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

Abstract

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.