Ni-Metalized Covalent Organic Cage as a Photocatalyst for Selective Photoreduction of CO2 to CO.

Metal complex-based photocatalysts are promising for CO₂ reduction. Their catalytic performances greatly rely on the synergy of ligands and metal ions. Here, we demonstrate an assembly of covalent organic cage (COC) and metal ions for photocatalytic CO₂ reduction. The coordinated metal serves as catalytically active site for CO₂ reduction, while the cage not only chelates the metal site, but also enhances the local concentration of CO₂ around metal site, and decreases the key intermediate reaction energy barrier, thereby promoting the CO₂ reduction reaction kinetically and thermodynamically. Accordingly, a Ni metalized COC exhibited outstanding photocatalytic performance in CO₂-to-CO conversion under visible light irradiation. This study highlights the feasibility and advantage of organic cages for the construction of photocatalysts for artificial photosynthesis.