Study on the Photocatalytic Activity of <I>p</I>–<I>n</I> Junction Photocatalyst Cu<SUB>2</SUB>O/TiO<SUB>2</SUB>

p-n junction photocatalyst Cu2O/TiO2 was prepared by ball milling through doping Cu2O into TiO2 and using H2O solution as disperser. The p-n junction photocatalyst Cu2O/TiO2 was characterized by UV-Vis diffuse reflection spectrum, Scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr2O7(2-) and photocatalytic oxidation of methyl orange (MO), respectively. The results showed that, for the photocatalytic reduction of Cr2O7(2-), the optimum percentage of doped-Cu2O is 1.0% (weight percentage). The photoreduction activity of the p-n junction Cu2O/TiO2 is much higher than that of TiO2 on the photocatalytic reduction of Cr2O7(2-). However, the photooxidation activity of the p-n junction photocatalyst Cu2O/TiO2 is much lower than that of TiO2 on the photocatalytic oxidation of methyl orange (MO). Namely, the p-n junction photocatalyst Cu2O/TiO2 has higher photocatalytic reduction activity, but lower photocatalytic oxidation activity. Cu2O and TiO2 were coupled highly, forming the p-n junction Cu2O/TiO2 photocatalyst. The photocatalytic activity of the p-n junction Cu2O/TiO2 was discussed by the p-n junction principle. Effect of ball milling time on the photocatalytic activity of p-n junction photocatalyst Cu2O/TiO2 was also investigated.