Single and ternary nanocomposite electrodes of Mn3O4/TiO2/rGO for supercapacitors

Graphene (G) and ternary nanocomposites of Mn3O4, TiO2, and reduced graphene oxide(rGO) electrodes have been prepared for supercapacitor applications. The as-synthesized samples were characterized using several techniques including XRD, SEM, TEM, XPS, and Raman spectroscopy. Electrochemical characterizations were studied via cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). XRD patterns of TiO2 and Mn3O4 showed the formation of anatase and hausmannite tetragonal nanoparticles, respectively, whereas rGO and G showed an amorphous structure. The TEM analysis showed spherical shaped particles with less than 50 nm sizes for Mn3O4, nanotube for TiO2, fiber structure for rGO, and layered structure for graphene. The Mn3O4/TiO2/rGO ternary nanocomposite electrode presented a much higher specific capacitance than its single individual constituents. The ternary nanocomposite has a specific capacitance of 356 F g(-1) in 6 M KOH aqueous electrolyte and respectable cycling performance, with 91% capacitance retained over 3000 cycles referring to its suitability for supercapacitor applications. An asymmetric supercapacitor (ASC) was constructed using a Mn3O4-TiO2-rGO (MTrGO) as a positive electrode and G as a negative electrode. The organized (ASC) works steadily under the potential window of 0-1.8 V and provides a high-energy density of 31.95 Wh kg(-1) at a power density of 7188 W kg(-1) complemented by satisfactory cycle stability with 87% capacitance retention over 1000 cycles.