Tailoring d‐Band Center of Single‐Atom Nickel Sites for Boosted Photocatalytic Reduction of Diluted CO2 from Flue Gas

Abstract Photocatalytic reduction of diluted CO 2 from anthropogenic sources holds tremendous potential for achieving carbon neutrality, while the huge barrier to forming *COOH key intermediate considerably limits catalytic effectiveness. Herein, via coordination engineering of atomically scattered Ni sites in conductive metal–organic frameworks (CMOFs), we propose a facile strategy for tailoring the d‐band center of metal active sites towards high‐efficiency photoreduction of diluted CO 2 . Under visible‐light irradiation in pure CO 2 , CMOFs with Ni‐O 4 sites (Ni‐O 4 CMOFs) exhibits an outstanding rate for CO generation of 13.3 μmol h −1 with a selectivity of 94.5 %, which is almost double that of its isostructural counterpart with traditional Ni‐N 4 sites (Ni‐N 4 CMOFs), outperforming most reported systems under comparable conditions. Interestingly, in simulated flue gas, the CO selectivity of Ni‐N 4 CMOFs decreases significantly while that of Ni‐O 4 CMOFs is mostly unchanged, signifying the supremacy for Ni‐O 4 CMOFs in leveraging anthropogenic diluted CO 2 . In situ spectroscopy and density functional theory (DFT) investigations demonstrate that O coordination can move the center of the Ni sites′ d‐band closer to the Fermi level, benefiting the generation of *COOH key intermediate as well as the desorption of *CO and hence leading to significantly boosted activity and selectivity for CO 2 ‐to‐CO photoreduction.