Unusual CO2 Transport Through Ultrathin Graphene Oxide Membranes

In general, two-dimensional layered materials such as clays have been regards as a barrier material for gas permeation when they are combined with gas permeable polymeric materials. Therefore they are seldom considered as a membrane material for gas separation. Recently, two dimensional graphene with one atom-thick sheet and its derivatives (e.g., graphene oxide (GO) and reduced GO) have gained tremendous interest in physical and chemical community owing to its versatile usefulness. More recently, membranologists have also showed lots of interest because its ultrathin thickness and its probable availability in porous geometry will be suitable for preparing the most ideal membrane materials. Recently our group has demonstrated scalable, ultrathin GO membranes combined with commercially available microporous polymeric membranes. Here we have observed many interesting gas separation behavior, particular CO₂ separations. The CO₂ permeability and selectivity in such ultrathin GO membranes could be engineered by changing original GO flake size, coating methods and by further physical and chemical modifications. In addition, GO membranes have great advantages over conventional nanoporous carbon membranes derived from inert pyrolysis of thermosetting polymeric precursor because it can be scalably prepared from solution. In this paper, gas transport behaviors depending on the layered stacking structure and affinities between GO sheets and CO₂ gas will be explained in detail.