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

Bi2O2CO3/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 Bi2O2CO3 in the catalysts was regulated by modulating the amount of urea as a precursor, which was decomposed to generate CO32− in the hydrothermal process. Citrate anion plays a key role in controlling the morphology and composition of the products. The Bi2O2CO3/BiOI catalysts display much higher photocatalytic activity than pure BiOI and Bi2O2CO3 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-Bi2O2CO3, 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.