Hierarchically Porous Heteroatom-co-Doped Carbons for Enhanced Carbon Dioxide Capture

The efficiency of carbon dioxide (CO₂) adsorption in carbonaceous materials is primarily influenced by their microporosity and thermodynamic affinity for CO₂. However, achieving optimal heteroatom doping and precise micropore engineering through advanced activation techniques remains a significant challenge. We introduce a solvent-free one-pot method using polythiophene, melamine, and KOH to prepare highly microporous, heteroatom-co-doped carbons (NSC). This approach leverages sulfur from polythiophene, nitrogen from melamine, and the activation agent KOH to enhance CO₂ capture performance. Our results demonstrate that the optimized sample, NSC-800, achieves a CO₂ adsorption capacity of 280.5 mg g⁻¹ at 273 K and 1 bar, attributed to its high nitrogen (6.5 at.%) and sulfur (3.4 at.%) contents, a specific surface area of 2888 m² g⁻¹, and a micropore volume of 1.685 cm³ g⁻¹. The moderate isosteric heat of adsorption (27.7 kJ mol⁻¹) indicates a primarily physisorption-driven mechanism, as confirmed by close alignment with the pseudo-first-order polynomial model (R² > 0.99) across temperatures of 303–323 K. This study reveals that NSC-800 also displays efficient regeneration after ten cycles of CO₂ adsorption–desorption under flue gas conditions (15% CO₂ and 85% N₂ at 313 K), highlighting its potential as a regenerable, energy-efficient adsorbent for practical CO₂ capture applications.