Poly(ionic liquid)-derived, N, S-codoped ultramicroporous carbon nanoparticles for supercapacitors

We demonstrate a highly efficient strategy to synthesize N, S-codoped ultramicroporous carbon nanoparticles (N/S-UCNs) via simple polymerization and carbonization of an ionic liquid (IL). By chemical oxidative polymerization of p-phenylenediamine sulfate ([pPD][2HSO(4)]) using ammonium persulfate as an initiator, poly(ionic liquid) (PIL) of p[pPD][2HSO(4)] is obtained, and it acts not only as carbon, nitrogen and sulfur sources, but also as a self-template to generate regular ultramicropores during carbonization. As-prepared N/S-UCNs have nanoscale morphology, uniform ultramicropores (0.50-0.59 nm), high surface area (505-1018 m(2) g(-1)), and high doping content of heteroatoms (N and S). The N/S-UCN carbonized at 600 degrees C (denoted as N/S-UCN600) achieves an optimum balance between specific surface area and high heteroatom doping content, which exhibits good electrochemical performance when it was used as electrode for supercapacitors. N/S-UCN600 electrode shows a high specific capacitance (225 F g(-1) at 2.0 A g(-1)), long-term cycle stability (90.8% retention after 10,000 cycles), and excellent rate capability (160 F g(-1) at 20 A g(-1)) in alkaline electrolyte. The present PIL-derived strategy to fabricate carbon nanoparticles can be easily carried out without any pretreatment, template or activation procedure, which highlights new opportunity to design heteroatom-doped carbons for advanced energy storage applications. (C) 2017 Elsevier B.V. All rights reserved.