Preparation and characterization of Cu2O–TiO2: Efficient photocatalytic degradation of methylene blue

A series of copper-deposited titania were prepared by photoreduction method under irradiation with a 125-W high-pressure mercury lamp. From XPS and AES results, the deposited-copper formed Ti–O–Cu bond on the surface of TiO2, and the Cu species on the surface of copper-deposited TiO2 can be identified as Cu(I). The photocatalytic degradation activity of methylene blue for the Cu2O–TiO2 series increased with increasing Cu2O-deposited content, and then decreased. The highest photocatalytic degradation activity of methylene blue was obtained for 0.16% Cu2O–TiO2. When copper-deposited content reached to 0.32%, the photocatalytic activity was lower than that of pure TiO2. It is shown that Cu2O on the surface of TiO2 can trap electrons from the TiO2 conduction band, and the electrons trapped on the Cu2O–TiO2 site are subsequently transferred to the surrounding adsorbed O2, thereby avoiding electron–hole recombination, and enhancing the photocatalytic activity. Excess copper loading may screen the photocatalyst from the UV source, so the photocatalytic activity diminishes with increasing Cu2O.