Co3O4-doped two-dimensional carbon nanosheet as an electrode material for high-performance asymmetric supercapacitors

Transition metal oxide-doped two-dimensional (2D) carbon nanosheets are attractive for the preparation of supercapacitors. However, the synthesis of the composites involves complex steps and multiple reagents. Herein, we demonstrate a simple and effective method for the fabrication of 2D carbon nanosheets with highly dispersed cobalt oxide nanoparticles on their surface. Gelatin and melamine were used as the carbon sources, while cobalt acetate (Co(CH3COO)2) was used as the source of Co3O4. After the hydrothermal reaction and carbonization, Co3O4 was well anchored on the surface of the 2D carbon nanosheets. Interestingly, the morphology could be tuned by varying the amount of cobalt acetate added to the gelatin and melamine co-polymer. A 2D carbon nanosheet formed when more than 1 g of cobalt acetate was used along with 1 g of gelatin and 0.3 g of melamine has excellent electrochemical properties. When used in an asymmetric supercapacitor, high energy density, and long stability could be achieved, which is promising for the development of high-performance supercapacitors. •An efficient and environmentally benign carbonization protocol was established for the preparation of GM-C@Co3O4.•The morphology of the composite can be tuned by change the concentration of cobalt acetate in the precursor.•GM-C@Co3O4 composite exhibits superior electrochemical properties and stability.•GM-C@Co3O4 shows great promise as an electrode material for supercapacitors.