Dual Regulation of Sensitizers and Cluster Catalysts in Metal–Organic Frameworks to Boost H₂ Evolution

Photocatalytic efficiency is closely correlated to visible-light absorption ability, electron transfer efficiency and catalytic center activity of photocatalysts, nevertheless, the concurrent management of these factors to improve photocatalytic efficiency remains underexplored. Herein, we proposed a sensitizer/catalyst dual regulation strategy on the polyoxometalate@Metal-Organic Framework (POM@MOF) molecular platform to construct highly efficient photocatalysts. Impressively, Ni-Sb₉@UiO-Ir-C6, obtained by coupling strong sensitizing [Ir(coumarin 6)₂(bpy)]⁺ with Ni-Sb₉ POM with extremely exposed nickel site [NiO₃(H₂O)₃], can drive H₂ evolution with a turnover number of 326923, representing a record value among all the POM@MOF composite photocatalysts. This performance is over 34 times higher than that of the typical Ni₄P₂@UiO-Ir constructed from [Ir(ppy)₂(bpy)]⁺ and Ni₄P₂ POM. Systematical investigations revealed that dual regulation of sensitizing and catalytic centers endowed Ni-Sb₉@UiO-Ir-C6 with strong visible-light absorption, efficient inter-component electron transfer and high catalytic activity to concurrently promote H₂ evolution. This work opens up a new avenue to develop highly active POM@MOF photocatalysts by dual regulation of sensitizing/catalytic centers at the molecular level.