Kinetics control over the Schiff base formation reaction for fabrication of hierarchical porous carbon materials with tunable morphology for high-performance supercapacitors.

Schiff base formation reaction is highly dynamic, and the microstructure of Schiff base polymers is greatly affected by reaction kinetics. Herein, a series of Schiff base cross-linked polymers (SPs) with different morphologies are synthesized through adjusting the species and amount of catalysts. Nitrogen/oxygen co-doped hierarchical porous carbon nanoparticles (HPCNs), with tunable morphology, specific surface area (SSA) and porosity, are obtained after one-step carbonization. The optimal sample (HPCN-3) possesses a coral reef-like microstructure, high SSA up to 1003 m2g-1, and a hierarchical porous structure, exhibiting a remarkable specific capacitance of 359.5 F g-1(at 0.5 A g-1), outstanding rate capability and cycle stability in a 1 M H2SO4electrolyte. Additionally, the normalized electric double layer capacitance (EDLC) and faradaic capacitance of HPCN-3 are 0.239 F m-2and 10.24 F g-1respectively, certifying its superior electrochemical performance deriving from coral reef-like structure, high external surface area and efficient utilization of heteroatoms. The semi-solid-state symmetrical supercapacitor based on HPCN-3 delivers a capacitance of 55 F g-1at 0.5 A g-1, good cycle stability of 86.7% after 5000 GCD cycles at 10 A g-1, and the energy density ranges from 7.64 to 4.86 Wh kg-1.