Synthesis of V-shaped MnO₂ nanostructure and its composites with reduced graphene oxide for supercapacitor...

A unique V-shaped MnO₂ nanostructure is synthesized with a weak acid (acetic acid) using the microwave-assisted hydrothermal technique. To improve the performance of MnO₂ in supercapacitor applications, its composite was prepared with reduced graphene oxide (rGO), i.e., MnO₂/rGO, with different weight ratios of MnO₂ and rGO. The specific capacitance values of the as-synthesized V-shaped MnO₂ nanostructure and MnO₂/rGO nanocomposite were calculated to be 64.75 and 88.95 F g^-1 at a current density of 0.5 A g^-1, respectively, in 1 M Na₂SO₄ electrolyte. Furthermore, a two-electrode asymmetric supercapacitor device was fabricated using the MnO₂/rGO nanocomposite as a positive electrode and activated carbon as a negative electrode. The device has shown energy densities of 25.14 and 17.95 W h kg^-1 at 0.25 and 1 kW kg^-1 power densities, respectively. These values suggest that the MnO₂/rGO nanocomposite is a promising material for supercapacitor devices.