Synthesis of BiOCl/TiO 2 heterostructure composites and their enhanced photocatalytic activity

The BiOCl/TiO2 heterojunction photocatalysts with varying weight ratio were synthesized through a modified sol-gel method. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and UV–visible diffused reflectance spectroscopy (UV–vis DRS). The photocatalytic activities of the catalysts were evaluated using rhodamine B, tetracycline hydrochloride and formaldehyde as the target pollutants. The characterization results revealed that the BiOCl/TiO2 composite photocatalyst exhibited the higher visible-light-responsive photocatalytic performance than pure BiOCl and TiO2. The results showed that the BiOCl/TiO2 with mass ratio of 70% exhibited the optimal photocatalytic performance. The rate constant of it for rhodamine B degradation is around 11 times as high as that of the pure BiOCl and 46 times than pure TiO2. The enhanced photoactivity should be attributed to the formation of heterojunction between BiOCl and TiO2. The BiOCl/TiO2 hybrid photocatalyst exhibited higher surface area, smaller crystallite size, stronger visible light absorption and improved charge separation efficiency. The excellent activity reveals that BiOCl/TiO2 heterojunction is a promising visible-light-responsive photocatalyst.