Engineering CALF-20/graphene oxide nanocomposites for enhancing CO2/N2 capture performance

Abstract

Ever-increasing atmospheric CO2 concentrations has necessitated the development of novel and cost-effective nanostructured composites with favorable physicochemical properties. Recently, the potential of metal-organic framework (MOF)-based nanocomposites towards boosting CO2 capture capability has become apparent indicating the importance of the relationship between their structure and properties. Herein, a novel nanocomposite of zinc-based CALF-20 MOF hybridized with graphene oxide is successfully fabricated using the solvothermal method. The construction of the well-structured nanocomposite is confirmed by performing PXRD, BET, FTIR, FESEM/EDX, TEM, and TGA characterization analyses. CO2 and N2 adsorption capacities and CO2/N2 separation performance of these nanocomposites are evaluated by experiment and mathematical modeling for the first time. The CALF-20/GO interfacial interaction and CO2 adsorption mechanisms are also discussed. As the best-performing adsorbent, the CALF-20 containing 20 wt% GO indicates a 42.6 % increment in CO2 uptake at 1.6 bar and a 32.7 % enhancement in CO2/N2 selectivity at 1 bar and 298 K and 1.28 times more CO2 retention time in a fixed bed column compared to that of the pristine MOF. The results show that the MOF and GO form chemical bonds at the interface resulting in generating new pore structures and increasing the porosity which are mostly responsible for boosting CO2 capture capacity. Interestingly, no meaningful effect is observed by the variation of the zinc atomic concentration at the surface. The simple synthesis procedure and understanding the interfacial structure of the novel CALF-20/GO composite as a promising adsorbent for CO2 capture applications can provide new insights for future work.