Effect of Functional Groups on Low-Concentration Carbon Dioxide Capture in UiO-66-Type Metal-Organic Frameworks

The incorporation of polar functionalgroups into UiO-66 permits control over the pore sizeand environment,resulting in increased interaction between UiO-66 derivatives andCO(2). Ultimately, this modification enhances the separationperformance of trace levels of CO2. The selective capture of low-concentration CO2 fromair or confined spaces remains a great challenge. In this study, variousfunctional groups were introduced into UiO-66 to generatefunctionalized derivatives (UiO-66-R, R = NO ( 2 ), NH ( 2 ), OH, and CH ( 3 )), aiming at significantly enhancing CO2 adsorption andseparation efficiency. More significantly, UiO-66-NO ( 2 ) and UiO-66-NH ( 2 ) with high polarity exhibit exceptional CO2 affinityand optimal separation characteristics in mixed CO2/O-2/N-2 (1:21:78). In addition, the impressive stabilityof UiO-66-NO ( 2 ) and UiO-66-NH ( 2 ) endows them with excellent recycling stability.The effective adsorption and separation performances demonstratedby these two functional materials suggest their potential as promisingphysical adsorbents for capturing low-concentration CO2.