The metallic platinum clusters in size of 3 nm were photocatalytically deposited on anatase (7 nm) or mesoporous TiO₂ in the presence of citric acid as a double-functional agent (a hole scavenger and a dispersant to keep Pt clusters from agglomeration). The particle size of the deposited platinum was uniform and in the range of 3～4 nm, and the surface of majority of TiO₂ nanocrystals was deposited with an island of Pt cluster. Both XPS and ED results identified that the deposited Pt consisted of metallic atoms. The Pt/TiO₂ showed a significantly enhanced photocatalytic activity using the degradation of phenol as a model reaction. The Pt/TiO₂ was subjected to nitridation in the flowing NH₃ at 550 ℃, and Pt-loaded TiO₂-_xN_x nanocrystals were obtained. The particle size of Pt clusters was preserved and Pt clusters were not sintered at this temperature.

Key words: titania, photocatalytic deposition, photocatalyst, platinum, visible light driven photocatalysis