Magnetic nano composites on the basis of TiO2 Fe3O4
The photochemical catalysis based on titanium dioxide attracts a lot of attention by its ability to conserve non-polluting medium, to be used in luminescent materials, solar batteries, gas sensor indicators and in the field of medicine. Titanium dioxide is an n-type semiconductor with a wide energy band gap exhibiting photocatalytic activity. While Ti02 can be easily involved in every mentioned application, it cannot be extracted because it is an electrical insulator. In order to separate the photocatalyst from the reaction media, composite particles can be fabricated in the form of magnetic cores with a photo catalytic shell. The design of magnetic core-TiO2 shell structures was investigated by a number of researchers.
Results confirm high efficiency and convenience of skilled application of core-shell type microsphere Fe3O4: TiO2 to capture phosphopeptides and MS MALDI-TOF analysis. Magnetic nanoparticles Fe3O4: TiO2 not only possess the ability to capture some pathogenic bacteria but also effectively suppress bacteria cells growth appearing during a short time under the influence of ultra-violet lamp of low power. To cover magnetite with titanium dioxide is rather difficult, low TiO2 crystallinity being the reason of its low photo activity. High-heat treatment was used to avoid this difficulty. Though it should be noted that super paramagnet can turn into y-Fe3O4 ferromagnet or a- Fe3O4 paramagnet during high-heat treatment of magnetic cores Fe3O4.
Magnetic nanocomposite core-shell type Fe3O4: TiO2 was prepared by a new non-thermal method of magnetite nanoparticles encapsulation in anatase titanium dioxide. A pure anatase and nanoparticles magnetite phase was independently prepared with the help of sol-gel methods. VSM, XRD, SEM and EDX TEM analyses confirmed that the magnetic phase was formed on the magnetite and TiO2 shell regularly covers Fe3O4 with a thin layer though only due to the forces of adhesion. Besides, no chemical reaction between TiO2 and Fe3O4 proceeds that was confirmed by X-ray diffraction method. TEM and SAM images showed that core had the shape of ellipsoids with an average size 10nm and 5nm-thick shell. Magnetic measurements showed decrease in magnetisation of saturation after TiO2 drawing.
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