The synthesis of a BiOClxBr1-x nanostructure photocatalyst with high surface area for the enhanced visible-light photocatalytic reduction of Cr(vi)

The photocatalytic reduction of poisonous Cr(vi) to environmentally friendly Cr(iii) driven by visible-light is highly foreseen. The construction of heterojunctions is a promising and solid strategy to tune the photocatalytic performance of BiOCl in the visible region. Herein, for the first time, we report Cr(vi) reduction by a BiOCl0.8Br0.2 composite produced via a facile in situ synthetic process at room temperature while making use of PVP (MW = 10000). In this study, a series of BiOClxBr1-x nanocomposites with different concentrations of chlorine and bromine have been prepared. The results show that BiOCl0.8Br0.2 has crystalline lattice, a large surface area (147 m(2) g(-1)), a microporous structure (0.377 cm(3) g(-1)), and very high chemical stability. It is revealed that the BiOCl0.8Br0.2 composite is much more active than those synthesized using different molar concentrations of chlorine and bromine. The DRS analysis and high photocurrent suggested that BiOCl0.8Br0.2 possessed absorption properties under visible light, which is beneficial for the efficient generation and separation of electron-hole pairs. In addition, we evaluated the photocatalytic activity of BiOCl0.8Br0.2 on the reduction of Cr(vi) under visible light irradiation and found that the obtained composite material exhibited a higher photocatalytic activity than single BiOCl or BiOBr without any decline in the activity after five cycles and is the best performing photocatalyst among those tested.