Engineering NH 2 -Cu-NH 2 Triple-atom Sites in Defective MOFs for Selective Overall Photoreduction of CO 2 into CH 3 COCH 3 .

Selective photoreduction of CO 2 to multicarbon products, is an important but challenging task, due to high CO 2 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-NH 2 for selective overall photo-reduction of CO 2 into acetone. The Cu 2+ site in well-modified CuN 2 O 2 units served as a trapping site to capture electrons via efficient electron-hole separation, forming the active Cu + site for CO 2 reduction. Two NH 2 groups in CuN 2 O 2 unit adsorb CO 2 and cooperated with copper ion to functionalize as a triple atom catalytic site, each interacting with one CO 2 molecule to strengthen the binding of *CO intermediate to the catalytic site. The deoxygenated *CO attached to the Cu site interacted with *CH 3 fixed at one amino group to form the key intermediate CO*-CH 3 , which interacted with the third reduction intermediate on another amino group to produce acetone. Our photocatalyst realizes efficient overall CO 2 reduction to C 3 product acetone CH 3 COCH 3 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 C 3 product from photosynthesis with water.