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

The selective capture of low-concentration CO2 from air or confined spaces remains a great challenge. In this study, various functional groups were introduced into UiO-66 to generate functionalized derivatives (UiO-66-R, R = NO2, NH2, OH, and CH3), aiming at significantly enhancing CO2 adsorption and separation efficiency. More significantly, UiO-66-NO2 and UiO-66-NH2 with high polarity exhibit exceptional CO2 affinity and optimal separation characteristics in mixed CO2/O2/N2 (1:21:78). In addition, the impressive stability of UiO-66-NO2 and UiO-66-NH2 endows them with excellent recycling stability. The effective adsorption and separation performances demonstrated by these two functional materials suggest their potential as promising physical adsorbents for capturing low-concentration CO2.