From molecules to materials: computational design of N-containing porous aromatic frameworks for CO2 capture

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 (E(int)) 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.