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

Abstract

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 °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 nitrogen-doped “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 °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.