Preparation And Characterization Of TiO₂/Graphene Magnetic Composition

Photocatalyst can use light to degrade the environmental pollutants, not only play the role of environmental governance, but also can save energy. Among them the traditional TiO₂ photocatalysis material, because of its low price, non-toxic, the chemical stability, it deserve the researchers's favor. Pure TiO₂ can only absorb ultraviolet light, and cannot use visible light, which make its application of catalytic degradation is restricted. Researchers study the modification methods, and have obtained some achievements, but there also need to further perfect, to make it not only the outstanding performance, but also more practical application value.Graphene is two-dimensional crystal material, it has many unique properties. With its high specific surface area and good conductive, TiO₂ combines with graphene, it is expected to significantly improve the activity of photocatalyst. Therefore, by the improved Hummers method, the graphene oxide was prepared, and joined it into TiO₂ precursor, through hydrolysis reaction, TiO₂ combined with grapheme oxide, and then after reduction reaction, TiO₂ and graphene combination materials were got. The TiO₂ powder has relatively high photocatalysis activity, but the recycling is difficulty, CoFe₂O₄ magnetic particles were prepared by the precipitated method, and combined with TiO₂ by sol-gel method. Using its property of magnetism, the ecycle of photocatalyst is more efficient and convenient. In order to prepare the catalyst with high photocatalytic activity and easily recycled. CoFe₂O₄, graphene and TiO₂ compound together by hydrolysis method, which is a new photocatalyst with better performance. All sorts of composite materials were characterized by the infrared spectrum, X-ray diffraction, uv-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope, etc. The crystal style, bonding on surface and surface morphology etc have been deeply studied, and the influence of experimental conditions on catalytic active and its structure is discussed, then the best preparation conditions were determined.The GO has many polarity oxygen groups, which promote its solubility significantly. The graphene was got by reductive action, and it has slice layer structure, whose thickness is 0.649 nm. GO and RGO have strong absorption in visible area.The combinations with different quality ratio of TiO₂/GO and TiO₂/RGO were got by the modified Hydrolysis method, and the TiO₂ in the combinations are anatase. The TiO₂ particles were deposited on the slice layer of GO and RGO. The research shows that TiO₂ particles combined with the groups of C-OH and C=O in the nucleation process, and the TiO₂ activity of integration with COOH is very low. The combinations have strong absorption in both UV-light area and visible area. Under visible light, the composite with the quality ratio 1:0.15 of TiO₂ to GO and RGO has the higher photocatalytic activity than the others, the degradation rate reached 99% and 97.4% respectively in 2h, it is far higher than the pure TiO₂ 36.8%. The composite also has good repeat performance.The TiO₂/CoFe₂O₄ composites with different molar ratio were prepared by Sol-gel method, through different temperature calcination, the TiO₂ in the composites remains the original style, and CoFe₂O₄ is spinel crystal. The composites all have magnetism, and with the increasing of the content of CoFe₂O₄, the magnetic property is enhanced. Samples showed irregular surface, the CoFe₂O₄ magnetic particles coated with TiO₂ on the surface. The combinations have strong absorption in both UV-light area and visible area. Through the visible degradation experiment, considering the magnetism and catalytic activity comprehensively, the composite with the molar ratio 1:0.15 of TiO₂ to CoFe₂O₄ and calcinated at 450℃has good performance of photocatalysic active and actual use.The different mass ratio of TiO₂/CoFe₂O₄/RGO composites were prepared, which all have strong magnetism, thus it is achieved the purpose that using magnetism make the recycle of catalyst more convenient. TiO₂ in the composites is anatase, and CoFe₂O₄ is spinel, both of the granules deposited on the slice layer of RGO, TiO₂ wrapped on CoFe₂O₄ particle surface, and with the increasing of the content of CoFe₂O₄, there are certain reunion phenomenon. Composites have strong absorption within the scope of whole spectrum. The experiment of methyl orange solution degradation under visible light was carried on, the composite with the mass ratio 0.75:0.2:0.15 of TiO₂, CoFe₂O₄ and RGO has the best performance of the photocatalytic degradation rate, which is 2.3 times of pure TiO₂.