Direct Air Capture and Photoconversion of CO ₂ to Ethylene by Defect‐Tailored Cu ₃ ‐Based Metal–Organic Frameworks

Abstract The development of efficient direct air capture (DAC) systems coupled with photocatalytic CO 2 conversion is still an appealing challenge. Here, we engineered a series of defective Cu 3 ‐based metal–organic frameworks (Cu 3 ‐MOFs) for integrated atmospheric CO 2 capture and in situ photoreduction. The defective Cu 3 ‐MOFs were constructed through selective removal of coordinated CO 3 2− from pristine MOFs with HCl etching, generating unsaturated Cu active sites for CO 2 harvesting, and the Cu 3 ‐MOFs demonstrated enhanced CO 2 capture kinetics and capacity that compared to their pristine counterpart. Remarkably, the captured CO 2 could be directly photoreduced to C 2 H 4 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 CO 2 adsorption but also promoted C–C coupling of *CO intermediates, thereby enhancing C 2 H 4 production. This work provides deep insights for designing advanced materials toward direct air‐to‐fuel conversion.