Heterostructure arrays of NiMoO4 nanoflakes on N-doping of graphene for high-performance asymmetric supercapacitors

Supercapacitors, as a clean and sustainable power supply, have been a popular subject of research in the field of energy storage owing to their excellent electrochemical performance. As an important part of supercapacitors, electrode materials and structures have been continuously designed and improved. This study presents a facile synthesis of an N-doping of graphene/NiMoO4 (NG/NiMoO4) heterostructure for electrochemical supercapacitors. By combining excellent conductivity, large specific surface area of graphene, and reversible redox of metal oxide, this hybrid composite exhibits an ultrahigh specific capacitance of 1913 F/g at 1 A/g. Using NG/NiMoO4 as positive electrode and active carbon as negative electrode, an asymmetric supercapacitor was assembled. The device exhibits a high capacitance of 62.5 F/g at 0.5 A/g, a maximum energy density of 22.2 Wh/kg at the power density of 400 W/kg, and excellent cycling stability (94.2% retention after 5000 cycles). The results demonstrate that the NG/NiMoO4 composite is a promising electrode material for supercapacitors in energy storage applications.