Core@shell β-FeOOH@polypyrolle derived N, S-codoped Fe3O4@N-doped porous carbon nanococoons for high performance supercapacitors

The combination of carbon and iron oxide has recently attracted increasing research interest in energy conversion and storage. Here, the hybrid nanostructure with N, S-codoped Fe₃O₄ supported/embedded on/in N-doped porous carbon (NS-Fe₃O₄@N-PC) nanococoon was prepared via direct pyrolysis of core@shell β-FeOOH@Polypyrrole (β-FeOOH@PPy) composite. Benefiting from the synergistic effect of high redox activity of NS-Fe₃O₄ and excellent electrical conductivity as well as good mechanical stability of N-PC, the obtained NS-Fe₃O₄@N-PC exhibited an enhanced specific capacitance of 866 F/g at 1 A/g along with excellent rate capability (383 F/g at 10 A/g) and improved cycling stability (78.2% of initial capacitance retained after 5000 cycles test) while applied as electrode materials of supercapacitor. Significantly, the asymmetric supercapacitor devices assembled using NS-Fe₃O₄@N-PC as anodes and commercial carbon nanotubes as cathodes can achieve a large stack energy density of 38.9 Wh/Kg at a stack power density of 700.2 W/Kg along with good stability (only 8.4% decay of initial capacitance after 5000 cycles at 4 A/g). The present work may provide a general approach for fabricating other metal oxide@carbon hybrid nanomaterials for various applications.