Ionic Liquid Functionalized Graphene for Carbon Dioxide Capture

Carbon emission becomes a serious global issue as it is the major contributor in earth warming. Carbon dioxide management is an emerging field of research to find economically viable ways to reduce the concentration in atmosphere. Herein, we report, the enhancement in carbon dioxide capture capacity of hydrogen exfoliated graphene due to the functionalization by ionic liquid, 1-Butyl-3-methylimidazolium tetrafluoroborate (HEG/[BMIM][BF₄]). Uniform functionalization has been attained by a simple method. Molecular vibrational spectral analysis confirms the composite nature of sorbent. Sorption analysis was carried out using sieverts apparatus. HEG/[BMIM][BF₄] shows sorption capacity of 42.32 mmol/g at 27 °C with 11.78 bar which is larger than that of graphene (21.6 mmol/g at nearly same conditions). This sorbent has capability to retain atleast 50% of initial sorption capacity even at 100 °C. Detailed analysis suggests that the enhancement in sorption capacity is due to the synergistic effect of physisorption by high surface area graphene and high CO₂ solubility in ionic liquid. Besides, CO₂ interacts reversibly with nitrogen functionalities present in imidazolium ring. The sorbent showed fast sorption kinetics along with high thermal stability.