Gas permeation through graphdiyne-based nanoporous membranes

TL;DR

This study investigates multilayer graphdiyne membranes, revealing their high permeability for light gases and suppressed flow for heavy gases due to pore structure and adsorption effects, providing insights into nanoscale transport mechanisms.

Contribution

It demonstrates the gas permeation properties of multilayer graphdiyne membranes and explains the mechanisms behind selective gas transport at the nanoscale.

Findings

Fast permeation of light gases like helium and hydrogen.

Suppressed flow of heavy noble gases such as xenon.

High density of straight-through pores influences gas transport.

Abstract

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.