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

Abstract

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 BiOCl_0.8Br_0.2 composite produced via a facile in situ synthetic process at room temperature while making use of PVP (MW = 10 000). In this study, a series of BiOCl_xBr_1−x nanocomposites with different concentrations of chlorine and bromine have been prepared. The results show that BiOCl_0.8Br_0.2 has crystalline lattice, a large surface area (147 m² g⁻¹), a microporous structure (0.377 cm³ g⁻¹), and very high chemical stability. It is revealed that the BiOCl_0.8Br_0.2 composite is much more active than those synthesized using different molar concentrations of chlorine and bromine. The DRS analysis and high photocurrent suggested that BiOCl_0.8Br_0.2 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 BiOCl_0.8Br_0.2 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.