Nitrogen and oxygen co-doped 3D nanoporous duct-like graphene@carbon nano-cage hybrid films for high-performance multi-style supercapacitors

Interconnected 3D graphene foams with a large number of controllable micro-mesoporous structures are promising electrode materials for supercapacitors due to their high electrical conductivity and large effective surface area. Here we successfully obtained a flexible high-quality nitrogen and oxygen co-doped 3D nanoporous duct-like graphene@carbon nano-cage film by chemical vapor deposition using nanoporous copper (NPC) as the substrate and further modifying with HNO3. The bicontinuous mesoporous architecture catalyzed by NPC retains the 2D coherent electronic properties of graphene. Carbon nano-cages grown on the surface of the 3D nanoporous graphene combined with the microporous structure caused by heteroatom-doping greatly increase the effective specific surface area. Moreover, heteroatom-doping and oxygen-containing groups on the surface of graphene can obtain extra redox capacitance and achieve good wettability between the electrode and the electrolyte. The superior structure means that NO-3DG@CNC-based multi-style supercapacitors, such as aqueous-system, ionic-system, and lithium-ion capacitors etc., all show high energy density, high power density and excellent cycling stability.