Preparation And Modification Of Mesoporous Titanium Dioxide Nanomaterials

With the advance of society and the development of economy, the problem of environmental pollution has become more and more serious. The management and control of environmental pollution has become a major problem for humanity to be solved urgently. For photochemical catalysis materials, the separated electron and hole under light can effectively catalyze the organic pollutants into water and carbon dioxide and other small molecule compounds. Due to its non-toxic, acid and alkali stability, biological compatibility, titanium dioxide(TiO2) nanomaterials reached a lot of attention. As a new treatment technology of water pollution, although much achievementhave been doneat present, there are still a lot of problems need to be solved, such as its wide band gap, it can be only respond to the UV light, and its easily recombineded electron and holes.To solve the aboved problems, by means of preparing mesoporous titanium dioxide nanomaterialand modifying the titanium dioxide nanomaterial, we improvedits photocatalytic activity. The specific research contents three parts:1. The mesoporous single crystal titanium dioxide was prepared by hydrothermal method with tetrabutyl titanate as titanium source and silica as template. After that, different amount of Ag was deposited on the prepared TiO2 by photodeposition method. In a certain range, with the increased Ag amount, the photocatalytic performance of mesoporous Ti O2 will be enhanced. When its amount is 5%, the catalytic activity is the best. This is because the noble metal Ag can produce plasma resonance effect, inhibiting the recombination of electron and hole, thus enhance the photocatalytic performance of mesoporous Ti O2. When the amount of Ag higher than 5%, the photocatalytic performance of mesoporous TiO2 will decrease with the increase of Ag content. That is because Ag nanoparticles will be aggregated in deposition, blocking the TiO2 channel, and reduce its photocatalytic activity.2. Doping tungsten irons into mesoporous TiO2 by hydrothermal method. We found that the doping could enhanced the specific surface area of porous TiO2, thus increase its adsorptive capacity of pollutant. At the same time, doping could also make a widened absorption wavelengthcoverage, which reflects a more efficient use of resources. In the conditions of simulated sunlight, the photocatalytic performance of W6+ doped mesoporous titanium dioxide is better than that of titanium dioxide. It may because the doping of W6+ can improve the separation efficiency ofelectron and holesof mesoporous TiO2, which can improve the photocatalytic activity.3. Based on commercial titanium dioxide P25, W-TiO2 was prepared by hydrothermal method, and Au/W-TiO2 was prepared by the method of optical deposition. Due to the plasmon resonance effect of Au nanoparticle, Au/TiO2 and Au/W-Ti O2 have a strong absorption band in the visible region, indicating that the deposition of noble metal Au expand the response of TiO2 to visible light region. Compared with undoped TiO2, the doping of tungsten into TiO2 leads to the efficient quenching of the photoluminescence, which may be attributed to the photoexcited electrons in the conduction band of TiO2 can be accepted byW6+ in the solid solution, so as to inhibits the recombination of electron and hole. In the photocatalytic activity test, when W-TiO2 was modified by noble metal Au nanoparticles and its photocatalytic degradation rate was significantly higher than that of TiO2, W-TiO2 and Au / TiO2, which is mainly attributed to the on the synergetic effect of W6+ doping and deposition of Au nanoparticles.