Comparative study of activation methods to design nitrogen-doped ultra-microporous carbons as efficient contenders for CO₂ capture

Microporous carbon materials are envisaged as efficient contenders for mitigating CO₂ levels by virtue of their favorable surface chemistry, high specific surface area, tunable pore structures, moderate heat of adsorption, and facile regeneration. This study presents a solvent-free one-step polymerization and activation method for designing a series of nitrogen-enriched carbons to delineate the role played by nitrogen moieties and ultra-micropores on CO₂ capture. Two activating agents were used at high temperature to fabricate microporous carbons with tunable pore structure and variable nitrogen content. The optimized material, MCKC-3, possesses high surface area (2060 m²/g) comprising of ultramicropores (<0.7 nm) and high nitrogen content (2.3 wt%). This material exhibit an outstanding CO₂ uptake performance of 354 mg/g (8.03 mmol/g) at 273 K and 1 bar, comparable to the highest adsorption reported so far for carbon-based materials. In conclusion presence of both the ultra-micropores and nitrogen functionalities contribute a major role in CO₂ adsorption, the former being predominant.