Synthesis and characterization of MnO2-decorated graphene for supercapacitors

We report the simple one-step synthesis of a reduced graphene oxide–manganese oxide (rGO-MnO2) nanocomposite using graphene oxide (GO) and KMnO4 in the presence of sulfuric acid. The crystal structure, morphology, thermal, pore size, and other physical properties of the rGO-MnO2 nanocomposite were systematically analyzed by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller analysis. XPS analysis confirmed the synthesis of exfoliated GO and rGO-MnO2 nanocomposite. The rGO-MnO2 nanocomposite exhibited a maximum specific capacitance, energy, and power density of 290 F g−1, 25.7 Wh kg−1, and 8008.7 W kg−1, respectively, in a 1M Na2SO4 electrolyte, and a high retention (87.5%) of capacitance after 5000 cycles. The enhanced electrochemical properties are caused by good contact between MnO2 nanorods and graphene nanosheets, and the higher conductive and capacitive behavior of graphene.