Highly Permeable Graphene Oxide/Polyelectrolytes Hybrid Thin Films for Enhanced CO₂/N₂ Separation Performance

Separation of CO₂ from other gasses offers environmental benefits since CO₂ gas is the main contributor to global warming. Recently, graphene oxide (GO) based gas separation membranes are of interest due to their selective barrier properties. However, maintaining selectivity without sacrificing permeance is still challenging. Herein, we described the preparation and characterization of nanoscale GO membranes for CO₂ separation with both high selectivity and permeance. The internal structure and thickness of the GO membranes were controlled by layer-by-layer (LbL) self-assembly. Polyelectrolyte layers are used as the supporting matrix and for facilitating CO₂ transport. Enhanced gas separation was achieved by adjusting pH of the GO solutions and by varying the number of GO layers to provide a pathway for CO₂ molecules. Separation performance strongly depends on the number of GO bilayers. The surfaces of the multilayered GO and polyelectrolyte films are characterized by atomic force microscopy and scanning electron microscopy. The (poly (diallyldimethylammonium chloride) (PDAC)/polystyrene sulfonate (PSS)) (GO/GO) multilayer membranes show a maximum CO₂/N₂ selectivity of 15.3 and a CO₂ permeance of 1175.0 GPU. LbL-assembled GO membranes are shown to be effective candidates for CO₂ separation based on their excellent CO₂/N₂ separation performance.