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

Authors: 
Agrawal, K. V., University of Minnesota
Huang, S., École Polytechnique Fédérale de Lausanne (EPFL)
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.