Integration of polymerized ionic liquid with graphene for enhanced CO2 adsorption

Abstract

In this study, we have integrated an ionic liquid (IL) or polymerized ionic liquid (PIL) with graphene to demonstrate enhanced carbon dioxide adsorption properties. Graphene was non-covalently functionalized by IL or PIL, and the carbon dioxide adsorption and desorption properties were determined at low-pressures (<100 kPa). Upon functionalization, IL uniformly covers the graphene surface, while PIL forms highly distributed porous nanoparticles. The PIL functionalized graphene shows 22% higher adsorption capacity than graphene, while IL functionalization improves it only by 2%. This highlights the advantage of polymerizing the ionic liquid. Interestingly, the adsorption capacities of integrated system are higher than those of individual constituents (either graphene or IL or PIL). It is found that PIL functionalization offers more favorability of adsorption with a high adsorption energy. Isosteric heats of adsorption are calculated to be in the range of 18–28 kJ mol⁻¹, suggesting an ease of adsorbent regeneration. These results encourage the integration of PIL with other high surface area nanostructures for further improvement in the adsorption capacity.