Enhanced CO2 capture and selectivity in metal–organic frameworks through ionic liquid modification: Synthesis, characterization, and performance evaluation

Abstract

The increasing threats from CO2 emissions demand advanced materials for effective CO2 capture. This study presents a method to enhance the metal–organic framework (MOF) UTSA-16 (Co) by incorporating the ionic liquid (IL) 1-n‑butyl‑3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) using one-pot microwave-assisted synthesis. Fourier-transform infrared spectroscopy (FTIR) identified [BF4]- anions between IL and UTSA-16 (Co), suggesting improved CO2 adsorption sites. Electron microscopy and X-ray diffraction (XRD) confirmed the preservation of morphology and crystallinity of UTSA-16 (Co) after IL incorporation. Even though the Brunauer−Emmett−Teller (BET) analysis showed a slight surface area reduction from 792 m²/g to 714 m²/g, the MOF/IL composite increased CO2 capture capacity by 17 % (5.35 mmol/g) and CO2/N2 selectivity by 27 % (127) compared to the pristine MOF, due to the synergistic effect of MOF and IL. The composite demonstrated excellent moisture stability, with only a 4 % decrease in adsorption capacity (5.11 mmol/g) after 10 days in humid air. Recyclability tests showed unchanged capture capacity over 10 adsorption-desorption cycles, confirming the material's stability and reusability. These findings present promising avenues for advancing MOF/IL composites tailored for efficient carbon-capture applications. © 2025 The Author(s)