Ag Nanoparticles Composited Ni(II)‐MOF for Enhancing Photocatalytic CO ₂ Reduction to CO

A series of Ag@NiX composite photocatalysts were successfully constructed via a chemical reduction strategy and applied to gas‐solid phase photocatalytic CO ₂ reduction without additional photosensitizer using H ₂ O as sacrificial agent. The introduction of Ag nanoparticles (Ag NPs) on a Ni‐MOF, namely [Ni ₂ (tipe)(cca) ₂ (H ₂ O) ₂ ] ·2DMF·2H ₂ O ( NiX ) (tipe = 1,1,2,2‐ tetrakis (4‐(1H‐imidazol‐1‐yl)phenyl)ethene, H ₂ cca = 4‐carboxycinnamic acid), effectively enhanced visible‐light absorption capability of the composites and promoted separation and migration of photogenerated charge carriers. Among the prepared samples, Ag@NiX‐2 exhibited optimal photocatalytic performance and achieved a CO production rate of 14.7 μmol g ⁻¹ in 5 h. In situ FT‐IR measurements revealed the formation of key intermediate *COOH during the CO ₂ photoreduction process, thereby elucidating the reaction pathway. Theoretical calculations showed that an interfacial charge transfer occurs between Ag NPs and NiX in the Ag@NiX composite, thus reducing the reaction Gibbs free energy. This study offers a feasible approach for rational development of MOF‐based composite photocatalysts toward efficient photocatalytic CO ₂ reduction.