Tetrahedral UMOFNs/Ag₃PO₄ Core-Shell Photocatalysts for Enhanced Photocatalytic Activity under Visible Light

A new visible-light-responsive tetrahedral ultrathin metal-organic framework nanosheet (UMOFNs)/Ag₃PO₄ composite photocatalyst with a core-shell structure was readily synthesized by sonication in an organic solvent. Characterization methods for the photocatalyst included X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectroscopy. The XRD patterns of the composite photocatalyst before and after visible-light irradiation demonstrated that trace amounts of Ag ions in the composite photocatalyst easily transformed into Ag nanoparticles, which play a role in promoting charge separation at the interface of a heterojunction. The UMOFNs/Ag₃PO₄ composite photocatalyst showed higher photocatalytic activity for the photodegradation of 2-chlorophenol (2-CP) under visible-light irradiation (>420 nm) than Ag₃PO₄. The complete degradation of 2-CP was achieved in 7 min using the tetrahedral UMOFNs/Ag₃PO₄ core-shell photocatalyst, and the apparent reaction rate was approximately 26 times higher than that of pure Ag₃PO₄. Further, a scavenger experiment showed h⁺ and O₂ ^•- were the major reactive species involved in the photocatalytic reaction system. This enhanced photocatalytic activity results from the efficient separation of photoinduced electron-hole pairs and the increase of interface area between Ag₃PO₄, UMOFNs, and the Ag nanoparticles.