Bottom-up synthesis of two-dimensional composite via CuBDC-ns growth on multilayered MoS2 to boost CO2 permeability and selectivity in Pebax-based mixed matrix membranes

Abstract In order to conquer the obstacle that increased CO2 selectivity in two-dimensional nanosheet incorporated-mixed matrix membranes (MMM) is accompanied with sacrifice of CO2 permeability, CuBDC-ns was grown on multilayered MoS2 nanosheets via bottom-up synthesis strategy to obtain two-dimensional nanosheet composite, which was incorporated into Pebax-based MMM for efficient CO2 separation. The synthesized CuBDC-ns@MoS2 composite with abundant unsaturated metal sites (Cu-S and Cu-O) achieve superior CO2 adsorption capacity compared to pristine CuBDC-ns. This is attributed to formation of coordination complex between Cu ions on CuBDC-ns and S atoms in multilayered MoS2 nanosheets, as revealed on FTIR and XPS analysis. Therefore, the incorporated CuBDC-ns@MoS2 composites not only increase CO2 separation selectivity via lamellar morphology and narrow pore aperture, but also enhance CO2 solubility and diffusivity via coordination complex and unsaturated metal sites, boosting CO2 permeability and separation selectivity simultaneously. Gas permeation experiments demonstrate that Pebax-based MMMs incorporated with 2.5 wt.% of CuBDC-ns@10MoS2 composite achieve CO2 permeability of 123 Barrers, as well as superior CO2/CH4 and CO2/N2 selectivities of 18 and 69. They are higher by 42.5 %, 19.2 %, and 80.2 %, respectively, than those of pristine Pebax membrane.