Preparation, Characterization And Activity Evaluation Of P-n Junction Photocatalyst P-zno-tio_2

摘要

In this paper, p-type ZnO powder was prepared by decomposition of zinc nitrate at 350℃ for 1 h. p-n junction photocatalyst p-ZnO/TiO_2 was prepared by ball milling of TiO_2 in H_2O solution doped with p-ZnO. The p-n junction photocatalyst p-ZnO/TiO_2 was characterized by UV-vis diffuse reflection spectrum, scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and the fluorescence emission spectra. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr_2O_7~(2-) and photocatalytic oxidation of methyl orange (MO). The results showed that the photocatalytic activity of the p-n junction p-ZnO/TiO_2 is much higher than that of TiO_2 on the photocatalytic reduction of Cr_2O_~(-2) . However, the photocatalytic activity of the photocatalyst is much lower than that of TiO_2 on the photocatalytic oxidation of methyl orange. Namely, the p-n junction photocatalyst p-ZnO/TiO_2 has higher photocatalytic reduction activity, but lower photocatalytic oxidation activity. When the amounts of doped p-ZnO are 0.0 and 2.0 wt.%, illumination for 20 min, the photoreduction efficiencies are 15.7 and 42.8%, and the photooxidation efficiencies are 68.1 and 26.1%, respectively. Effect of ball milling time on the photocatalytic activity of the photocatalyst was also investigated. The mechanisms of influence on the photocatalytic activity were also discussed by the p-n junction principle.