Impermeability of graphene and its applications

This review discusses the genesis of impermeability in graphene and its extraordinary applications in fluid-encasement for wet electron-microscopy, selective gas-permeation, nanopore-bio-diffusion, and barrier coating against rusting and environmental hazards. As the thinnest material, graphene is composed of sp2 hybridized carbon atoms linked to one another in a 2D honeycomb lattice with high electron-density in its aromatic rings, which blocks-off all molecules. This phenomena, in combination with its strong structure (C–C bond energy = 4.9 eV and intrinsic strength = 43 N/m) makes graphene the most impermeable membrane (thinnest membrane that is impermeable). Apart from the applications mentioned above, graphene coatings have enabled fundamental studies on chemical processes and fluid structures. For example, graphene can allow electron imaging of nanocrystal nucleation process and water-lattice-structure due to its impermeability. Along with being the strongest, most conductive, and optically-absorbing material (∼2.3% optical absorbance), graphene’s impermeability opens a wide range of exciting opportunities.