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.
@article{arxiv.2207.00731,
title = {Gas permeation through graphdiyne-based nanoporous membranes},
author = {Zhihua Zhou and Yongtao Tan and Qian Yang and Achintya Bera and Zecheng Xiong and Mehmet Yagmurcukardes and Minsoo Kim and Yichao Zou and Guanghua Wang and Artem Mishchenko and Ivan Timokhin and Canbin Wang and Hao Wang and Chongyang Yang and Yizhen Lu and Radha Boya and Honggang Liao and Sarah Haigh and Huibiao Liu and Francois M. Peeters and Yuliang Li and Andre K. Geim and Sheng Hu},
journal= {arXiv preprint arXiv:2207.00731},
year = {2022}
}