N-doped activated carbon for enhanced CO2 sorption through self-activation

Abstract

In this research, nitrogen-doped activated carbons (NACs) featuring a high specific surface area (3396 m²/g) and a certain amount of nitrogen doping (0.79–1.69%) were prepared by a combination of chemical activation and self-activation methods, and their CO₂ adsorption characteristics were comprehensively assessed. The experimental results showed that nitrogen doping not only significantly enhanced the specific surface area of the materials, but also significantly enhanced the CO₂ adsorption. The CO₂ adsorption capacity of the optimal sample, CMAC-0.5–3-700, reached 4.11 mmol/g and 2.32 mmol/g at 0 °C and 25 °C, respectively. In addition, the selectivity of NACs for CO₂/N₂ was significantly improved, with a selectivity factor of up to 50.16, and the competitive adsorption experiments also demonstrated that NACs could still effectively adsorb CO₂ under the condition of CO₂/N₂ = 15/85. Density-functional theory (DFT) calculations further revealed the interaction mechanism between NACs and CO₂ molecules, the enhanced CO₂ selectivity is attributed to electrostatic and π-electron interactions between nitrogen atoms and CO₂. The findings indicate the significant potential of nitrogen-doped activated carbons (NACs) with high specific surface area and substantial nitrogen doping for post-combustion CO₂ capture.