Nitrogen-doped hierarchically porous carbon nanosheets derived from polymer/graphene oxide hydrogels for high-performance supercapacitors.

Design and fabrication of the nitrogen-doped carbon materials with hierarchically porous structure is crucial for improving the electrochemical performance of supercapacitors. In this study, facile fabrication of the nitrogen-doped hierarchical carbon nanosheets (i.e. HGPC-A) is demonstrated via one-step carbonization and activation strategy using the polyvinyl alcohol/polyaniline (PVA/PANI) hydrogels as precursors in the presence of graphene oxide (GO). Benefiting from the covalent bonding assembly between GO and PVA/PANI polymers, the as-obtained HGPC-A with the hierarchical and interconnected nanosheet structure exhibits the high specific surface area and abundant macro-/meso-/micropore channels. It is also found that the introduction of the graphene has a significant effect on increasing the pyridinic-N ratio and enhancing the structural stability of HGPC-A in comparison to the pristine PVA/PANI hydrogel-derived carbon materials (HPC-A). Remarkably, these fascinating structure features of the HGPC-A enable the high charge storage performance as the electrode for supercapacitor, highlighted by a high specific capacitance of 311 F g-1 with superior rate capability of 64.3% when the current density increased from 0.5 A g-1 to 20 A g-1. Moreover, the integrated symmetric supercapacitor using the HGPC-A electrodes displays superb cycling durability of 88.5% over 10,000 cycles and high charge storage capacity of 7.0 Wh kg-1.