Study On Preparations And Properties Of CNT/Metal Oxide Composite Photocatalysts

Carbon nanotubes（CNTs） as one of the newly emerging nano-carbon materials, are ideal building blocks to construct nanocomposites, due to their unique structure and outstanding properties. Many researches have been tried to combine CNTs with inorganic materials, such as metal oxides. And the performances of these composites are superior to single component. Taking environmental issues and energy crisis of today into consideration, this thesis is devoted to incorporating effective photocatalytic materials（e.g. TiO₂, ZnO） with CNTs in mild and simple ways in order to accomplish preferable photocatalysts. Hereby, CNT/TiO₂ and CNT/Ti O2/ZnO composites have been prepared and studied in the work as well as their photocatalytic performances in degradation of organic dyes. The main research contents of this thesis are as follows:Using TiOSO4 as Ti precursor, CNT/TiO₂ binary nanocomposites were prepared by a chemical bath deposition（CBD） method at near room temperatures. Two forms of TiO₂ depositions corresponding to rutile and anatase respectively were sheathed on carbon nanotubes evenly by adjusting the precursor concentration and temperature. The loading of cluster-like rutile TiO₂ is more likely to be formed under low temperature and high acidity circumstances, while anatase coatings on the surface of CNTs could be the main form in the opposite environments. After the modification of CNTs with titania, the specific surface area and mesostructure ratio of nanotubes have been improved a lot.According to the building of CNT/anatase TiO₂ composites by CBD, the hybrids with different amounts of CNTs were prepared. Then in two given annealing conditions-- 400 ℃ calcination and 180 ℃ solvothermal treatment in methanol, two kinds of CNT/Ti O2 composite photocatalysts were obtained. Through the photocatalytic performance testing of RhB degradation, the optimal content of CNTs（6%） in the composites was made sure. The photocatalytic effect of calcinated samples are better than solvothermal samples under UV-Vis illumination, while in visible illumination the former are relatively poor.Ternary CNT/TiO₂/ZnO hybrids were prepared by an in situ two-step solution route. During the preparation process, CNTs were decorated with anatase in CBD method at first, then followed by a solvothermal method to add wurtzite ZnO nanoparticles. The experiments of RhB degradation indicate that the photocatalytic performance of the CNT/TiO₂/ZnO composite photocatalysts is superior to their counterparts（CNT/ZnO and TiO₂/ZnO and ZnO）, especially under UV-Vis light. The results show that the synergistic effects among multiple components are of great significance in building efficient composite catalysts.