State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, P. O. Box 110, Dalian 116023, China.
Phys Chem Chem Phys. 2010 Jul 14;12(26):7083-90. doi: 10.1039/b925277k. Epub 2010 May 13.
Anatase and rutile TiO(2) were investigated with photoluminescence techniques under the weak excitation condition, where trap states play a vital role in carrier dynamics. The visible emission of anatase and near-infrared (NIR) emission of rutile both exhibit extremely long lifetimes up to milliseconds. The decay processes can be well described by the power-law decay which corresponds to the trapping-detrapping effect. These results indicate that the luminescence processes in both anatase and rutile TiO(2) have a close relationship with trap states. The visible emission band was assigned to the donor-acceptor recombination. Oxygen vacancies and hydroxyl groups mainly serve as the donor and acceptor sites, respectively. The NIR luminescence is originated from the recombination of trapped electrons with free holes, while the trapped electrons were formed through two paths, direct trapping or trap-to-trap hopping. The trap states in anatase and rutile TiO(2) may largely influence the photocatalysis process of TiO(2) and determine the photocatalytic activity under stationary illumination.
锐钛矿和金红石 TiO(2) 在弱激发条件下通过光致发光技术进行了研究，其中陷阱态在载流子动力学中起着至关重要的作用。锐钛矿的可见发射和金红石的近红外 (NIR) 发射都表现出极其长的寿命，可达毫秒级。衰减过程可以很好地用幂律衰减来描述，这对应于俘获-脱陷效应。这些结果表明，锐钛矿和金红石 TiO(2)中的发光过程与陷阱态密切相关。可见发射带归因于施主-受主复合。氧空位和羟基主要分别作为施主和受主位点。NIR 发光源于被捕获的电子与自由空穴的复合，而被捕获的电子通过两条路径形成，直接捕获或陷阱间跳跃。锐钛矿和金红石 TiO(2)中的陷阱态可能会极大地影响 TiO(2)的光催化过程，并决定在静态光照下的光催化活性。
