Generating nano-incised graphene kirigami membrane via selective tearing

By virtue of its single-layer thickness, nanoscale incisions and flexible structure, graphene kirigami (GK) owns a great prospect to be an ultra-permeable membrane for separation engineering. However, the difficulty in creating nanoscale incisions has prevented GK from being considered as a membrane candidate in the past. This situation has been improved recently by some emerging kirigami-inspired synthetic strategies and techniques for con-structing complex three-dimensional nanostructures. Here, we reveal the potential fabrication of nano-incised GK membranes via an innovative selective tearing method using molecular dynamics simulation. The results exhibit that through the selective tearing method, the periodic wrinkles could be generated on the defective graphene, contributing to the stress concentration around the defects and causing the C-C bonds to break, finally forming nano-incisions. The initial defective graphene, including its size, defects density, parallelogram angle and aspect ratio, as well as the shear angle, are crucial to the incision distribution on the formed GK-like membrane after selecting tearing treatment. The desalination simulation demonstrates that the selective tearing formed graphene kirigami (STGK) membrane has ultra-high water permeability, achieving 1197 L/m2/h/bar with 100 % salt rejection, 5.2-6.3 times higher than the previously reported nanoporous graphene and more than two orders of magnitude higher than current reverse osmosis membranes. We expect this work will inspire the next-generation membranes for separation and purification technology.

Automated summary

By using a selective tearing method, nano-incised graphene kirigami (STGK) membranes with ultra-high water permeability have been fabricated. The results show that periodic wrinkles can be generated on defective graphene through the selective tearing method, leading to the breakage of C-C bonds and the formation of nano-incisions. The desalination simulation demonstrates that the STGK membrane achieves a water permeability of 1197 L/m2/h/bar with 100% salt rejection, surpassing nanoporous graphene and current reverse osmosis membranes by 5.2-6.3 times and more than two orders of magnitude, respectively. This work is expected to inspire the development of next-generation separation and purification membranes.