Advance ternary surface-fluorinated TiO2 nanosheet/Ag3PO4/Ag composite photocatalyst with planar heterojunction and island Ag electron capture center

Abstract

Morphology, phase structure and optical performance of ternary surface-fluorinated TiO₂ nanosheet/Ag₃PO₄/Ag composite photocatalysts were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance spectroscopy (DRS). Wide band-gap TiO₂ crystal nanosheets were synthesized while stabilizing the {001} facet, which is highly active for oxidation reactions, with fluorination. Narrow band-gap Ag₃PO₄ crystal was then uniformly grown on a fluorinated-TiO₂ nanosheet {001} facet, forming a planar heterojunction between two nanosheet semiconductors. Ag particles were in situ reduced by visible light irradiation from Ag₃PO₄, forming island-distributed Ag on the Ag₃PO₄ surface. TiO₂/Ag₃PO₄/Ag exhibited excellent photocatalytic activity and high stability for methylene blue degradation under 410 nm LED light irradiation. The enhanced activities of TiO₂/Ag₃PO₄/Ag could be attributed to effective electron–hole separation, fast hole transportation and the Schottky barrier. This novel ternary TiO₂/Ag₃PO₄/Ag structure material is an ideal candidate in environmental treatment and cleaning applications.