Simply synthesized N-doped carbon supporting Fe3O4 nanocomposite for high performance supercapacitor

Metal oxides have attracted a lot of attention in energy conversion and storage due to their high capacitance. In this work, the polydopamine nanospheres (PDA) was used to adsorb iron ions in solution, and then the mixture was calcined at high temperature to form nitrogen doped (N-doped) carbon (NCSs) supporting Fe3O4 (NCSs@Fe3O4). The as-prepared nanocomposite carbonized at 750 °C with large specific surface area of 349.5 m2 g−1 and large number of pores distributed at 2–10 nm, exhibiting excellent electrochemical performance. Its specific capacitance can reach 206 F g−1 at the current density of 1 A g−1, and still keep 95% of the initial capacity after 5000 cycles. The NCSs@Fe3O4//NCSs asymmetric supercapacitor was constructed using NCSs@Fe3O4 as cathode electrode material and NCSs as anode electrode material. The results of a series of tests indicated that the asymmetric supercapacitor has excellent capacitive performance, suggesting that NCSs@Fe3O4 composite is a favorable candidate for supercapacitor. •The NCSs@Fe3O4 nanocomposites was synthesized by adsorption and pyrolysis methods.•The NCSs@Fe3O4 electrode exhibits high specific capacitance and good rate capability.•The electrode material has 95% initial capacitance retention after 5000 cycles.•The NCSs@Fe3O4//NCSs asymmetric supercapacitor displays high energy density and power density.