(387h) Single-Layer Graphene Membranes with a Record Performance in Hydrogen Purification and Carbon Capture

Authors: 
Huang, S., École Polytechnique Fédérale de Lausanne (EPFL)
Zhao, J., Nanjing Tech University
Agrawal, K. V., University of Minnesota
With a rising need to cut down the energy usage, the membrane-based separation is highlighted as an energy-efficient process. Single-layer graphene-based membranes have been regarded as the ultimate gas separation membranes, capable of yielding ultrahigh gas permeance and an attractive molecular selectivity, attributing to their atomic thicknesses.1 However, despite their promise, the attractive performance of atom-thick graphene membranes in the size-selective separation of gas mixtures has not been realized. The development of these membranes face two major bottlenecks: 1) crack-free fabrication of large-area membranes; 2) incorporation of moderate to high-density of size-selective nanopores in the impermeable graphene lattice while avoiding non-selective pores.

Herein, we reported several novel approaches to achieve record-high gas separation performance from single layer graphene-based membrane. A novel nanoporous-carbon-assisted graphene transfer technique was developed, enabling transfer of relatively large area single-layer graphene onto a macroporous support, hosting pores with pore-opening of 5 µm, without inducing cracks or tears.2 By decoupled pore-nucleation and pore-expansion strategy, a high pore-density (2.1 × 1012 pores/cm2) with a tight pore-size distribution was incorporated in single-layer graphene film, resulting in a record gas mixture separation performance (H2 permeance of 1340 to 6045 gas permeation units (GPU); H2/CH4 separation factor of 15.6 to 25.1; H2/C3H8 separation factor of 38.0 to 57.8).3 Furthermore, a novel millisecond-etching reactor was developed to realize higher pore-density on graphene film, where concentrated etching medium generated high-density pore nucleation while minimized the pore expansion due to the short-time treatment, leading to attractive separation performance from single-layer graphene film with CO2 permeance of 2626 GPU and CO2/CH4 selectivity of 20 and CO2/N2 selectivity over 20. Overall, we demonstrate that graphene-based membranes are indeed capable of reaching the predicted high performance in gas separation.

References

(1) Wang, L.; Boutilier, M. S. H.; Kidambi, P. R.; Jang, D.; Hadjiconstantinou, N. G.; Karnik, R. Fundamental Transport Mechanisms, Fabrication and Potential Applications of Nanoporous Atomically Thin Membranes. Nature Nanotechnology 2017, 12, 509–522.

(2) Huang, S.; Dakhchoune, M.; Luo, W.; Oveisi, E.; He, G.; Rezaei, M.; Zhao, J.; Alexander, D. T. L.; Züttel, A.; Strano, M. S.; Agrawal, K. V. Single-Layer Graphene Membranes by Crack-Free Transfer for Gas Mixture Separation. Nature Communications 2018, 9, 1–11.

(3) Zhao, J.; He, G.; Huang, S.; Villalobos, L. F.; Dakhchoune, M.; Bassas, H.; Oveisi, E.; Agrawal, K. V. Etching Nanopores in Single-Layer Graphene with an Angstrom Precision for High-Performance Gas Separation. Science Advances 2019, 5, eaav1851.