Abstract
Nature Communications 2022, 13, 6709
Differences in water and vapor transport through angstrom-scale pores in atomically thin membranes
Cheng P, Fornasiero F, Jue ML, Ko W, Li AP, Idrobo JC, Boutilier MS, Kidambi PR
The transport of water through nanoscale capillaries/pores plays a prominent role in biology, ionic/molecular separations, water treatment and protective applications. However, the mechanisms of water and vapor transport through nanoscale confinements remain to be fully understood. Angstrom-scale pores (~2.8–6.6 Å) introduced into the atomically thin graphene lattice represent ideal model systems to probe water transport at the molecular-length scale with short pores (aspect ratio ~1–1.9) i.e., pore diameters approach the pore length (~3.4 Å) at the theoretical limit of material thickness. Here, we report on orders of magnitude differences (~80×) between transport of water vapor (~44.2–52.4?g?m?2 day?1 Pa?1) and liquid water (0.6–2?g?m?2 day?1 Pa?1) through nanopores (~2.8–6.6 Å in diameter) in monolayer graphene and rationalize this difference via a flow resistance model in which liquid water permeation occurs near the continuum regime whereas water vapor transport occurs in the free molecular flow regime. We demonstrate centimeter-scale atomically thin graphene membranes with up to an order of magnitude higher water vapor transport rate (~5.4–6.1?×?104?g?m?2 day?1) than most commercially available ultra-breathable protective materials while effectively blocking even sub-nanometer (>0.66?nm) model ions/molecules.