Fabrication of nitrogen-doped porous carbons for highly efficient CO2 capture: rational choice of a polymer precursor

Because of the high stability, tailorable surface properties, and plentiful porosity, nitrogen-doped porous carbons (NPCs) are of great interest for CO2 capture. Carbonization of nitrogen-containing polymers is regularly utilized for the fabrication of NPCs, but such a method is obstructed by the high cost of some polymer precursors. Here we demonstrate the preparation of NPCs via the rational choice of a low-priced, nitrogen-rich polymer NUT-1 (NUT represents Nanjing Tech University) as the precursor, for the first time. The polymer NUT-1 was synthesized by the polymerization of two easily available monomers under mild conditions without the use of any catalysts. Carbonization at temperatures ranging from 500 to 800 degrees C leads to the generation of a series of NPCs possessing various porosity and nitrogen contents. The adsorption performance of NPCs is dependent on their pore structure and nitrogendoped CO2-philic sites, while the sample with the largest surface area does not exhibit the highest adsorption amount of CO2. In the case of the material prepared at 600 degrees C (NPC-1-600), the CO2 adsorption amount can reach 7.5 mmol g(-1) at 273 K and 1 bar, which is much higher than that of some benchmark materials, including 13X zeolite (4.1 mmol g(-1)) and activated carbon (2.8 mmol g(-1)), and most if not all reported carbon-based adsorbents. We also demonstrate that KOH plays an important role in the formation of abundant porosity. The reference material NPC-1-600r prepared in the absence of KOH can only adsorb 3.2 mmol CO2 g(-1) at 273 K and 1 bar, which is obviously lower than its counterpart NPC-1-600 (7.5 mmol g(-1)). Our materials may offer to be promising candidates for carbon capture from gas mixtures including natural gas and flue gas.