Nanoporous membranes based on two dimensional materials are predicted to provide highly selective gas transport in combination with extreme permeability. Here we investigate membranes made from multilayer graphdiyne, a graphene-like crystal with a larger unit cell. Despite being nearly a hundred of nanometers thick, the membranes allow fast, Knudsen-type permeation of light gases such as helium and hydrogen whereas heavy noble gases like xenon exhibit strongly suppressed flows. Using isotope and cryogenic temperature measurements, the seemingly conflicting characteristics are explained by a high density of straight-through holes (direct porosity of ~0.1%), in which heavy atoms are adsorbed on the walls, partially blocking Knudsen flows. Our work offers important insights into intricate transport mechanisms playing a role at nanoscale.

中文翻译：

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通过基于石墨二炔的纳米多孔膜的气体渗透

预计基于二维材料的纳米多孔膜可提供高选择性的气体传输以及极高的渗透性。在这里，我们研究了由多层石墨二炔制成的膜，这是一种具有较大晶胞的类石墨烯晶体。尽管有近一百纳米厚，但这些膜允许快速、克努森型的轻气体（如氦气和氢气）渗透，而重惰性气体（如氙气）则表现出强烈的抑制流动。使用同位素和低温温度测量，看似矛盾的特性可以通过高密度的直通孔（直接孔隙率约为 0.1%）来解释，其中重原子吸附在壁上，部分阻塞了 Knudsen 流。我们的工作为在纳米尺度上发挥作用的复杂传输机制提供了重要的见解。