Integrated CO2 Capture and Conversion by a Robust Cu(I)-Based Metal–Organic Framework

Metal–organic frameworks (MOFs) have shown promise in both capturing CO2 under flue gas conditions and converting it into valuable chemicals. However, the development of a single MOF capable of capturing and selectively converting CO2 has remained elusive due to a lack of a harmonious combination of selectivity, water stability, and reactivity. For example, Cu(I)-based MOFs are particularly effective for CO2 conversion, but they do not typically exhibit selective CO2 adsorption and often suffer from instability in the presence of air and moisture. Developing a Cu(I) MOF that is stable under flue gas conditions while also capturing CO2 from this mixture would likely afford a material capable of selectively capturing and converting CO2 in an integrated pathway, which would represent a significant advancement in this field. In this study, we introduce NU-2100, an ultramicroporous Cu(I) MOF, which exhibits both selectivity for CO2 adsorption and great stability even in the presence of moisture and air. Comprehensive evaluations involving exposure to air, oxygen, water, and varying temperatures reveal that NU-2100 demonstrates superior stability compared to other known Cu(I) MOFs. Utilizing adsorption isotherms and thermogravimetric analysis coupled with gas chromatography–mass spectrometry (TGA-GCMS), we establish the high selectivity of NU-2100 for CO2 over common flue gas components, including water, nitrogen, and oxygen. Additionally, under mild reaction conditions (50 °C and H2:CO2 = 3:1), NU-2100 exhibits CO2 capture and catalytic conversion to formic acid with 100% selectivity. This study marks an important step toward the design of next-generation MOFs capable of integrated carbon capture and utilization (iCCU) under industrial conditions.