Anomalous water molecular gating from atomic-scale graphene capillaries for precise and ultrafast molecular sieving

Abstract Effective ion sieving demands reduction of pore size, which inevitably hinders water flux in hydrophilic membranes, posing a major challenge for precise and ultrafast molecular sieving. Herein, we introduce anomalous liquid gating from nanofiltration membranes full of graphene capillaries at 6 Å with a contact angle of 84°, fabricated from spontaneous restacking of island-on-nanosheet microstructure. We found that ion diffusion driven by osmosis could be suppressed to negligible levels (~ 10− 4 mol m-2 h-1); unexpectedly, ultrafast bulk flow of water (45.4 L m-2 h-1) was still functional with ease, as gated on and off by adjusting hydrostatic pressure differences only in 10− 2 bar. We attribute this to graphene nanoconfinement effect, where confined crystal-like water hinders diffusion under osmosis but facilitates high-speed, diffusion-free water transport in the way analogous to Newton’s cradle-like Grotthus conduction. This strategy establishes liquid-solid-liquid, phase-changing molecular transport, beneficial to resolving long-suffering troubles in conventional realms of molecular sieving.