Synthesis of Highly Luminescent and Anion‐Exchangeable Cerium‐Doped Layered Yttrium Hydroxides for Sensing and Photofunctional Applications

The discovery of new lanthanide properties in layered rare‐earth hydroxides is tremendously important to developing novel materials with the advantages of both lanthanides and layered hydroxides. Herein, a polyethylenimine‐assisted hydrothermal route for preparing Ce‐doped layered yttrium hydroxide nanoplates (LYH:Ce NPs) is established, in which the Ce doping provides simultaneous control of the size and fluorescent properties. Typically, 10% Ce doping tailors the average particle size from 680 to 196 nm and induces bright blue luminescence with a quantum efficiency of over 10.0%. Owing to the much more efficient f–d Ce³⁺ transition, the LYH:Ce NPs show three orders of magnitude stronger photoluminescence than LYH:Eu and LYH:Tb NPs, and exhibit the properties required to fabricate switched “on/off” optical sensors by controlling the Ce³⁺ ? Ce⁴⁺ redox couple. Furthermore, by combining the merits of the luminescence of Ce³⁺ dopants and anion‐exchange ability of an LYH host, the LYH:Ce NPs exhibit the properties necessary for photofunctional materials for photosensitized singlet oxygen production.