| Semiconductor mediated photocatalysts has a broad development prospects in solar energy application and environmental applications. Among numerous semiconductors, Ti O2 nanostructures have attracted growing interests because of Non-toxic, low price, light resistance and stable chemical properties. But for the pure nano-Ti O2, the disadvantage is the short lifetime of excited electron-hole pairs, which reduces the photocatalytic performance and limits the applicability severely. In order to improve the photocatalytic performance of Ti O2, the modification of Ti O2 nanostructure become hot research topic in the field of photocatalysts. Rare earth elements doping has long been known as one of the most effective approaches to improve its photocatalytic performance. Rare earth doped Ti O2 create more abundant oxygen vacancies and surface defects in Ti O2, which accelerates the separation of photogenerated electron-hole pairs and enhances the photocatalytic performance. PL spectra is always used as an effective method to study optical properties and electronic structure of semiconductor, which can obtain the information of photogenerated charge carrier for migrate, capture, compound and etc. So it is significant to study of PL spectra and to prepared high photocatalytic performance of Ti O2 nanostructures.Different calcination temperatures and Gd, Y-doped Ti O2 nanopowders were prepared by sol-gel methed, which was used as precursor subsequently. The corresponding Ti O2 nanotubes were synthesized by hydrothermal method under microwave irradiation, and characterized by Field emission scanning electron microscopy(FESEM), Field emission transmission electron microscopy(FETEM), X-ray diffraction(XRD) and PL spectra. The influence on structure, morphology, and crystal form of microwave treatment by different temperature Ti O2 nano-powder were study. And the effect of Gd, Y content on morphology, crystallinity and photoluminescence of Ti O2 nanopowders and nanotubes were investigated.The influence of microwave treatment of different temperature on the structure, morphology, and crystal form of Ti O2 nanopowder was investigated, which provides reasonable experiment scheme for the research on the structure and properties of Gd/Ydoped Ti O2 nanotubes. The results showed that the calcination temperature increased grain size of Ti O2 nano-powder. The calcination temperature has little influence on Ti O2 nanotube morphology by microwave treatment. Moreover, The Ti O2 calcined by 600 ℃ and 700 ℃ has crystal transform anatase to rutile by microwave hydrothermal synthes is method. While the 500 ℃ calcination of Ti O2 crystal form was unchanged.The size of Ti O2 nanopowder was attributed to content of the Gd/Y. The diameter of Ti O2 nanopowders decreased with the increase of the Gd, Y dopant content, the diameter decreased to about 10 nm and 9.3 nm respectively when Gd, Y dopant increased to 2%. While Gd/Y doping has little influence on the morphology of Ti O2 nanotubes. Moreover, the crystallinity enhanced with increased content of Gd, Y doping. And the appropriate Gd, Y dopant can maintain Ti O2 nanotubes crystallinity with an appropriate content. The Mechanism needs to be further reseached.Because the rare earth Gd/Y entranced into the lattices of Ti O2, it can create abundant oxygen vacancies and change concentration of surface defects. Result in that the photoluminescence properties firstly increased and then decreased with the increase of Gd, Y content. It obtained the largest FS intensity When Ti O2 nanopowder doped with 0.5% contents of Gd, and when the content were 0.2% and 0.5%, the Ti O2 nanotubes got the largest FS intensity. For Ti O2 nanometer powder doped with rare earth Y, the FS intensity obtained the largest degree when the content is 0.5%, and when content was 1%, the Ti O2 nanotubes obtained the largest FS intensity.It significantly enhanced the photocatalytic activity of Gd/Y-doped Ti O2, which was attributed to a combination of factors like creation of defect level,and enhanced lifetime of photogenerated charge carriers. The photocatalytic became higher activity of Ti O2 nanopowder with doping 0.5% Gd. Morover, the optimized concentration of Gd in Ti O2 nanotube was 1%. Compared to other Ti O2 nanopowder sample, doping 0.5% Y, the photocatalytic activity was the highest, the optimized concentration of Y in Ti O2 nanotube was 1%. Compared with the pure Ti O2 nanopowder, photocatalytic activity of Gd/Ydoped one increased by 44.7% and 40% respectively. Compared with the pure Ti O2 nanotube, photocatalytic activity of Gd/Y-doped one increased by 71% and 27.7% respectively.The FS intensity and photocatalytic activity has trends consistency visibly by doping Gd, Y for Ti O2 nanopowder. But the optimal doping contents are not consistent. The photoluminescence properties can be used for rapid assessment of photocatalytic activity broadly with Gd/Y-doped Ti O2. |
PDF Full Text Request