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 (∼15 × 10 cm2)
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 °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 O2 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.