Title: Gas permeation through graphdiyne-based nanoporous membranes
Authors: Zhihua Zhou, Yongtao Tan, Qian Yang, Achintya Bera, Zecheng Xiong, Mehmet Yagmurcukardes, Minsoo Kim, Yichao Zou, Guanghua Wang, Artem Mishchenko, Ivan Timokhin, Canbin Wang, Hao Wang, Chongyang Yang, Yizhen Lu, Radha Boya, Honggang Liao, Sarah Haigh, Huibiao Liu, Francois M. Peeters, Yuliang Li*, Andre K. Geim* & Sheng Hu*
Abstract: Nanoporous membranes based on two dimensional materials are predicted to provide highly selective gas transport in combination with extreme permeance. 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.