Preparation of Cu-doped TiO2 via refluxing of alkoxide solution and its photocatalytic properties

Cu-doped TiO₂ was prepared by the refluxing of a mixture of copper and titanium alkoxides. The refluxing improved the Cu²⁺ dispersion in the TiO₂ and formed effective Ti–O–Cu bonds. The impurity states due to the highly dispersed Cu²⁺ were presumed to trap the electrons in the conduction band of the TiO₂ and prevent charge recombination of the electrons and holes. Consequently, the prolonged charge separation duration was suggested to enhance the photocatalytic activity of the Cu-doped TiO₂. This enhancement was confirmed by the hydroxyl radical generation and organic compound degradation. The Ti–O–Cu bonds and electronic interaction between Cu and Ti should effectively promote the electron trapping. The Cu-doped TiO₂ exhibited a visible light-induced activity due to the transition from the TiO₂ valence band to the Cu²⁺ impurity states.