(551a) Large-Area Single Layer Graphene Membrane By Crack-Free Transfer for Gas Mixture Separation

Nanoporous single-layer suspended graphene films have been predicted to be the ultimate membranes, capable of providing orders of magnitude higher permeance that that from the state-of-the-art membranes.^1-3 This is mainly because of the ultrashort diffusional path of the molecules across the two-dimensional graphene film. However, the development of such membranes is impeded by two major bottlenecks; (i) incorporation of molecular-size nanopores in otherwise impermeable graphene, (ii) crack- and tear-free transfer of graphene to a porous substrate. Here we report novel approaches that overcome these bottlenecks, leading to formation of 1 mm²-sized single-layer graphene membranes (40000-fold larger than the state-of-the-art single-layer graphene membranes).⁴

The membrane was stable during multiple cycles of heating and cooling, and at least up to moderate transmembrane pressure differences (7 bar). Attractive gas sieving performance (H₂ permeance up to 4.1 x 10^-7 mol m^-2 s^-1 Pa^-1 with H₂/CH₄ selectivities up to 25) were achieved from graphene film with a minuscule porosity of 0.025%. Use of gas mixture feed did not reduce either the H₂ permeance or the H₂/CH₄ separation selectivity. Finally, we report post-synthetic performance tuning of the graphene membrane by ozone-functionalization, improving H₂ permeance (up to 300%) as well as H₂/CH₄ selectivities (up to 150%). Overall, the methods developed here can be instrumental to realize large-scale deployment of the nanoporous two-dimensional membrane.

References

1. Jiang, D.-E., Cooper, V. R. & Dai, S. Porous graphene as the ultimate membrane for gas separation. Nano Lett. 9, (2009).
2. Koenig, S. P., Wang, L., Pellegrino, J. & Bunch, J. S. Selective molecular sieving through porous graphene. Nat. Nanotechnol. 7, 728–732 (2012).
3. Celebi, K. et al. Ultimate permeation across atomically thin porous graphene. Science 344, 289–92 (2014).
4. Agrawal, K. et al., Single-Layer Graphene Membranes by Crack- Free Transfer for Gas Mixture Separation. Nat. Commun. 2018