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

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.