Polyoxometalate-Based Metal–Organic Frameworks as Visible-Light-Induced Photocatalysts

Abstract

Two stable 3D polyoxometalate-based metal-organic frameworks (PMOFs), [Cu^I₁₂(trz)₈(H₂O)₂][α-SiW₁₂O₄₀]·2H₂O (1) and [Cu^I₁₂(trz)₈Cl][α-PW₁₂O₄₀] (2) (Htrz = 1- H-1,2,4-triazole) based on Keggin-type POMs were successfully obtained and fully characterized. The basic building units of the two PMOFs are [Cu^I₁₂(trz)₈], but polyoxoanion (POA) template effect leads to different structures and properties: 1 represents an interesting example that [α-SiW₁₂O₄₀]^4- locate in the nine-membered Cu-trz rings through Cu···O weak interactions to form a 3D framework, whereas 2 shows a 3D structure constructed from 2D bilayer cationic network [Cu^I₁₂(trz)₈Cl]³⁺ and [α-PW₁₂O₄₀]^3- lying in the adjacent layers via Cu···O weak interactions. PMOF 1 as unusual visible-light photocatalyst exhibit significantly enhanced photocatalytic activity under visible-light and excellent stability during the photocatalysis process for recovering and recycling, as well as photocatalytic hydrogen evolution activity.