Abstract:TiO₂/Cu₂O composites were prepared by a simple sol-gel process and chemical deposition method. The results of photocatalytic experiments under visible light irradiation demonstrate that the TiO₂/Cu₂O composite has the ability of degrading brilliant red X-3B and producing H₂ from water. The mechanism of photocatalytic reaction under visible light is proposed based on band theory and the experimental results. The electrons excited from TiO₂/Cu₂O composite under visible light are transferred from the conduction band of Cu₂O to that of TiO₂. These electrons from Cu₂O are then captured by Ti⁴⁺, which afterward are changed into Ti³⁺. These electrons located in Ti³⁺ in the conduction band of TiO₂ have a long lifetime. They can be transferred to the interface of composite and solution. In the experiment for photodegradation of brilliant red X-3B, these electrons can be captured by the O₂ adsorbed on the interface to form HO₂· or ·OH, which can oxide organic compounds. In the process of H₂ evolution, these electrons can directly combine with H⁺ to form H_2.  XPS spectra are also carried out and provide evidence for the proposed mechanism.

Key words: TiO₂/Cu₂O composite; brilliant red; Ti³⁺ ions; photocatalysis; hydrogen production; X-ray photoelectron spectrum