As an ideal electrochemical energy storage candidate, supercapacitors have gained increasing attention due to high power density, long cycle life and fast charge/discharge rate, which is more suitable for large power components. Conventional lithium-ion batteries are widely used in portable electronic equipment such as laptop computers, cell phones and electric vehicles.

In this study, the graphene supported manganese (IV) oxide (MnO₂/GR), cobalt (II/III) oxide (Co₃O₄/GR) and manganese-cobalt oxide (MnO₂-Co₃O₄/GR) nanocomposites were synthesized using the microwave irradiation method. The synthesized composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical performance of the graphene supported MnO₂, Co₃O₄ and MnO₂-Co₃O₄ nanocomposites was evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge.

The graphene supported MnO₂-Co₃O₄ nanocomposites have significant influence on the electrochemical performance as compared with that of the MnO₂/GR and Co₃O₄/GR. The maximum specific capacitance of 152 F g^-1 was achieved at the MnO₂-Co₃O₄/GR in the 1 M Na₂SO₄ aqueous solution at the scan rate of 10 mV s^-1.

Acknowledgement

This research is funded by the European Social Fund under the No. 09.3.3-LMT-K-712-02-0142 “Development of Competences of Scientists, other Researchers and Students through Practical Research Activities” measure.