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.