From Molecules to Materials: Computational Design of N-Containing Porous Aromatic Frameworks for CO_2 Capture

摘要

Porous aromatic frameworks (PAFs) are novel materials with diamond topology. With the aim of enhancing their CO_2 capture and storage capacity and investigating the effect of nitrogen and/or -COOH decorations on CO_2 adsorption in PAFs, a series of N-containing PAFs were designed based on ab initio results. The interaction energies (Eint) between CO_2 and each six-membered ring were calculated at the B2PLYP-D2/def2-TZVPP level, then the six-membered rings with high CO_2-binding affinity were selected and used in the PAFs. To explore the performance of the designed PAFs, the CO_2 uptake, selectivity of CO_2 over CH_4, H_2, and N_2, and the E_(int) value of CO_2 in PAFs were investigated by using grand canonical Monte Carlo (GCMC) simulations and ab initio calculations. This work shows that pyridine with one nitrogen atom can provide a strong physisorption site for CO_2, whereas more nitrogen atoms in heterocycles will reduce the interaction, especially at relatively low pressure. PAFs with -COOH groups show high CO_2 capacity. Our work provides an efficient way to understand the adsorption mechanism and a supplemental approach to experimental work.