Visible-light driven FexOy/TiO2/Au photocatalyst - synthesis, characterization and application for methyl orange photodegradation

A visible-light driven ternary photocatalyst of magnetic properties was prepared by a simple three-step synthesis. The Fe3O4 nanoparticles obtained by solvothermal method were covered with a layer of TiO2 by sol-gel procedure and amount of TiO2 in the shell around the magnetic core was increased by repetition of sol-gel runs. After calcination the composite was decorated with Au nanoparticles by photodeposition using a [AuClx(OH)(4-x)](-) complex as a gold precursor. The obtained binary (FexOy/TiO2) and ternary (FexOy/TiO2/Au) systems were characterized with the use of X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray (EDX) spectroscopic mapping. The photocatalytic activity of the systems with and without Au nanoparticles was studied in the reaction of methyl orange (MO) photodegradation under irradiation with visible light lamp and monochromatic diode (523 nm) to determine the role of TiO2 and Au nanoparticles in the photocatalytic process. The main species involved in the photocatalytic degradation of MO were determined with the use of reactive radical scavengers. The alternative core/shell composite FexOy/SiO2/TiO2/Au was prepared to determine the role of FexOy/TiO2 interface in the photocatalytic process. (C) 2020 Elsevier B.V. All rights reserved.