利用有机溶剂水热法制备了一种新型的可见光响应纳米TiO2粉体光催化剂. 对其进行光响应特性表征, 研究发现: 固相粉末漫反射吸收谱反映了该TiO2粉体具有类似改性TiO2的可见光响应的特征; 而在纳米颗粒稀悬浮液的特定条件下, 紫外-可见吸收谱给出了该纳米TiO2粉体的类似本征TiO2的光响应特征, 观测不到其可见光响应特征; 分析表明, 该现象可能与在稀悬浮液的条件下, 声子参与的光致电子跃迁过程的退化有关.
Nanosize-TiO2 podwers with visible-light response and photocatalytic capability were synthesized by hydrothermal process with organics as solvents. Results of diffuse reflectance spectra (DRS) for solid TiO2 powders show that the visible light response properties of present nanosize-TiO2 are similar to that of modified TiO2, which have strong visible-light response in visible-light region. On the other hand, UV-Vis absorption spectra of TiO2 suspensions show that the optical properties of present nanosize-TiO2 are similar to that of intrinsic TiO2, and no obvious visible light absorption detected. Such difference in optical properties via DRS and UV-Vis
spectra for present nanosize-TiO2 is attributed to the difference status of nanosize-TiO2 existing as solid powder or dilute suspensions. Underthe conditions of extreme dilute suspensions, photon induced electron transition accompanied by phonon excitation may be degenerated while it is not the case for solid powders. For present photocatalyst with high activity under visible light
irradiation, it is necessary to combine two methods to evaluate the accurate information of the absorption edge and optical response properties.
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