The Progress of TiO 2 Nanocrystals Doped with Rare Earth Ions

In the past decades, TiO 2 nanocrystals (NCs) have been widely studied in the fields of photoelectric devices, optical communication, and environment for their stability in aqueous solution, being nontoxic, cheapness, and so on. Among the three crystalline phases of TiO 2 , anatase TiO 2 NCs are the best crystallized phase of solar energy conversion. However, the disadvantages of high band gap energy (3.2 ev) and the long lifetime of photogenerated electrons and holes limit its photocatalytic activity severely. Therefore, TiO 2 NCs doped with metal ions is available way to inhibit the transformation from anatase to rutile. Besides, these metal ions will concentrate on the surface of TiO 2 NCs. All above can enhance the photoactivity of TiO 2 NCs. In this paper, we mainly outlined the different characterization brought about in the aspect of nanooptics and photocatalytics due to metal ions added in. Also, the paper mainly concentrated on the progress of TiO 2 NCs doped with rare earth (RE) ions.