Unusual reactivity of visible-light-responsive AgBr–BiOBr heterojunction photocatalysts

• Published in: Journal of catalysis 2012-09, Vol.293, p.116-125
• Main Authors: Kong, Liang, Jiang, Zheng, Lai, Henry H., Nicholls, Rebecca J., Xiao, Tiancun, Jones, Martin O., Edwards, Peter P.
• Format: Article
• Language: English
• Subjects: AgBr–BiOBr; Catalysis; Catalysts; Chemical synthesis; Chemistry; Deactivation; Exact sciences and technology; General and physical chemistry; Heterojunction; Irradiation; Photocatalysis; Photochemistry; Photodegradation; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Rhodamine B; Theoretical analysis; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Visible-light
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2012.06.011

AgBr–BiOBr p–n heterojunction photocatalysts have been synthesized and used for visible-light-responsive photodegradation. The low AgBr loading leads to superior catalytic activity compared to those with high loadings, which is prone to deactivation under visible-light irradiation. Among the studied catalysts, the 0.2wt% AgBr–BiOBr heterojunction exhibits the best activity in photodegradation Rhodamine B. Possible mechanisms of RhB photodegradation on the catalysts and their deactivation have been proposed on basis of experimental evidences and theoretical analysis. [Display omitted] ► AgBr–BiOBr p–n heterojunction photocatalysts exhibited unusual photocatalytic performance in Rhodamine B photodegradation. ► The deactivation phenomena in the AgBr-contained heterojunctions were reported for the first time. ► The working mechanism of the unusual photocatalytic performance was proposed. ► The deactivation mechanism of AgBr-contained catalyst was suggested. ► It extended the fundamental understanding of semiconductor p–n heterojunctions. AgBr–BiOBr heterojunction photocatalysts with varying loadings of AgBr (0.5wt%) lead to isolated AgBr species and reduced photocatalytic activity. Among such catalysts, the AgBr (0.2wt%)–BiOBr exhibits the highest visible-light-responsive photoactivity, which can decolorize Rhodamine B within 30min. However, these AgBr–BiOBr materials gradually lost their photoactivity in the cycling photocatalytic tests. Possible mechanisms for both the enhanced photocatalytic activity and deactivation of the AgBr–BiOBr heterojunctions were proposed on basis of theoretical speculation and experimental observations.