Electronic State Modulation of a Single‐Cu Site on a Bimetallically Doped Titanium‐Oxo Cluster to Enhance CO2 Storage

While atomically monodisperse nanostructured materials with controllable heterometal dopants are highly desirable to unravel the structure‐catalysis relationships, their controlled synthesis and atomic‐level structural determination remain significant challenges. Here, we report on nanosized titanium‐oxo clusters featuring two heterometallic sites, Ti10M2O8Sal6(HSal)2(OCH3)16(CH3OH)4 (denoted as TiM2; M2 = MnCu, CaCu, Cu2, Mn2, Ca2; Sal and HSal represent salicylate and 2‐hydroxybenzoate, respectively), which were used for catalyzing and photocatalyzing the CO2/epoxide cycloaddition to synthesize cyclic carbonates. Notably, the valence state of Cu is modulated by Mn in the TiMnCu cluster as Cu exists in the δ+ valence (1 < δ < 2), whereas in TiCu2 and TiCaCu, Cu is +2 valence. TiMnCu exhibited the highest catalytic activity and selectivity with 1 atm CO2, and also effective activity using simulated flue gas. Experiments and density functional theory simulations revealed that CO₂ activation is the rate‐determining step, with the reduced valence of Cu promoting CO₂ activation and positioning the adsorbed CO₂ closer to the epoxide, thereby facilitating the cyclization process. Our study underscores that in metal‐oxide supports with heterometal centers, the modulation of electronic states by the different heterometals can significantly enhance catalytic performance.