Nitrogen-Doped Carbon Polyhedra Nanopapers: An Advanced Binder-Free Electrode for High-Performance Supercapacitors

Metal–organic framework (MOF)-derived nitrogen-doped porous carbon as electrode material for supercapacitors has recently drawn much attention. However, the development of flexible electrodes composed of MOF-derived carbon is still a great challenge. Herein, nitrogen-doped porous carbon polyhedra (NC) derived from zeolitic imidazolate framework-8 (ZIF8) are assembled into flexible nanopapers assisted with reduced graphene oxide (rGO). The resultant NC/rGO nanopaper shows a hierarchical structure of NC nanoparticle-imbedded rGO framework. A uniform dispersion of NC nanoparticles is achieved due to the rGO framework, and meanwhile, the uniform decoration of NC nanoparticles on rGO nanosheets prevents easy restacking of rGO. A conductive rGO framework further accelerates the electron/ion transportation inside the NC/rGO nanopaper. Furthermore, excellent mechanical performance of rGO framework endows high flexibility to the NC/rGO nanopaper. As a result, the NC/rGO nanopaper as a binder-free electrode delivers high specific capacitance of 280 F g^–1 at 1 A g^–1, high capacitance retention after 5000 cycles, and high energy density of 19.45 W h kg^–1.