Synthesis and characterization of core–shell–shell magnetic (CoFe2O4–SiO2–TiO2) nanocomposites and TiO2 nanoparticles for the evaluation of photocatalytic activity under UV and visible irradiation

Abstract

Magnetic TiO₂–SiO₂–CoFe₂O₄ (TSC) composite photocatalytic particles with a core–shell structure and a high crystalline anatase TiO₂ shell were synthesized via controlled hydrolysis and condensation of titanium isopropoxide. Nano-sized TiO₂ powders were synthesized by a sol–gel/hydrothermal route. The prepared TiO₂ and its composites were characterized by XRD, SEM, TEM, FT-IR, VSM, and UV-Vis. The results show that the obtained TSC composite particles were composed of spherical nanoparticles, about 5–8 nm in diameter, with several CoFe₂O₄ fine particles as cores and silica as coatings and barrier layers between the magnetic cores and anatase titania shells. The average crystallite size of TiO₂ nanoparticles with an anatase structure is 6 nm. The photocatalytic activities of the samples were evaluated by the photocatalytic degradation of dichlorophenol-indophenol (DCPIP) dye. The maximum level reached for the degradation of the dye molecule was 95.32 and 87.27% for 3 minutes under UV and visible light respectively for mesoporous TiO₂ nanoparticles.