Helium Isotopes Quantum Sieving through Graphtriyne Membranes

We report accurate quantum calculations of the sieving of Helium atoms by two-dimensional (2D) graphtriyne layers with a new interaction potential. Thermal rate constants and permeances in an ample temperature range are computed and compared for both Helium isotopes. With a pore larger than graphdiyne, the most common member of the gamma-graphyne family, it could be expected that the appearance of quantum effects were more limited. We find, however, a strong quantum behavior that can be attributed to the presence of selective adsorption resonances, with a pronounced effect in the low temperature regime. This effect leads to the appearance of some selectivity at very low temperatures and the possibility for the heavier isotope to cross the membrane more efficiently than the lighter, contrarily to what happened with graphdiyne membranes, where the sieving at low energy is predominantly ruled by quantum tunneling. The use of more approximate methods could be not advisable in these situations and prototypical transition state theory treatments might lead to large errors.

Automated summary

This study reports accurate quantum calculations of Helium atom sieving by two-dimensional graphtriyne layers with a new interaction potential. Despite expectations of limited quantum effects due to larger pore size compared to graphdiyne, strong quantum behavior was observed, attributed to selective adsorption resonances with a pronounced effect in the low temperature regime. This led to selectivity at very low temperatures and more efficient crossing of the membrane by heavier isotopes.