Decimeter-Scale Atomically Thin Graphene Membranes for Gas-Liquid Separation

Graphene holds great potential for fabricating ultrathin selective membranes possessing high permeability without compromising selectivity and has attracted intensive interest in developing high-performance separation membranes for desalination, natural gas purification, hemodialysis, distillation, and other gas-liquid separation. However, the scalable and cost-effective synthesis of nanoporous graphene membranes, especially designing a method to produce an appropriate porous polymer substrate, remains very challenging. Here, we report a facile route to fabricate decimeter-scale (similar to 15 X 10 cm(2)) nanoporous atomically thin membranes (NATMs) via the direct casting of the porous polymer substrate onto graphene, which was produced by chemical vapor deposition (CVD). After the vapor-induced phase-inversion process under proper experimental conditions (60 degrees C and 60% humidity), the flexible nanoporous polymer substrate was formed. The resultant skin-free polymer substrate, which had the proper pore size and a uniform spongelike structure, provided enough mechanical support without reducing the permeance of the NATMs. It was demonstrated that after creating nanopores by the O-2 plasma treatment, the NATMs were salt-resistant and simultaneously showed 3-5 times higher gas (CO2) permeance than the state-of-the-art commercial polymeric membranes. Therefore, our work provides guidance for the technological developments of graphene-based membranes and bridges the gap between the laboratory-scale proof-of-concept and the practical applications of NATMs in the industry.

Automated summary

This study presents a facile method for fabricating nanoporous atomically thin membranes (NATMs) by directly casting a porous polymer substrate onto graphene. The resulting flexible nanoporous polymer substrate provides sufficient mechanical support without compromising the permeance of the NATMs. The NATMs, with proper pore size and a uniform spongelike structure, demonstrate salt resistance and 3-5 times higher gas permeance than commercial polymeric membranes, bridging the gap between laboratory-scale proof-of-concept and practical applications in the industry.