ZIF-8 nanocrystals derived N-doped carbon decorated graphene sheets for symmetric supercapacitors

Sandwich-like ZIF-8 nanocrystal derived N-doped carbon decorated graphene sheets are developed through in-situ growth and followed by a thermal annealing treatment. The sandwich-like N-doped carbon decorated graphene sheets (NCGs) contain graphene substrate and the carbon nanoparticles with 30–50 nm in size. The sandwich-like NCGs generate a large specific surface area of 816.4 m 2  g −1 . With the high surface area and nitrogen doping, the as-fabricated NCGs as electrode materials for supercapacitor exhibit high specific capacitance of 225.0 F g −1  at 0.5 A g −1 , an enhanced rate capability and excellent electrochemical stability with 96.8% retention after 10000 cycles even at 10 A g −1 . The symmetry supercapacitor based on NCGs delivers an energy density of 12.7 Wh kg −1  at a specific power of 447 W kg −1 . When the power density increases to 15126 W kg −1 , the energy density can still keep 6.5 W h kg −1 . Furthermore, the symmetry supercapacitor shows an excellent cycle stability with 96.6% capacitance retention at 2 A g −1 after 10000 cycles.