Ultrathin, Molecular-Sieving Graphene Oxide Membranes for Selective Hydrogen Separation

Abstract

Ultrathin, molecular-sieving membranes have great potential to realize high-flux, high-selectivity mixture separation at low energy cost. Current microporous membranes [pore size < 1 nanometer (nm)], however, are usually relatively thick. With the use of current membrane materials and techniques, it is difficult to prepare microporous membranes thinner than 20 nm without introducing extra defects. Here, we report ultrathin graphene oxide (GO) membranes, with thickness approaching 1.8 nm, prepared by a facile filtration process. These membranes showed mixture separation selectivities as high as 3400 and 900 for H2/CO2 and H2/N2 mixtures, respectively, through selective structural defects on GO.

Self-assembled two-dimensional nanofluidic proton channels with high thermal stability

“…These high aspect ratio 2D sheets, regardless of material composition, have a unique advantage over other morphologies in that they are the only shape that can stack to yield continuous interstitial space, which is both percolated throughout the material and highly uniform in size and orientation. This offers unprecedented opportunity to construct nanofluidic channels to study molecular transport [9][10][11][12] . The width of such lamellar channels is comparable to the apparent thickness of the 2D sheets, and typically can be adjusted from around half a nanometre to several nanometres.…”

Impermeable barrier films and protective coatings based on reduced graphene oxide

“…In this respect, GO is particularly attractive because multilayer films can be produced easily and relatively cheaply by depositing GO solutions on various substrates by spraying, and dip-or rod-coating, and so on. The resulting GO laminates are shown to exhibit highly unusual permeation properties [5][6][7][8] . In the dry state, they are impermeable even for helium but, under humid conditions, provide no barrier for water vapour 5 .…”

“…M embranes made from graphene and its chemical derivative called graphene oxide [1][2][3] (GO) show a range of unique barrier properties [4][5][6][7][8] . Defect-free monolayer graphene is impermeable to all gases and liquids 4 and, similar to graphite, shows high chemical and thermal stability with little toxicity.…”

Graphene opens up to new applications

“…A number of theoretical studies have suggested that the selectivity and permeability of such membranes could be vastly superior to the polymerbased filtration membranes that are typically used today [1][2][3] . And in the past few years, experimental demonstrations of the potential of nanoporous graphene membranes have begun to emerge [4][5][6][7][8][9] .…”

“…Alternatively, layered graphene and graphene oxide membranes have been shown to separate carbon dioxide from nitrogen, suggesting that the approach might be of value in carbon capture applications 5 . Similarly, membranes made from two or three layers of graphene oxide can separate hydrogen from carbon dioxide and nitrogen 6 .…”