| In order to study the effect of Titanium dioxide (TiO2) with different morphologies on the photocatalytic activity of organic pollutants, and to solve the problem of the narrow area of TiO2 optical radiation and the puzzle of photo-generated electron and hole recombination easily, a series of tests have been carried out to improve degradation efficiency and speed of pollutants. Firstly, TiO2 nanocup morphology with a large specific surface was prepared by situ growth method which is combined with the principles of chemical etching. In addition, (001)-TiO2 and (100)-TiO2 nano sheets are achieved in simple hydrothermal way. On this basis, xPt/TiO2 (x is mass ratio of Pt and TiO2 in 0～3%.) nanocomposites and three-dimensional graphene/TiO2 composite bulk material with three different TiO2 morphologies (nanocup, (001) nanosheet, (100) nanosheet) were prepared to meet the above purposes. Secondly, phase compositions of the microstructure are measured by X-ray diffraction patterns (XRD). The formation of nanocup, (001) nanosheet, (100) nanosheet of TiO2 and the presence of Pt nanoparticles attached on TiO2 nanostructure was confirmed by scanning electron microscopy and transmission electron microscopy results. Besides, Test analysis (BET) was applied for obtaining specific surface area of the solid particles. Finally, UV-visible spectrophotometer was used to measure removal ratio of organic dye Rhodamine B to represent the degradation activity of samples.The results are showed as follow:(1) All TiO2 samples are pure anatase indicated by X ray diffraction. Almost all the particles maintain the well-defined cup-like shape with uniform diameter sizes. The sizes of nano cup and opening of particle are mainly distributed in 150±5nm, 100nm, correspondingly. (001)-TiO2 consisted of a rectangular outline whose side-length are 60* 40nm, and the length, width of (100)-TiO2 nanosheets are falled in 100-200nm,15～25nm, respectively. Furthermore, specific surface of samples are in variety that nanocup is 99m2/g twice as sheets. As for the photodegradation features, nanocup reaches the best efficiency 99.94%. In summary, the order of photocatalytic activity is three cup> (001)-TiO2> (100)-TiO2.(2) With respect to Pt/TiO2 composite, only 3%Pt/TiO2 is observed the corresponding peaks of Pt due to its content. There are lattice distortions and grain size decreases (about 60nm) during preparation of Pt/nanocup. About 2-5nm Pt particles are distributed in the titanium dioxide surface; but 2% Pt/TiO2 still showed the highest degradation rate, 3%Pt/TiO2 worse, and 1%Pt/TiO2the worst.(3) Among the three-dimensional graphene (GR)/TiO2 bulks, a lot of micron pores are realized on surface. Besides, slightly decreases occur to diameter of nano cup, but the opening size holds are unchanged. GR which is attached to (001) nanosheets showsthe highest reducibility, at the same time broken phenomenons which exist in (001)-TiO2 result in deformation, whose length turns into 20～40nm and only 1/3～1/2 of the original width. Photodegration data reveal that removal rate of Rh.B is about 64%with GR/(001)-TiO2 during 0～1h, while the rates display only 21%,15% with GR/nanocup and GR/(100)-TiO2, correspondingly; then within 1～2h, the decomposition rate of GR/(001)-TiO2 composite bulk slows down, while the rest of samples accelerated the reaction rate, conversely. The mechanical strength of GR/(001)-TiO2 three-dimensional bulks takes the first place, followed by GR/nano cup, GR/(100)-TiO2 at last. |
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