Directing the Two-Dimensional Assembly of Polyoxometalates via Surface Chemistry

The controlled assembly of polyoxometalate (POM) clusters into ordered superstructures offers a powerful route to developing advanced catalysts. However, it remains unclear how the surface properties of POM clusters govern the assembly process and affect their catalytic performance. In this study, we precisely modulate the surface chemistry of POM clusters via mono- and di-Mn substitution, thereby directing the selective assembly of two nanosheet (NS) superstructures with hexagonal and oblique symmetries, respectively. In direct electro-epoxidation of propylene, the Mn₂PW₁₀ NS demonstrates markedly enhanced performance, with the Faraday efficiency increased by 4.4 times compared to the MnPW₁₁ NS. Density functional theory calculations and molecular dynamics simulations reveal that incorporating metals into the POM framework modulates surface charge and ligand orientation, thereby directing the formation of distinct superstructures. Collision dynamics analyses further reveal that the surface ligand distribution affects reactant adsorption and diffusion, consequently affecting catalytic activity. This work not only establishes cluster surface engineering as a powerful strategy for constructing tailored subnanometric assemblies, but also provides deep insight into how the surface characteristics of these assemblies govern catalytic behavior.