| Summary: | 碩士 === 國立清華大學 === 物理學系 === 105 === Recently, photocatalytic materials have attracted special research interest due to heightened awareness of the importance of environmental protection. Among such materials, many research works have been focused on titanium dioxide for its wide and versatile catalytic applications. However, the low activity of these catalysts in applications using visible light has limited their further development. In this thesis, we investigated the effect of (Co,Zr) co-dopeing on the structures and band gap width of the doped TiO2 host. Samples were synthesized by a sol-gel method followed by thermal annealing at 500oC. The extended x-ray absorption fine structure (EXAFS) data show that both cobalt and zirconium substitute for Ti in the TiO2 host. The existence of metal oxides in the samples was also excluded by our data. Most importantly, the band gap of TiO2 decreases with increasing Zr concentration. The observed dependence of band gap on Zr concentration indicates a rather unique mechanism governing the band gap variation in these co-doped oxides.
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