Dual functionalized Fe2O3 nanosheets and Co9S8 nanoflowers with phosphate and nitrogen-doped carbon dots for advanced hybrid supercapacitors

The development of novel electrode materials with admirable electrochemical behaviors is a new opportunity to meet the current demand for the high energy density of supercapacitors. Herein, a facile molecular precursor route is used to synthesize dual functionalized Fe 2 O 3 two-dimensional nanosheets with phosphate and nitrogen-doped carbon dots (P-Fe 2 O 3 /NCDs) modifications. Taking full use of the excellent characteristics of each component, the optimized P-Fe 2 O 3 /NCDs anode material achieves superior electrochemical features with an outstanding specific capacitance of 453 F g −1 at 1 A g −1 . The cycling stability of P-Fe 2 O 3 /NCDs nanosheets is as high as 91.0 % after 10,000 cycles at 15 A g −1 . Subsequently, phosphate and NCDs modified Co 9 S 8 (P-Co 9 S 8 /NCDs) nanoflowers with convenient ion transport properties are fabricated, which possess a satisfied electrochemical capacity of 569 C g −1 at 1 A g −1 with desirable cycling stability at 15 A g −1 . Impressively, the designed P-Co 9 S 8 /NCDs//P-Fe 2 O 3 /NCDs hybrid supercapacitor can achieve an excellent energy density of 85.1 Wh kg −1 at 937.5 W kg −1 and can retain 93.9 % capacitance efficiency after 20,000 cycles at 10 A g −1 . The superior properties of the dual functionalized electrode materials provide a new choice for constructing advanced hybrid supercapacitors.