Preparation and characterization of p–n heterojunction photocatalyst p-CuBi2O4/n-TiO2 with high photocatalytic activity under visible and UV light irradiation

In this article, the p-type CuBi2O4 powder was prepared by the solid-state reaction method. The p–n heterojunction photocatalyst p-CuBi2O4/n-TiO2 was 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 Cr2O72− and photocatalytic oxidation of methyl orange (MO). The results showed that the photocatalytic activity of the p–n heterojunction photocatalyst p-CuBi2O4/n-TiO2 was much higher than that of TiO2 and the mixture of p-CuBi2O4–n-TiO2 without ball milling under visible and UV light irradiation. The optimal percentage of doped p-CuBi2O4 is 20 wt%. Compared with pure TiO2, 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 the photocatalytic activity of the photocatalyst was also investigated. The optimum ball milling time is 6 h. The mechanisms of influence of p-CuBi2O4 on the photocatalytic activity of p-CuBi2O4/n-TiO2 were also discussed by the p–n junction principle and the valance band theory.