Preparation and photocatalytic activity of magnetic samarium-doped mesoporous titanium dioxide at the decomposition of methylene blue under visible light

Preparation of samarium-doped mesoporous titanium dioxide (Sm/MTiO₂) coated magnetite (Fe₃O₄) photocatalysts (Sm/MTiO₂/Fe₃O₄) and their activities under visible light were reported. The catalysts with Sm/MTiO₂ shell and a Fe₃O₄ core were prepared by coating photoactive Sm/MTiO₂ onto a magnetic Fe₃O₄ core through the hydrolysis of tetrabutyltitanate (Ti(OBu)₄, TBT) with precursors of Sm(NO₃)₃ and TBT in the presence of Fe₃O₄ nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO₂ was tightly bound to Fe₃O₄ and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.