CO2 sponge from plasma enhanced seeded growth of metal organic frameworks across carbon nanotube bucky-papers

In this study, a novel hybrid metal organic framework (MOF) - bucky-paper was developed by seeding crystal growth of Mg-MOF-74 from the surface of carbon nanotube (CNT) mats, called bucky-papers (BP). The seeding density and growth kinetics of the MOF crystals across the CNT-BPs was enhanced through continuous discharge plasma treatments with either O2/Ar or NH3 gas streams. X ray Photo-electron Spectroscopy measurements were used to demonstrate the impact of the plasma treatment on the anchoring of hydroxyl, amine and carbonyl functional groups to the graphitic surfaces, resulting in higher surface wettability and greater MOF seeding densities. CO2 adsorption isotherms at 25 °C showed a large increase in CO2 uptake (maximum of 10.70 mmol CO2/g) for MOF-CNT-BP samples compared to virgin CNT-BP (0.35 mmol CO2/g) or parent Mg-MOF-74 (maximum of 3.13 mmol CO2/g). Higher CO2 adsorption of MOF-CNT-BP sponges were attributed to the synergistic effect between the MOF and CNT due to increased porosity at the interface, better MOF crystal distribution, and enhanced dispersive forces which improve structural integrity of MOF component.