Promoting Carrier Separation in [W ₁₀ O ₃₂ ] ^4– -Doped POM@MOF Composites for Photocatalytic Oxidative Coupling of Amines

The integration of polyoxometalates (POMs) into metal–organic frameworks (MOFs) to construct composite photocatalysts represents a promising strategy for organic synthesis. The photosensitive [W 10 O 32 ] 4– clusters (noted as W 10 ) were assembled with the La-MOF framework at the molecular level, successfully constructing a series of W 10 @MOF composites. These materials not only endow La-MOF with visible-light absorption capacity but, more importantly, significantly promote the separation and migration efficiency of photogenerated electron–hole pairs. In the photocatalytic amine oxidation coupling reaction, W 10 @MOF-4, with the largest W 10 loading amount, exhibits excellent catalytic performance. Under mild conditions and without the need for an external oxidant, it achieves a benzylamine conversion rate of 98% and an imine selectivity of >99%, outperforming the single component and demonstrating a significant synergistic catalytic effect. Through systematic photoelectrochemical characterization, including photocurrent response, electrochemical impedance, and solid ultraviolet diffuse reflection analysis, it was confirmed that the introduction of W 10 effectively regulated the material’s energy band structure and significantly enhanced the interface charge separation efficiency as an electron capture center, providing a key mechanism basis for its outstanding photocatalytic performance.