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

Abstract 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 [MoOS 3 ] 2− unit is introduced into the Cu I clusters to form a series of atomically‐precise Mo VI −Cu I bimetallic clusters of [Cu 6 (MoOS 3 ) 2 (C 6 H 5 (CH 2 )S) 2 (P(C 6 H 4 − R ) 3 ) 4 ] ⋅ x CH 3 CN ( R =H, CH 3 , 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 Fe 3 O 4 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.