N-doping porous carbon with rich narrow micropores for highly efficient CO2 selective adsorption: Insight from experimental and theoretical study

Abstract

Developing adsorbent with high CO2 capacity and selectivity is of great importance to deal with industrial exhaust emissions and global warming. Herein, we prepared a series porous carbon with rich narrow micropores and abundant nitrogen content through a facile one-step synthesis method, which enable remarkable CO2 uptake (5.74 mmol/g at 25 °C and 1.0 bar) and superior CO2/N2 selectivity (322–66). Such capture performance is much higher than that of other reported carbon adsorbents, and is directly related to the synergistic effect of narrow micropores and surface nitrogen active sites. As demonstrated by a set of systematic theoretical calculations including giant canonical Monte Carlo (GCMC) and density functional theory (DFT) calculations, the narrow micropore favors the diffusion of CO2 molecules and provides large interior for interaction between active sites and CO2 molecules, thus enhancing the CO2 adsorption. Moreover, the as-doped nitrogen active sites show much higher binding energy to CO2 than N2. This strong affinity between the surface and CO2 provides a good explanation for the high selectivity obtained. These results will pave a clearer way for the design and synthesis of carbon materials with high CO2 adsorption performance.