Sodium citrate-assisted anion exchange strategy for construction of Bi2O2CO3/BiOI photocatalysts

Highlights: • Heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/BiOI microspheres were prepared via anion exchange. • Sodium citrate-assisted anion exchange for construction of composite photocatalysts. • Bi{sub 2}O{sub 2}CO{sub 3}/BiOI composites show high visible light photocatalytic activity. - Abstract: Bi{sub 2}O{sub 2}CO{sub 3}/BiOI heterojuncted photocatalysts were constructed through a facile partial anion exchange strategy starting from BiOI microspheres and urea with the assistance of sodium citrate. The content of Bi{sub 2}O{sub 2}CO{sub 3} in the catalysts was regulated by modulating the amount of urea as a precursor, which was decomposed to generate CO{sub 3}{sup 2−} in the hydrothermal process. Citrate anion plays a key role in controlling the morphology and composition of the products. The Bi{sub 2}O{sub 2}CO{sub 3}/BiOI catalysts display much higher photocatalytic activity than pure BiOI and Bi{sub 2}O{sub 2}CO{sub 3} towards the degradation of rhodamine B (RhB) and bisphenol A (BPA). The enhancement of photocatalytic activity of the heterojuncted catalysts is attributed to the formation of p–n junction between p-BiOI and n-Bi{sub 2}O{sub 2}CO{sub 3}, which is favorable for retarding the recombination of photoinduced electron-hole pairs. Moreover, the holes are demonstrated to be the main active species for the degradation of RhB and BPA.