Direct Air Capture and Photoconversion of CO₂ to Ethylene by Defect-Tailored Cu₃-Based Metal-Organic Frameworks

The development of efficient direct air capture (DAC) systems coupled with photocatalytic CO₂ conversion is still an appealing challenge. Here, we engineered a series of defective Cu₃-based metal-organic frameworks (Cu₃-MOFs) for integrated atmospheric CO₂ capture and in situ photoreduction. The defective Cu₃-MOFs were constructed through selective removal of coordinated CO₃ ^2- from pristine MOFs with HCl etching, generating unsaturated Cu active sites for CO₂ harvesting, and the Cu₃-MOFs demonstrated enhanced CO₂ capture kinetics and capacity that compared to their pristine counterpart. Remarkably, the captured CO₂ could be directly photoreduced to C₂H₄ with an optimal production rate of 18.25 µmol·g^-1·h^-1 without additional photosensitizer or sacrificial agent. The experimental and theoretical results revealed that the defective sites not only facilitated CO₂ adsorption but also promoted C-C coupling of *CO intermediates, thereby enhancing C₂H₄ production. This work provides deep insights for designing advanced materials toward direct air-to-fuel conversion.