Construction of Terminal Exposed Ti Active Sites Based on Aluminum Oxo Cluster Supports for Visible-Light-Driven CO₂...

Maximize the exposure of Ti active sites in titanium-oxo clusters (TOCs) has been considered as the key to highly efficient photocatalytic CO₂ reduction. However, the fast aggregation rate of Ti⁴⁺ greatly limits its realization. Herein, we reported a universal strategy to precisely immobilize and disperse Ti via aluminum oxo clusters (AlOCs) supports. Leveraging the coordination-delay effects of alcohol solvents to modulate the differentiated aggregation kinetics of Ti⁴⁺ and Al³⁺, we successfully induced the priority assembly of Al³⁺ into AlOC supports, and further immobilized Ti on it in a terminal-exposed mode. Based on this strategy, we successfully synthesized a structural well-defined Ti₄Al₆ cluster, which featured a natural θ-Al₂O₃-like support. This support platform can be readily modified for functionalization (such as incorporation of ferrocene) or realizing single Ti dispersity. The optimal catalyst, Ti₂Al₄-Fc (featuring a γ-Al₂O₃-like support, Fc = ferrocenecarboxylate) realized a high Ti turnover frequency of 2.4 h^-1 in visible-light-driven CO₂ photoreduction, significantly higher than many reported Ti-based photocatalysts. This work provides a new paradigm for designing metal-oxo cluster-based photocatalysts with atomic dispersity and high atomic utilization.