Fabrication of sodium and MoS2 incorporated NiO and carbon nanostructures for advanced supercapacitor application

Transition metal oxides and carbonaceous nanocomposites have triggered enormous interest in the application of high-performance supercapacitors due to the outstanding electrical conductivity and superior theoretical capacitance. In this study, we prepared highly porous nanostructured NiO/C yolk-shell nanocomposites via a simple calcination of nickel-based metal-organic frameworks. The porosity and electrochemical property were further enhanced by incorporating sodium and hierarchical MoS2 nanostructures via a facile hydrothermal method. It was found that the as-synthesized Na-doped MoS2@NiO/C nanocomposites with hierarchical porosity exhibited superior electrochemical performance. Particularly, the delivered electrochemical capacitance of NiO/ C yolk-shell structure was 1779.50 F g-1 in an aqueous electrolyte (2 M KOH), and a superior specific capaci-tance of 2540.63 F g-1 was acquired after the incorporation of sodium and 2D layered MoS2 into the nano -composite. When a symmetrical supercapacitor was fabricated, a remarkable energy density of 36.93 Wh kg-1 was recorded in an environmental-friendly aqueous-based electrolyte. More significantly, the outstanding delivered capacitance retention and coulombic efficiency were 111.92 % and 97.6 %, respectively after 4000 continuous GCD cycles. Hence, the Na-doped MoS2@NiO/C with hierarchical porous nanostructures and extraordinary electrochemical performance was explicitly demonstrated in this study and can be utilized as electrode active materials in realizing high-performance supercapacitors.

Automated summary

Transition metal oxides and carbonaceous nanocomposites have been widely studied for high-performance supercapacitors. In this study, highly porous nanostructured NiO/C yolk-shell nanocomposites were prepared by calcination of nickel-based metal-organic frameworks, and the porosity and electrochemical property were further enhanced by incorporating sodium and hierarchical MoS2 nanostructures. The Na-doped MoS2@NiO/C nanocomposites showed superior electrochemical performance, achieving a specific capacitance of 2540.63 F g-1 and an energy density of 36.93 Wh kg-1 in an aqueous-based electrolyte. The excellent capacitance retention and coulombic efficiency after 4000 cycles make this material promising for high-performance supercapacitors.