Heteroatom-doped porous carbons exhibit superior CO2 capture and CO2/N2 selectivity: Understanding the contribution of functional groups and pore structure

Abstract The heteroatom-doped porous carbon is an effective strategy to improve the CO2 uptake. However, there are obvious contradictory conclusions in the previous reports regarding the influences of nitrogen groups and pore sizes. Besides this, previous researches about CO2 capture and CO2/N2 selectivity on nitrogen-doped carbon materials often ignore the effect of oxygen-containing functional groups. Herein, we successfully synthesized rich oxygen and nitrogen doped carbon materials by hydrothermal treatment using tobacco stem and ethylenediamine, respectively. The obtained porous carbons exhibit high surface area (906-2940 m2 g-1). From the experimental results, at 1 bar, NC600 exhibits the superior CO2 adsorption of 4.33 mmol g-1 and 6.54 mmol g-1 at 25 ℃ and 0 ℃, respectively. Based on GCMC simulation, we can roughly estimate that the contribution of pore structure and functional groups is 62% and 38%, respectively. Nitrogen and oxygen-doped porous carbons exerts a greater influence on the CO2/N2 selectivity because of the electrostatic interactions enhancement between carbon surface and CO2 molecules. The study is expected to better understand the role of functional groups and pore structure on CO2 capture and CO2/N2 selectivity.