Reduced graphene oxide grafted by the polymer of polybromopyrroles for nanocomposites with superior performance for supercapacitors

Abstract

An integrated structure has been designed by grafting the polymer of polybromopyrroles (PPBP) onto reduced graphene oxide (RGO) to produce RGO/PPBP nanocomposites with superior electrochemical performance for supercapacitors. The RGO/PPBP nanocomposites are featured with a high nitrogen content (>9 at%), enhanced degree of graphitization, improved specific surface area, abundant micropores, and a tunable hierarchical structure on the basis of sample characterization by XRD, Raman, FT-IR, XPS, SEM, high-resolution TEM, BET, and scanning probe microscopy (SPM) techniques. The grafting of PPBP onto RGO not only suppresses agglomeration and restacking of RGO but also tailors the growth of PPBP on RGO, producing a developed hierarchical structure beneficial for mass/charge transfer. The synergistic effect between RGO and PPBP ensures superior electrochemical performance of RGO/PPBP. In a three-electrode mode, the typical RGO/PPBP electrode presents a galvanostatic capacitance (C_g) of 256 F g⁻¹ at a current density of 10 A g⁻¹, with a capacitance retention of 99.2% after 10 000 cycles in 1 mol L⁻¹ H₂SO₄. More significantly, the typical RGO/PPBP‖RGO/PPBP supercapacitor cell exhibits a high C_cell value of 68 F g⁻¹ at 5 A g⁻¹, with a capacitance retention of 91.9% after 10 000 cycles. Also, relatively high energy density values of 13.6, 9.4, and 6.7 W h kg⁻¹ with the corresponding power density of 0.5, 2.5, and 10 kW kg⁻¹ are achieved, enabling the tested cell to stay at the high level for carbon-based supercapacitors with an aqueous electrolyte.