Solvent-free, one-pot synthesis of nitrogen-tailored alkali-activated microporous carbons with an efficient CO₂ adsorption

In the present study, a series of alkali-activated carbon materials (TOKs) were prepared by a single-pot polymerization-carbonization-activation method using KOH as a dynamic molecular porogen. The fabricated materials possess tunable porous network with high specific surface area (up to 2847 m²/g), large micropore volume (1.369 cm³/g), and high population of micropores in sub-nanometer range. At 1 bar and 273 K, activated carbons TOK-800 and TOK-900 adsorbed 6.57 mmol/g of CO₂ and 6.85 mmol/g of CO₂, attributed to well-defined micropores ∼0.73 nm with large micropore volume. At low pressure (<0.2 bar), the adsorption capacity ∼2.81 mmol/g of CO₂ and isosteric heat of adsorption ∼37.8 kJ/mol is maximum for the material possessing highest basic nitrogen-content (TOK-700), thereby suggesting a crucial role of basic nitrogen-groups in anchoring acidic CO₂ molecules. Moreover, present work demonstrates an insight mechanism for CO₂ adsorption by micropore filling and illustrate the high adsorption potential of micropores with the pore size less than 0.73 nm. Consequently, as-prepared activated carbons are proclaimed as efficient contenders for CO₂ adsorption, an effort devoted for a green sustainable environment.