FeCo2S4/NH2-GQDs nanoflowers supported on Ni foam as novel binder-free electrode for high-performance supercapacitors

In this work, the ferric cobalt sulfide/aminated graphene quantum dots (FeCo 2 S 4 /NH 2 -GQDs) nanoflowers grown on Ni foam substrate have been successfully fabricated via a facile two-step hydrothermal method. The as-prepared FeCo 2 S 4 /NH 2 -GQDs nanoflowers can expose plenty of electroactive sites, provide fast charge transfer paths and buffer the drastic volume change during long-term charge–discharge cycles. Therefore, the FeCo 2 S 4 /NH 2 -GQDs nanoflowers exhibit excellent supercapacitive performance, including high specific capacitance, excellent rate capability and cycling stability. The specific capacitance of FeCo 2 S 4 /NH 2 -GQDs composite electrode reaches 2314.8 and 1802.5 F g −1 at the current density of 1 and 10 A g −1 , respectively, while maintaining superior cycling stability with 95.1% capacitance retention after 5000 cycles. This study proves that NH 2 -GQDs are promising materials to enhance the electrochemical performance of bimetallic sulfides, providing a new insight for the design and fabrication of novel electrode materials for high-performance supercapacitors.