Photocatalytic properties of BiOBr/BiOCl/AgBr ternary photocatalysts for degradation of RhB dye

Photocatalytic technology is a green technology using solar energy, which plays an important role in environmental protection. Bismuth compound BiOX (X = Cl, Br) is an excellent wide band gap semiconductor photocatalytic material but a greatly limited absorption of visible light. Silver bromide has strong photosensitivity but poor photocatalytic performance due to the serious recombination of photoelectron-hole pairs and the potential reaction between photoelectrons and silver ions. In this work, a series of BiOBr/BiOCl/AgBr ternary composite photocatalysts with excellent photocatalytic performance is synthesized by coprecipitation, and its photodegradation property in catalytic degradation of rhodamine B (RHB) dye under visible light irradiation is investigated. The results show that BiOBr/BiOCl/AgBr ternary heterojunction is successfully prepared experimentally, and the BiOBr/BiOCl/AgBr nanocomposites with 20 % molar fraction of AgBr (molar ratio of BiOBr/BiOCl =1:1) exhibits the best photocatalytic performance, its rate is 3.6 times of BiOCl, 3.1 times of BiOBr, and 55.9 times of AgBr. The formation of S-scheme heterojunction effectively reduces the recombination of photoelectron-hole pairs, resulting in a significant improvement in the photocatalytic performance of the ternary composite catalyst.