On the CO 2 Harvesting from N 2 Using Grazyne Membranes.

The separation of carbon dioxide (CO 2 ) from nitrogen (N 2 ) is at the core of any global warming remediation technology aimed at reducing the CO 2 content in the atmosphere. Chemical membranes designed to differentially permeate both molecules have become quite appealing due to their simple use, although many membrane-based separations stand out as a promising solution for CO 2 separation. These are environmentally friendly, with high active surface areas, compact design, easy to maintain and cost-effective, although the field is still growing due to the difficulties in the CO 2 /N 2 separation. The present study poses grazynes, two-dimensional C-based materials with sp and sp 2 C atoms, aligned along stripes, as suited membranes for the CO 2 /N 2 separation. The combination of density functional theory (DFT) and molecular dynamics (MD) simulations allow tackling the energetics, kinetics, and dynamics of the membrane effectiveness of grazynes with engineered pores for such a separation in a holistic fashion. The explored grazynes are capable of physisorbing CO 2 and N 2 , thus avoiding material poisoning by molecular decoration, while the diffusion of CO 2 through the pores is found to be rapid, yet easier than that of N 2 , in the rate order of the s -1 in the 100-500 K temperature range. In particular, low-temperature CO 2 separation even for CO 2 contents below 0.5 % are found for [1],[2]{2}-grazyne when controlling the membrane exposure contact to the gas mixture, paving the way for exploring and using grazynes for air CO 2 remediation.