Substituent Effect to Fine-Tune Energy Levels of Atom-Precise [MoOS3]2- Modified Copper(I) Thiolate Clusters Boosting Recyclable Photocatalysis

The propulsion of photocatalytic hydrogen (H-2) production is limited by the rational design and regulation of catalysts with precise structures and excellent activities. In this work, the [MoOS3](2-) unit is introduced into the Cu-I clusters to form a series of atomically-precise Mo-VI-C-uI bimetallic clusters of [Cu-6(MoOS3)(2)(C6H5(CH2)S)(2)(P(C6H4-R)(3))(4)] center dot xCH(3)CN (R=H, CH3, or F), which show high photocatalytic H-2 evolution activities and excellent stability. By electron push-pull effects of the surface ligand, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of these Mo-VI-Cu-I clusters can be finely tuned, promoting the resultant visible-light-driven H-2 evolution performance. Furthermore, Mo-VI-Cu-I clusters loaded onto the surface of magnetic Fe3O4 carriers significantly reduced the loss of catalysts in the collection process, efficiently addressing the recycling issues of such small cluster-based catalyst. This work not only highlights a competitively universal approach on the design of high-efficiency cluster photocatalysts for energy conversion, but also makes it feasible to manipulate the catalytic performance of clusters through a rational substituent strategy.