Atomically thin graphene with a high-density of precise subnanometer pores represents the ideal membrane for ionic and molecular separations. However, a single large-nanopore can severely compromise membrane performance and differential etching between pre-existing defects/grain boundaries in graphene and pristine regions presents fundamental limitations. Here, we show for the first time that size-selective interfacial polymerization after high-density nanopore formation in graphene not only seals larger defects (>0.5 nm) and macroscopic tears but also successfully preserves the smaller subnanometer pores. Low-temperature growth followed by mild UV/ozone oxidation allows for facile and scalable formation of highdensity (4−5.5 × 10 12 cm −2 ) useful subnanometer pores in the graphene lattice. We demonstrate scalable synthesis of fully functional centimeter-scale nanoporous atomically thin membranes (NATMs) with water (∼0.28 nm) permeance ∼23× higher than commercially available membranes and excellent rejection to salt ions (∼0.66 nm, >97% rejection) as well as small organic molecules (∼0.7−1.5 nm, ∼100% rejection) under forward osmosis.

We report on a roll-to-roll manufacturing compatible isopropanol-assisted-hot-lamination process for facile fabrication of large-area nanoporous atomically thin graphene membranes (NATMs) for dialysis and molecular separations.

Selective subatomic separations Membranes are thin materials used to selectively separate gases or liquids and are used on a range of scales from benchtop experiments to industrial processes. Challenges arise in separating materials with very similar sizes or chemical properties, particularly at the smallest scales. Kidambi et al . review advances in using atomically thin two-dimensional materials such as graphene or hexagonal boron nitride for the separation of subatomic species, including electrons, hydrogen isotopes, and gases. The authors explore the scope to scale up the sizes of these membranes and their potential use in applications relating to energy, microscopy, and electronics. —MSL