic voltammetry, galvanostatic chargedischarge, and electrochemical impedance spectroscopy (EIS) in 0.5 M Na2SO4 solution. In the three-electrode system, RGO/PPy/Cu2OCu(OH)(2) exhibits an excellent gravimetric specific capacitance of 997 F g(1) at a current density of 10 A g(1), which is far better than GO/PPy (500 F g(1)), RGO/PPy (685.5 F g(1)), and GO/PPy/Cu2OCu(OH)(2) (750F g(1)). The utilization of the electrical double layer capacitance (EDLC) of graphene together with the pseudocapacitive behavior of PPy and Cu2OCu(OH)(2) leads to a maximum energy density of 20 Wh kg(1) at power density of 8000 W kg(1) and a maximum power density of 19 998.5 W kg(1) at an energy density of 5.8 Wh kg(1) for symmetric RGO/PPy/Cu2OCu(OH)(2) supercapacitor. Furthermore, RGO/PPy/Cu2OCu(OH)(2) nanocomposite maintains about 90% of the initial capacitance value after 2000 cycles.