Preparation And Photocatalytic Properties Of Oxide Semiconductor Nanomaterials

With the development of nanotechnology, semiconductor nanomaterials have attracted a lot of attentions because of unique optical, electrical and magnetic properties. Currently, semiconductor nanomaterials have been widely used in sensors, dye-sensitized solar cells, photocatalysis and many other areas. Photocatalytic technology as a clean, simple and efficient one has been widely used in the photocatalytic degradation of organics, water splitting for hydrogen, sterilization, self-cleaning glass and other fields. However, due to the natural properties, the photocatalytic activity of photocatalyst has been limited by some factors: narrow range of light response, low efficiency of light utilization, high recombination rate of photogeneration carriers and so on. Therefore, it is very meaningful to study some possible ways to improve the photocatalytic activity of photocatalyst.Considering the natural properties of semiconductor photocatalyst, we developed three ways to improve the photocatalytic activity of semiconductor photocatalysts in this paper. At first, we prepared porous ZnO foams with a simple combustion. It can improve the surface area and utilization ratio of the light. Secondly, the light response range of porous ZnO foams and separation of photogeneration carriers can be improved by modifying CQDs on the surface of the porous ZnO foams. Finally, TiO2/Cu₂ O core-shell nanowires are prepared to enhance the light response range and separation of photogeneration carriers. Therefore, some important results have obtained as the following.?1? Porous ZnO foams are successfully prepared by combustion. It can be seen that the porous, foam structure is consisted of aggregated ZnO nanoparticles with good crystallinity. A lot of hierarchical pores from microscale to nanoscale can be found. The as-prepared ZnO foams as photocatalyst are used to degrade Rhodamine B. The results show that the ZnO foams have good photocatalytic activity. The reason is that the ZnO foams have high specific surface area and surface activity. So it can adsorb more Rhodamine B molecules. On the other hand, the porous, foam structure has good light trapping effect, which improves the utilization of light. So the photocatalytic activity of the material can be improved. In addition, the combustion has a lot of advantages compared to other methods, such as the simple procedure, low experimental requirement. Therefore, the combustion can provide a new route for large-scale industrial application of photocatalyst.?2? A simple solution method is used to modify CQDs on the surface of porous ZnO foams. The porous, foam structure can be found. There is no obvious change about the structure and morphology of ZnO foams. The nanocomposite exhibits a certain amount of absorption for visible light according to the UV-visible absorption spectrum. The as-prepared nanocomposite as photocatalyst is used to degrade Rhodamine B. It can been found that the nanocomposite has excellent photocatalytic activity under UV and visible light irradiation compared with pure ZnO foams. Because of the photo-induced electron transfer property and up-converted photoluminescence behavior, the light response range of nanocomposite and separation of photogeneration carriers can been improved. So the photocatalytic activity has been improved.?3? A simple solution aging process is utilized to prepare the Cu₂ O layer on the surface of electrospun TiO2 nanofibers to form heterojunction structure. We found that the diameter of TiO2/Cu₂ O core-shell nanofibers is about 100 nm. The length can reach to several micrometers. The core-shell nanofibers has a good crystallinity. The core-shell nanofibers exhibit a certain amount of absorption for visible light according to the UV-visible absorption spectrum. As photocatalyst to degrade Rhodamine B, the core-shell nanofibers has excellent photocatalytic activity under UV and visible light irradiation compared with pure TiO2 nanofibers. The heterojunction can improve the light response range of TiO2/Cu₂ O nanofibers and separation of photogeneration carriers. Therefore, the photocatalytic activity of TiO2/Cu₂ O nanofibers has been improved.