Isolation, Architecture of Ag8-Cluster Modified Polyoxometalate for Water Reduction into Hydrogen Driven by Visible Light

To alleviate the shortage of oil resources, photocatalytic water decomposition into hydrogen (H₂) is an efficient method to produce clean and green energy with the potential to replace oil in many fields. Under hydrothermal conditions, two Strandberg-type phosphomolybdates were synthesized, formulated as [Ag₄(C₈H₆N₂)₆H₂O][H₂P₂Mo₅O₂₃]·1H₂O (1) and [Ag(C₄H₄N₂)]₈[H₂P₂Mo₅O₂₃]₂·11H₂O (2), based on MoO₃, Ag(NO₃)₃, H₃PO₄ and two N-containing organic ligands (quinoxaline and pyridazine). The single-crystal structure analysis indicates that compound 1 showed one-dimensional chain constructed from [Ag₃(C₈H₆N₂)₄]³⁺, [Ag(C₈H₆N₂)₂]⁺ cations and [H₂P₂Mo₅O₂₃]^4- anions, while compound 2 features a two-dimensional-layered structure formed by interesting [Ag(C₄H₄N₂)O]₈ clusters connecting [H₂P₂Mo₅O₂₃]^4- anions. Under visible light irradiation, both compounds showed excellent performance in hydrogen production. After 8 h of visible light irradiation, the H₂ yields were 243.6 (1) and 401.1 (2) μmol, which have wide application prospects in the photocatalysis field. Meanwhile, comparative experiments showed that the Ag⁺ ions significantly promoted hydrogen production under visible light, serving as a crucial active center in the photocatalytic water decomposition into the hydrogen process.