Si掺杂TiO2催化剂的结构与可见光催化活性研究

采用溶胶-凝胶法制备出Si⁴⁺离子掺杂的TiO₂可见光催化剂 (TiO₂-xSi),该催化剂的可见光催化活性高于纯TiO₂和N掺杂的TiO₂(TiO₂-N).利用XRD、XPS、FT-IR和UV-Vis DRS等表征技术,研究了TiO₂-xSi催化剂的晶体结构、能带结构和表面性质.研究发现:掺入Si⁴⁺离子在TiO₂粒子表面主要形成Ti-O-Si结构,并在导带下0.2-0.6 eV区域形成表面态能级,该表面态能级的存在是催化剂产生可见光响应、实现可见光催化的根本原因.另外,讨论了Si⁴⁺离子的掺杂对金红石相和晶粒的生长抑制作用,以及催化剂的比表面积和表面羟基物种增加对可见光催化活性的影响.

Structure and Photocatalytic Activity of Silicon Doped TiO_2 Photocatalysts Under Visible Light

TiO₂ photocatalysts (TiO₂-xSi) doped by different contents of silicon were prepared by a sol-gel method. The catalysts exhibited a higher photocatalytic ability than the pure TiO₂ and N-doped TiO₂(TiO₂-N). The samples were characterized by XRD, XPS, FT-IR and UV-Vis diffuse reflectance absorption spectra. It was revealed that the doped silicon ions formed Si-O-Ti structures on the surface of TiO₂ particles. And thus, surface state energy attributed to the silicon dopant was located at 0.2-0.6 eV below the conduction band of TiO₂, which enhanced the response to the visible light and photocatalytic ability. It was discussed the suppression to the formation of rutile phase and the growth of titanium dioxide crystals because of the doped silica in TiO₂ particles and the effect of catalysts' surface area and surface species such as hydroxyl to the photocatalytic activity.