Preparation And Properties Of Titanium Dioxide-Based Composite Materials

In recent years, TiO2has been widely employed for its high photocatalytic activity, good stability,non-toxicity，cheapness and abundance. However, TiO2can only be excited by ultraviolet light for itswide band gap. Via various approaches to modify TiO2, the optical response of which can be extendedto visible light region, which greatly expands the widespread applications of TiO2photocatalytictechnology. In the thesis, in order to have an enhancement in photodegradation efficience undervisible light illumination, a series of TiO2-based nanocomposite photocatalysts were prepared. Thecrystal structure and the morphology of the resultant samples were studied by XRD and SEM, thelight absorption performance was investigated by UV-Vis spectroscopy. Furthermore, thephotocatalytic capacity and the mechanism of the TiO2-based nanocomposite photocatalysts were alsostudied.First of all, TiO2nanotubes were prepared by anodic oxidation method, the Cu2O/TiO2heterostructure nanocomposite photocatalysts were prepared by electrochemical deposition methodwith of TiO2nanotube arrays as the basement. Cu2O/TiO2nanocomposite photocatalysts has a bettervisible light response and exhibited enhanced photocatalytic activity than the bare TiO2nanotubes inthe photocatalytic experiment that90%AO was degraded using the1.0C Cu2O/TiO2nanocompositephotocatalysts and only20%AO was decolorized by the bare TiO2nanotubes after2h of visible lightirradiation. Furthermore, it also exhibited high photocatalytic activity in conversion of CO2tomethanol. After6h irradiation, the maximum concentration of methanol reduced by CO2is55.15uM/100mL and the maximum CO2conversion efficiency is about0.48%. The maximum photonicefficiency of CO2photoreduction can be computed to be about1.731%. The ultra enhancedphotocatalytic activity could be attributed to the formation of Cu2O/TiO2heterostructures with higherseparation effciency of photo-generated electrons and holes. Then TiO2was reacted with grapheneoxide by hydrothermal synthesis to form TiO2/Graphene nanocomposite. Ag3PO4nanoparticals werethen loaded on the TiO2/Graphene nanocomposite to get the Ag3PO4/TiO2/graphene nanocomposite.The enhanced photocatalytic activity was due to the formation of Ag3PO4/TiO2heterostructures whichcould broaden the absorption wavelength and restrain the recombination of photo-generated electronsand holes. The Pt@SiO2@TiO2composite was also prepared by a simple method. In thephotocatalytic experiment40%RhB can be degraded by Pt@SiO2@TiO2nanocompositephotocatalysts and25%RhB was decolorized by Pt@TiO2nanocomposite photocatalysts, only3%RhB degraded in2h by the bare TiO2of visible light irradiation. Experimental results show that the Pt@SiO2@TiO2composite structure has a better photocatalytic performance than the TiO2andPt@TiO2. This can be due to the the existence of the SiO2layer which can restrain and reduce theelectronic transfer caused by localized plasmon resonance and the energy dissipation in TiO2causedby FRET efficiently. The localized surface plasmon resonance (LSPR) can also be strengthen by theSiO2layer and result in a better photocatalytic performance than Pt@TiO2composite structure.The various of TiO2-based composite photocatalyst with a better visible light response wereprepared, which also exhibited stronger light absorption and higher photocatalytic activity. These newphotocatalyst can effectively restrain the recombination of carriers and improve the utilization of solarenergy, thus having a good application prospect in the areas such as industrial pollution control andphotoelectric catalysis.