Preparation and activity evaluation of p–n junction photocatalyst NiO/TiO 2

Abstract

p–n Junction photocatalyst NiO/TiO 2 was prepared by sol–gel method using Ni(NO 3) 2·6H 2O and tetrabutyl titanate [Ti(OC 4H 9) 4] as the raw materials. The p–n junction photocatalyst NiO/TiO 2 was characterized by UV–vis diffuse reflection spectrum, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr 2O 7 2− and photocatalytic oxidation of rhodamine B. The results show that, for photocatalytic reduction of Cr 2O 7 2−, the optimum percentage of doped-NiO is 0.5% (mole ratio of Ni/Ti). The photocatalytic activity of the p–n junction NiO/TiO 2 is much higher than that of TiO 2 on the photocatalytic reduction of Cr 2O 7 2−. However, the photocatalytic activity of the p–n junction photocatalyst NiO/TiO 2 is much lower than that of TiO 2 on the photocatalytic oxidation of rhodamine B. Namely, the p–n junction photocatalyst NiO/TiO 2 has higher photocatalytic reduction activity, but lower photocatalytic oxidation activity. Effects of heat treatment on the photocatalytic activity of p–n junction photocatalyst NiO/TiO 2 were investigated. The mechanisms of influence on the photocatalytic activity were also discussed by the p–n junction principle.