(401ak) Gas Separation from Intrinsic Defects of Single Layer Graphene

Block-copolymer derived nanoporous carbon membranes for high throughput gas separation

Atom thick graphene membrane, the thinnest possible molecular barrier, is an ideal membrane for the gas separation.^1–3 However, route to fabricate a large-area, crack-free graphene membrane has not been demonstrated. Cracks and tears eclipses the intrinsic separation performance from nanoporous graphene, therefore till-date, gas mixture separation through single-layer graphene film has not been reported. Herein, by developing, a novel transfer technique, we report gas separation from chemical vapor deposition (CVD) synthesized atom thick graphene membrane from an area as large as 1 mm². No cracks or tears were observed in the graphene membrane by SEM. To the best of our knowledge, before this work, gas separation studies from single-layer graphene membranes have been limited to the length scale of a few micron.

The gas permeation experiments with four gases (H₂, He, CH₄, and CO₂) at variable temperatures (25-200 °C) were conducted to study the transport properties of the intrinsic defects of atom-thick graphene film. Resulting permeance of CH₄ and CO₂ were 6 and 16 GPU, respectivelyat 200 °C. Moreover, He/CH₄ ideal gas selectivity was as high as 29 with He permeance of 183 GPU at 200 °C. Interestingly, we also observed H₂/CO₂ selectivity (8.8) with H₂ permeance of 137 GPUat 200 °C, indicating that average size of nanopores in graphene was somewhat smaller than that of the kinetic diameter of CO₂. The permeance increased with temperature, indicating molecular transport was in the activated transport regime. This high gas selectivity observed from a 1 mm² large graphene membrane is first proof-of-principle report on gas separation from large-scale single-layer graphene film.

References:

(1) Koenig, S. P.; Wang, L.; Pellegrino, J.; Bunch, J. S. Selective Molecular Sieving through Porous Graphene. Nat Nano 2012, 7 (11), 728–732.

(2) Celebi, K.; Buchheim, J.; Wyss, R. M.; Droudian, A.; Gasser, P.; Shorubalko, I.; Kye, J.-I.; Lee, C.; Park, H. G. Ultimate Permeation across Atomically Thin Porous Graphene. Science 2014, 344 (6181), 289–292.

(3) O’Hern, S. C.; Stewart, C. a; Boutilier, M. S. H.; Idrobo, J.-C.; Bhaviripudi, S.; Das, S. K.; Kong, J.; Laoui, T.; Atieh, M.; Karnik, R. Selective Molecular Transport through Intrinsic Defects in a Single Layer of CVD Graphene. ACS Nano 2012, 6 (11), 10130–10138.