Methods for forming an ultrathin GO membrane are provided. The method can include: dispersing a single-layered graphene oxide powder in deionized water to form a single-layered graphene oxide dispersion; centrifuging the graphene oxide dispersion to remove aggregated graphene oxide material from the single-layered graphene oxide dispersion; thereafter, diluting the single-layered graphene oxide dispersion by about ten times or more through addition of deionized water to the graphene oxide dispersion; and thereafter, passing the single-layered graphene oxide dispersion through a substrate such that a graphene oxide membrane is formed on the substrate. Filtration membranes are also provided and can include: a graphene oxide membrane having a thickness of about 1.8 nm to about 180 nm, with the graphene oxide membrane comprises about 3 to about 30 layers of graphene oxide flakes.

A carbon molecular sieve (CMS) membrane is made by pyrolyzing a polymeric precursor membrane in a pyrolysis atmosphere containing a sulfur-containing compound.

A membrane-forming dope for carbon membranes, comprising polyphenylene oxide in an amount giving a concentration of 15 to 40 wt. % in the membrane-forming dope, and sulfur in an amount giving a ratio of 0.1 to 5.0 wt. %, preferably 0.2 to 3.0 wt. %, of the total weight of the polyphenylene oxide and the sulfur, both of which are dissolved in a solvent that can dissolve these components. A hollow fiber carbon membrane is produced by molding the membrane-forming dope for carbon membranes in a hollow shape by means of a wet or dry-wet spinning method using a double tubular nozzle, subjecting the molded product to an infusibilization treatment by heating at 150 to 350° C. in the air, and then subjecting it to a carbonization treatment by heating at 600 to 800° C. in an inert atmosphere or under vacuum. When the product molded in a hollow shape by means of a wet or dry-wet spinning method is subjected to an infusibilization treatment by heating in the air while stretching the product with a stress of 0.002 to 0.005 MPa, a hollow fiber carbon membrane having excellent gas permeability and a further high gas separation factor (He/CH.sub.4) can be obtained.

A separation membrane structure comprises a porous support, a first separation membrane formed on the porous support, and a second separation membrane formed on the first separation membrane. The first separation membrane has an average pore diameter of greater than or equal to 0.32 nm and less than or equal to 0.44 nm. The second separation membrane includes addition of at least one of a metal cation or a metal complex that tends to adsorb nitrogen in comparison to methane.

A method of forming a membrane is described. A graphenic-based membrane is formed on a growth substrate, where the graphenic-based membrane have one or more layers of graphenic-based material. The graphenic-based membrane is removed from the growth substrate. A region of the graphenic-based membrane having intrinsic or native defects is identified. The region of the graphenic-based membrane is irradiated with charged particles while introducing carbonaceous material on a surface of the one or more layers of graphenic-based material to heal the intrinsic or native defects.

Two-dimensional materials having apertures in their basal planes are described, where at least a portion of the apertures are occluded with a selectively introduced occluding moiety. Occluding moieties that pass into apertures function to occlude apertures. Composite membranes are described having a porous substrate with a two-dimensional material disposed on the membrane and covering only a portion of the pores, wherein at least a portion of uncovered substrate pores are occluded. Pore occlusion can be achieved by introduction of an occluding particle optionally followed by chemical reaction, deformation or swelling of the particle to facilitate occlusion of pores. Two-dimensional materials covering substrate pores can be size-selected and optionally functionalized providing for selective permeability through composite membranes. Methods for occluding defects and apertures in two-dimensional materials and for selectively occluding pores in composite membranes are provided. Selectively occluded materials and membranes are useful in filtration and other applications.

Two-dimensional materials, particularly graphene-based materials, having a plurality of apertures thereon can be formed into enclosures for various substances and introduced to an environment, particularly a biological environment (in vivo or in vitro). One or more selected substances can be released into the environment, one or more selected substances from the environment can enter the enclosure, one or more selected substances from the environment can be prevented from entering the enclosure, one or more selected substances can be retained within the enclosure, or combinations thereof. The enclosure can for example allow a sense-response paradigm to be realized. The enclosure can for example provide immunoisolation for materials, such as living cells, retained therein.

A method for the repair of defects in a graphene or other two-dimensional material through interfacial polymerization.

Provided herein are cross-linked graphene platelet polymers, compositions thereof, filtration devices comprising the cross-linked graphene platelet polymers and/or compositions thereof and method is using and making the same.

A two-dimensional membrane layered structure may include a support substrate layer having a plurality of substrate passages configured to allow fluid to flow therethrough, a two-dimensional membrane layer disposed on an upper surface of the support substrate layer, and a plurality of flow passages disposed between the support substrate layer and the two-dimensional membrane layer. The two-dimensional membrane layer may have a plurality of pores configured to allow fluid to flow therethrough. The plurality of pores may comprise a first portion of pores that overlap with the plurality of substrate passages and a second portion of pores that do not overlap with the plurality of substrate passages. The plurality of flow passages may be configured to allow fluid to flow through the second portion of pores to the plurality of substrate passages.