Synthesis And Photocatalytic Of Composite Nanometer Titanium Dioxide

Titanium dioxide has been investigated extensively in the field of environmental protection due to its low cost, non-toxicity, high stability and excellent efficiency in degradating organic pollutants of waste water.However, the photocatalytic efficiency of TiO2 was limited owing to the large band gap and high recombination rate of the photogenerated electron/hole pairs.To improve the photocatalytic activity of TiO2, efforts should be made for overcome these defects.Carbon nanotubes (CNTs) could be used to improve the photocatalytic activity of TiO2 because of the unique structure and the outstanding electron transport properties.But the application of CNTs has been severely limited for its poor dispersion. As a kind of inorganic dispersants,phosphotungstic acid (HPW) could be uesd to improve the dispersibility of CNTs.And HPW can improve the photocatalytic activity of TiO2 nanoparticles due to its intrinsic electronic attribute.In this thesis,HPW and carbon nanotubes co-doped TiO2 nanoparticles with the excellent photocatalytic activity was prepared.In view of that TiO2 nanotubes have been found to give some advantages over TiO2 nanoparticles due to their novel properties, such as unique shape and large specific surface area.In this thesis,HPW doped TiO2 nanotubes with the high thermal stability and excellent photocatalytic activity was prepared.The chief contents of this thesis are listed below:1.Phosphotungstic acid doped TiO2 nanoparticles was prepared by sol-gel method.The samples were characterized by XRD,BET,SEM,FT-IR and UV-vis diffuse reflectance spectroscopy.The band gap values of the catalysts were calculated from the UV-Vis spectra using the Kubelka-Munk function. And the photocatalysis of samples was evaluated with methyl blue degradation.Effects of the different content of HPW on composites for enhanced activities was discussed.After two hours, the degradation rate of HPW(10wt%)/TiO2 was 96.1%,had about a 9 percent higher than pure TiO22.Phosphotungstic acid and carbon nanotubes co-doped TiO2 nanoparticles was prepared by sol-gel method.The samples were characterized by XRD,BET,TEM, FT-IR and UV-vis diffuse reflectance spectroscopy.The band gap values of the catalysts were calculated from the UV-Vis spectra using the Kubelka-Munk function. And the photocatalysis of samples was evaluated with methyl blue degradation.The role of phosphotungstic acid and carbon nanotubes in composites for enhanced activities was discussed.The degradation rate of HPW(5wt%)/CNTs(5wt%)/TiO2 was 96.1% after an hour,had about a 28 percent higher than pure TiO23.Phosphotungstic acid doped TiO2 nanotubes was prepared by the combination of hydrothermal treatment with a simple immersion process. The samples were characterized by XRD,BET,TEM,and UV-vis diffuse reflectance spectroscopy.The band gap values of the catalysts were calculated from the UV-Vis spectra using the Kubelka-Munk function.And the photocatalysis of samples was evaluated with methyl bluedegradation. The influences of various calcinations temperatures on the phase crystal form and microstructure of TNTs were described.HPW-doped TiO2 nanotubes exhibited better thermal stability compare with pure TiO2 nanotubes after calcination.The removal efficiency of MB in water of samples was attributed to the combined effect of the rapid achieved of adsorption-desorption equilibrium and the effect of photocatalytic degradation.