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

AgBr–BiOBr heterojunction photocatalysts with varying loadings of AgBr (<5.0 wt% AgBr) were synthesized through an effective co-precipitation method and used for the photodegradation of Rhodamine B under visible-light irradiation. Superior photocatalytic activities relative to that of pure BiOBr were observed on the AgBr–BiOBr catalysts with low AgBr loading (up to 0.5 wt%). Higher AgBr loadings (>0.5 wt%) lead to isolated AgBr species and reduced photocatalytic activity. Among such catalysts, the AgBr (0.2 wt%)–BiOBr exhibits the highest visible-light-responsive photoactivity, which can decolorize Rhodamine B within 30 min. 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.

Graphical abstractAgBr–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 0.2 wt% 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.Figure optionsDownload full-size imageDownload high-quality image (204 K)Download as PowerPoint slideHighlights► 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.