Nitrogen-doped porous carbon nanosheets derived from poly(ionic liquid)s: Hierarchical pore structures for efficient CO₂ capture and dye removal

Poly(ionic liquid) has recently served as an important precursor for nitrogen-doped functional porous carbons. It was applied here in a facile one-pot approach to synthesize nitrogen-doped porous carbon nanosheets (NPCNSs) using C₃N₄ nanosheets as sacrificial templates. C₃N₄ nanosheets are found to improve the carbonization yield and nitrogen content of NPCNSs and additionally facilitate the formation of a unique pore structure. Without post-treatments or activation steps, the as-synthesized NPCNS readily reaches a specific surface area above 1100 m² g^-1 with hierarchical micro-/meso-/macropore structures while keeping a high nitrogen content (17.4 wt%). More significantly, the NPCNS is able to deliver not only a high CO₂ adsorption capacity with outstanding reversibility, but also an unprecedented capacity in methylene blue uptake by 962.1 mg g^-1, which is among the few highest ever reported for wastewater, with excellent reusability.