A general strategy to synthesize high-level N-doped porous carbons via Schiff-base chemistry for supercapacitors

Recently, the synthesis of porous carbon-based materials, especially those with unique geometry, narrow pore size distribution, large surface area and high nitrogen content, has been highly attractive for widespread applications, but remains a great challenge. Herein, we demonstrate a novel strategy for highly efficient synthesis of high-level N-doped microporous carbon spheres (N-MCSs) based on a very simple Schiff-base reaction of 3,3-diaminobenzidine and p-phthalaldehyde in ethanol solvent without any catalyst or tedious procedure, followed by a common one-step carbonization-activation process. The N-MCSs exhibit a spherical morphology, regular micropores, high surface areas and high nitrogen contents (up to 8.71 at%). N-MCSs used as supercapacitor electrodes deliver high gravimetric capacitance, good rate capability and cycling stability. More importantly, the synthetic approach can be extended to other Schiff-base systems such as p-phthalaldehyde and p-phenylenediamine or ethylenediamine to fabricate porous carbon-based materials with high nitrogen species, tunable morphology and pore structure. The general strategy presented in this study opens up a new window for heteroatom doping, geometry and structure control, and highlights the great potential of well-developed carbon-based materials for extensive applications.