Integrating Multifunctionalities into a Three‐Dimensional Covalent Organic Framework for Efficient CO2 Photoreduction

Fabrication of highly efficient photocatalysts for CO2 conversion is still challenging. Herein, integrating nitrogen‐rich organic cages and the photoactive porphyrin moieties together, a three‐dimensional (3D) covalent organic framework (COF), Cage‐PorCOF, is successfully synthesized. After incorporating metal ions (Co2+ and Ni2+) into the cage‐based COF, Cage‐PorCOF(Co) and Cage‐PorCOF(Ni) are subsequently constructed for the CO2 photoreduction. Catalytic experiments show impressive performance in CO2 photoreduction with CO generation rates of up to 48,748 and 28,446 μmol g−1 h−1 in the first initiating hour for Cage‐PorCOF(Co) and Cage‐PorCOF(Ni) respectively, which is attributed to the synergistic effects from CO2‐affinity of the porous frameworks and incorporated metal atoms, the light‐absorption and charge separation ability of metalloporphyrin groups as well as the fully exposed single‐atomic catalytic sites confirmed by both experimental and theoretical analyses. This study demonstrates that by the integration of multiple functionalities into 3D porous solids, highly effective photocatalysts for CO2 conversion can be achieved.