Three-dimensional activated carbon nanosheets modified by graphitized carbon dots: One-step alkali pyrolysis preparation and supercapacitor applications

Supercapacitor is a new type of energy storage device, which has the advantages of high-power property and extraordinary life cycle. Herein, three-dimensional activated carbon nanosheets (3-D ACNs) modified with graphitized carbon dots (GCDs) is proposed as a promising electrode material for the supercapacitor. The 3-D ACNs/GCDs are prepared by one-step pyrolysis strategy with the assistance of alkali (KOH) from an organic molecular precursor of Span 20. The crystal structure, morphology, pore structure of the product is investigated by XRD, SEM/TEM and BET techniques, respectively. The capacitive performances of the electrode are studied by CV and CDC techniques. The 3-D ACNs/GCDs product has a well 3-D porous structure and high specific surface area of 1328 m2 g−1. The capacitive performances of the 3-D ACNs/GCDs electrode material are satisfactory, revealing a high specific capacitance (202.9 F g−1 at 1 A g−1) and good rate performance (144.2 F g−1 at 5 A g−1) in three-electrode test system, as well as long cycle stability (93.2% or 87.7% capacitance retention after 2000 or 6000 cycles) in two-electrode symmetric supercapacitor.