Ultrahigh CO2 capture and separation in 3D Cage-COFs: Synergistic effect from Li, topology, and pore size

• Published in: Separation and purification technology 2025-04, Vol.356, p.129897, Article 129897
• Main Authors: Zhang, Huili, Wang, Zhaojie, Liu, Sen, Li, Wenchuan, Wei, Shuxian, Wang, Maohuai, Zhang, Ling, Lyu, Weifeng, Liu, Siyuan, Lu, Xiaoqing
• Format: Article
• Language: English
• Subjects: CO2 capture and separation; COF; Synergistic effect
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.129897

The CO2 capture and separation performances are enhanced by optimizing pore environment through metal Li introduction, topology regulation, and pore size adjustment. There is a synergistic effect between these modifications in improving performances. Notably, COF-3fold-OLi2 exhibits the highest CO2 capture capacity of 236.10 cm3 cm−3 and CO2 over N2/CH4 selectivity of 205.87/94.37 at 298 K and 1.0 bar. [Display omitted] •CO2 capture and separation performances are evaluated in 3D Cage-COFs modified by Li, topology, and pore size using GCMC and DFT.•There is a synergistic effect between Li, topology, and pore size modification in enhancing the selective CO2 capture performance.•COF-3fold-OLi2 exhibits the best CO2 capture capacity of 236.10 cm3 cm−3 with the CO2 over N2/CH4 selectivity of 205.87/94.37 at 298 K and 1.0 bar.•Optimized adsorption pore environment is the main reason for enhanced performance.•Grasp the “degree” of modification to maximize synergistic effect. The urgency of mitigating excessive CO2 emissions has promoted the development of CO2 adsorbents. Three-dimensional Cage-Covalent organic frameworks (3D Cage-COFs) are excellent candidates due to their outstanding pore features and diversified adjustability. Herein, CO2 capture and separation performances in 3D Cage-COFs modified by metal Li, topology, and pore size were investigated by Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT). It is shown that the introduction of Li enhanced structural polarity and provided efficient CO2 adsorption sites. Topological structure regulation optimized the space utilization and adsorption site distribution. Moreover, pore size adjustment mitigated adsorption site blockages caused by Li and topological regulation. With the synergistic effect of the above modifications, COF-3fold-OLi2 exhibited the highest CO2 capture capacity of 236.10 cm3 cm−3 with a selectivity of 205.87/94.37 over N2/CH4 (v: v = 50: 50) at 298 K and 1.0 bar. The synergistic effect of metal Li, topology, and pore size on improving CO2 capture and separation performances was illustrated through structural stability, pore characteristics, gas distribution, adsorption configuration, radial distribution function, isothermal adsorption heat, and interactions. These insights are essential for developing adsorbent materials for CO2 capture and separation.