Significance of Silica Inter layer in Magnetic Photocatalyst Having γ-Fe2O3 as a Magnetic Ceramic Core

Anatase-titania (TiO2)-coated maghemite (gamma-Fe2O3) nanocomposite magnetic photocatalysts have been synthesized without and with the interlayer of silica (SiO2)-coating. The combination of modified Stober and sol-gel methods involving the alkoxide-precursors has been employed for the processing of magnetic photocatalysts. The morphological, chemical, and structural analyses of the magnetic photocatalysts have been carried out using the various techniques such as the transmission electron microscope (TEM), selected-area electron diffraction (SAED), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). The photocatalytic activities of magnetic photocatalysts, prepared without and with the SiO2 interlayer, have been measured under the ultraviolet (UV) radiation exposure using the methylene blue (MB) as a model catalytic dye-agent. The concentration free-hydroxyl radicals (OH center dot) generated by the magnetic photocatalysts, under the UV-radiation exposure, has been qualitatively measured via the OHS-trapping experiments using the photoluminescence (PL) spectrofluorometer. The amount of photo-dissolution of magnetic ceramic core, under the UV-radiation exposure, has been measured via the inductively coupled plasma atomic emission spectroscope (ICP-AES). It has been shown that the SiO2-coaitng as an interlayer between the anatase-TiO2 shell and gamma-Fe2O3 magnetic ceramic core plays a crucial role in controlling the number of parameters which directly affect the performance of nanocomposite particles as magnetic photocatalyst. As a result of the combined effect of all these factors, the best nanocomposite magnetic photocatalyst has been observed to be the anatase-TiO2-coated SiO2/gamma-Fe2O3 (cycle-5).