Preparation and characterization of p-n heterojunction photocatalyst p-CuBi_2O_4-TiO_2 with high photocatalytic activity under visible and UV light irradiation

摘要

In this article, the p-type CuBi_2O_4 powder was prepared by the solid-state reaction method. The p-n heterojunction photocatalyst p-CuBi_2O_4-TiO_2was prepared by ball milling. The photocatalyst was characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM), and photoluminescence emission spectra. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr _2O7~(2-)and photocatalytic oxidation of methyl orange (MO). The results showed that the photocatalytic activity of the p-n heterojunction photocatalystp-CuBi_2O_4-TiO_2 was much higher than that of TiO_2 and the mixture of p-CuBi_2_(O-4)-n-TiO_2 without ball milling under visible and UV light irradiation. The optimal percentage of doped p-CuBi _2O_4is 20 wt%. Compared with pure TiO_2, the photoabsorption wavelength range of the photocatalyst is extended greatly toward visible light and improves the utilization of the total spectrum. The effect of ball milling time on thephotocatalytic activity of the photocatalyst was also investigated. The optimum ball milling time is 6 h. The mechanisms of influence of p-CuBi_2O_4 on the photocatalytic activity of p-CuBi _2O_4-TiO_2 were also discussed by the p-n junction principle and the valance band theory.