Morphology transition of FeOOH induced by N-doped graphene for excellent pseudocapacitive energy storage

The iron-based materials have been extensively investigated for supercapacitors due to their ample redox chemistry, low toxicity and large reserves. However, they were restricted in practical application because of poor electrical conductivity and unsatisfied cycling stability. In this work, an urchin-like FeOOH was obtained induced by N-doped reduced graphene oxide (NrGO) support via fast electrodeposition. The as-obtained NrGO/FeOOH/ NrGO (NFN) electrode exhibits an impressive specific capacitance of 1483 F g−1 at 1 A g−1 and exhibited a great rate capability at a high current density. The symmetric supercapacitor (SSC) was assembled by using NFN hybrid material as a positive and negative electrode in 2 M KOH solution, respectively. The as-assembled NFN//NFN device achieves a high energy density of 86.3 Wh kg−1 at a high power density of 1600.9 W kg−1 and maintains 95.1% capacitance retention after 15,000 test cycles, indicating ultralong cycling life. The morphology characterization, density functional theory (DFT) and electrochemical tests reveal that the construction of urchin-like FeOOH sandwiched in double-layer N-doped graphene can effectively and synergistically enhance the electrochemical performance, which may inspire the fabrication of electrode materials in supercapacitors.