Engineering NH₂-Cu-NH₂ Triple-atom Sites in Defective MOFs for Selective Overall Photoreduction of CO₂ into CH₃COCH₃

Selective photoreduction of CO₂ to multicarbon products, is an important but challenging task, due to high CO₂ activation barriers and insufficient catalytic sites for C-C coupling. Herein, a defect engineering strategy for incorporating copper sites into the connected nodes of defective metal-organic framework UiO-66-NH₂ for selective overall photo-reduction of CO₂ into acetone. The Cu²⁺ site in well-modified CuN₂O₂ units served as a trapping site to capture electrons via efficient electron-hole separation, forming the active Cu⁺ site for CO₂ reduction. Two NH₂ groups in CuN₂O₂ unit adsorb CO₂ and cooperated with copper ion to functionalize as a triple atom catalytic site, each interacting with one CO₂ molecule to strengthen the binding of *CO intermediate to the catalytic site. The deoxygenated *CO attached to the Cu site interacted with *CH₃ fixed at one amino group to form the key intermediate CO*-CH₃, which interacted with the third reduction intermediate on another amino group to produce acetone. Our photocatalyst realizes efficient overall CO₂ reduction to C₃ product acetone CH₃COCH₃ with an evolution rate of 70.9 μmol g_cat ^-1 h^-1 and a selectivity up to 97 % without any adducts, offering a promising avenue for designing triple-atomic sites to producing C₃ product from photosynthesis with water.