Addressing the global clean water crisis necessitates membranes capable of both effective ion sieving and high water flux. This study introduces anomalous water molecular gating using nanofiltration membranes comprised of 6 Å graphene capillaries, fabricated via π–π restacking of graphitic microstructures. The membrane effectively sieves ions, reducing osmosis-driven ion diffusion to negligible levels (~10⁻¹⁰⁺ mol m⁻² h⁻¹), while maintaining ultrafast water flux (45.4 L m⁻² h⁻¹) controlled by hydrostatic pressure. This is attributed to graphene nanoconfinement, where crystal-like water facilitates high-speed, diffusion-free transport analogous to Grotthus conduction. This approach establishes a liquid-solid-liquid, phase-changing molecular transport for precise and ultrafast molecular sieving.

Qian Zhang, Bo Gao, Ling Zhang, Xiaopeng Liu, Jixiang Cui, Yijun Cao, Hongbo Zeng, Qun Xu, Xinwei Cui, Lei Jiang