Efficient CO2 capture and separation in TpPa COFs: Synergies from functional groups and metal Li.

The CO 2 capture and separation performances are enhanced by improving structural polarity and providing CO 2 adsorption sites through introduced functional groups and Li. There is a synergistic effect between these modifications in improving performances. Notably, TpPa-SO 3 Li demonstrates the highest CO 2 capture capacity of 136.11 cm3 cm−3, along with the CO 2 over N 2 /CH 4 selectivity of 264.22/164.38, respectively. [Display omitted] • CO 2 capture and separation performances are evaluated in TpPa COFs modified by functional group and Li using GCMC and DFT. • There is a synergistic effect between functional groups and metal Li in enhancing the selective CO 2 capture performance. • TpPa-SO 3 Li exhibits the best CO 2 capture capacity of 136.11 cm3 cm−3 with the CO 2 over N 2 /CH 4 selectivity of 264.22/164.38, respectively. • Improved structural polarity and additional metal adsorption sites are the main reasons for optimized performances. Covalent organic frameworks (COFs) have emerged as promising materials for CO 2 capture and separation owing to their exceptional structural stability. Herein, grand canonical Monte Carlo simulation (GCMC) and density functional theory (DFT) were used to first screen the most favorable functional group in the COFs consisting of 1,3,5-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa) functionalized with –OH, –COOH, and –SO 3 H, respectively (TpPa-X). Subsequently, the H atoms of –SO 3 H, the best functional group, were replaced by Li atoms to form –SO 3 Li, revealing the synergies of functional group –SO 3 H and Li modification on selective CO 2 capture. TpPa-OLi/COOLi were also constructed to confirmed the universality of this synergistic effect. The introduction of functional groups enhanced the CO 2 capture and separation performances by creating a more suitable pore environment. The Li introduction increased the structural polarity and provided strong adsorption sites, further improving the selective CO 2 capture performance. Notably, TpPa-SO 3 Li exhibited a remarkable CO 2 adsorption capacity of 136.11 cm3 cm−3 with the CO 2 over N 2 /CH 4 selectivity of 264.22/164.38, respectively, at 298 K and 1.0 bar. Structural stabilities, pore characteristics, gas adsorption distribution, isothermal adsorption heat, and interactions were adopted to reveal the synergistic effect between functional groups and Li in enhancing CO 2 capture and separation. [ABSTRACT FROM AUTHOR]