A series of Pt/RE/TiO₂ photocatalysts were prepared by sol-gel impregnation and photodepositon process, and characterized by means of X-ray diffraction and electrochemistry. As a model reaction, photocatalytic hydrogen generation from water using formaldehyde as electron donor was investigated. It has been found that the activities of all rare earth doped TiO₂ samples have been increased compared to those of pure TiO₂, and the order was La/TiO₂＞Sm/TiO₂＞Eu/TiO₂＞Dy/TiO₂＞Er/TiO₂. It was shown that the transformation from anatase to rutile was prevented, which could enhance the activities of the photocatalysts. The data of lattice distortion implied that Ti^4＋could enter (anti-dope) into rare earth oxide that existed on the surface of titanium dioxide. The data of electrochemistry experiment showed that the flat-band potential of conduction of RE/TiO₂ has been shifted negatively. The lattice distortion raised the Fermi level, which caused flat-band potential of the conduction of TiO₂ to shift negatively. As a result, the photoinduced electrons of the conduction band had stronger reductive capability and the photocatalytic activity of hydrogen generation was improved.

Key words: titanium dioxide, photocatalysis, rare earth, lattice distortion, flat-band potential, hydrogen generation