The synthesis of rGO/RuO2, rGO/PANI, RuO2/PANI and rGO/RuO2/PANI nanocomposites and their supercapacitors

Abstract

In this work, reduced graphene oxide (rGO) was obtained by chemical reduction of graphene oxide (GO) using sodium borohydride (NaBH4). Four different nanocomposites rGO/ruthenium oxide (RuO2), rGO/polyaniline (PANI), RuO2/PANI and rGO/RuO2/PANI were chemically synthesized. In addition, PANI-based nanocomposites were synthesized by in situ polymerization technique. Nanocomposites were examined by different methods such as Fourier transform infrared spectroscopy–attenuated transmission reflectance, UV–Vis spectrophotometer, scanning electron microscopy–energy-dispersive X-ray analysis, thermal analysis (TGA–DTA) and transmission electron microscopy. TGA–DTA results show that the decomposition of rGO/RuO2/PANI nanocomposite (27.2% at 788.8 °C) was less than that of rGO (1% at 779.7 °C), which confirms the successful synthesis of nanocomposites. These nanocomposites can be used in supercapacitor applications. Supercapacitor device performances were taken by cyclic voltammetry (CV), galvanostatic constant current and electrochemical impedance spectroscopy (EIS) via two-electrode configuration. Ragone plots were drawn to observe energy and power densities of supercapacitor devices. Stability tests were taken by CV method for 1000 cycles. A ternary rGO/RuO2/PANI nanocomposite yields higher specific capacitance as Csp = 723.09 F g−1 than rGO/RuO2 (Csp = 347.28 F g−1), rGO/PANI (Csp = 159.62 F g−1), RuO2/PANI (Csp = 40.2 F g−1) and rGO (Csp = 37.5 F g−1) at 2 mV/s by CV method. A new electrical circuit model of LR(C(R(CR))) was used to analyze EIS data for rGO, rGO/PANI, rGO/RuO2, RuO2/PANI and rGO/RuO2/PANI nanocomposites. These nanocomposites demonstrate remarkable properties for use as electroactive materials for supercapacitor applications.