Hydrogen-bonded organic framework-derived, flower-on-fiber-like, carbon nanofiber electrodes for supercapacitors

Abstract

Hydrogen-bonded organic frameworks (HOFs) are a new type of porous material and have great potential as electrode material precursors because of their high porosity. Here, we report a HOF-derived carbon nanofiber with a unique “flower-on-fiber” morphology prepared by anchoring melamine cyanurate (MCA) on polyacrylonitrile (PAN) nanofibers via electrospinning and post-carbonization. The anchored MCA acts not only as a heteroatom-donor but also as a structure-directing agent. The optimum PAN@MCA carbon nanofiber (c-PAN@MCA_0.25) had a high nitrogen content of 13.5 at% and a specific surface area of 403.1 m² g⁻¹. Furthermore, c-PAN@MCA_0.25 possessed a high specific capacitance of 338.6 F g⁻¹ at a current density of 1 A g⁻¹ in a three-electrode configuration. The outstanding electrochemical performance of c-PAN@MCA_0.25 was confirmed by analyzing ion diffusion and reaction kinetics. In addition, the symmetric supercapacitors based on c-PAN@MCA_0.25 exhibited a superior cycling stability of 95.02% after 10 000 cycles with almost 100% coulombic efficiency. Furthermore, the symmetric device demonstrated an excellent energy density of 11.4 W h kg⁻¹ at a power density of 344 W kg⁻¹, a higher value than that of previously reported electrospun carbon nanofiber-based aqueous supercapacitors. The high performance is due to wrinkled sheet morphology, hierarchical porosity, and high heteroatom doping. This research will pave the way for the development of HOF-based electrode materials.