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 Fe2O3 two-dimensional nanosheets with phosphate and nitrogen -doped carbon dots (P-Fe2O3/NCDs) modifications. Taking full use of the excellent characteristics of each component, the optimized P-Fe2O3/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-Fe2O3/NCDs nanosheets is as high as 91.0 % after 10,000 cycles at 15 A g(-1). Subsequently, phosphate and NCDs modified Co9S8 (P-Co9S8/ NCDs) nanoflowers with convenient ion transport properties are fabricated, which possess a satisfied electro-chemical capacity of 569 C g(-1) at 1 A g(-1) with desirable cycling stability at 15 A g(-1). Impressively, the designed P-Co9S8/NCDs//P-Fe2O3/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.