Facile fabrication of efficient AgBr–TiO2 nanoheterostructured photocatalyst for degrading pollutants and its photogenerated charge transfer mechanism

Highlights: ► A microemulsion-like chemical precipitation is developed for AgBr–TiO2 composite. ► The composite displays effective charge transfers between AgBr and TiO2. ► A charge transfer mechanism in the AgBr–TiO2 composite is suggested. ► The suggested mechanism is responsible for the enhanced photocatalytic activity. - Abstract: A simple microemulsion-like chemical precipitation method has been successfully developed to construct effectively-contacted AgBr–TiO2 composite. The key of this method is the dual roles of Br− in the synthetic process, as linkers between cetyltrimethyl ammonium cation surfactants and nanocrystalline anatase TiO2 in the acidic condition, and as bromine sources to directly produce nanocrystalline AgBr on the surfaces of TiO2 by chemical precipitation. It is well demonstrated that the as-constructed AgBr–TiO2 nanoheterostructured composites display effective photogenerated charge transfer between AgBr and TiO2, favorable to improve charge separation, by means of the surface photovoltage technique in different atmospheres at the aid of outer electric fields, especially for the transient surface photovoltage technique in air. And also, the Br− in crystal lattice of AgBr could effectively capture photogenerated holes under illumination. These factors are well responsible for the enhanced activity for photocatalytic degradation of liquid phase aqueous phenol solution and gas phase acetaldehyde under either UV–visible or visible irradiation, and the stability of AgBr in the photocatalytic processes.