Rod-like Bi4O7 decorated Bi2O2CO3 plates: Facile synthesis, promoted charge separation, and highly efficient photocatalytic degradation of organic contaminants.

In this manuscript, rod-like Bi4O7 decorated Bi2O2CO3 plates were fabricated for the first time. Compared with pristine Bi2O2CO3, the tight decoration of Bi4O7 over Bi2O2CO3 plates not only strengthened the visible light absorption, but also enhanced the separation efficiency of photo-generated carriers. As expected, the heterostructured Bi4O7/Bi2O2CO3 composites have exhibited highly promoted photocatalytic activities in decomposing Rhodamine B (RhB) under visible light. The BOBC-2 sample displayed the best activity with a reaction rate constant of 0.0245 min-1, which was 3.8 times higher than that of pure Bi4O7. Besides RhB, the Bi4O7/Bi2O2CO3 composites also displayed superior activity toward colorless contaminants with stable chemical structures, such as phenol, p-tert-butylphenol, and o-phenylphenol. The activity enhancement should be ascribed to the proper energy levels of the materials and formation of heterojunction at their interfaces, which could facilitate the charge transfer and promote the separation efficiency. Following transient photocurrent response, electrochemical impedance spectroscopy, and photoluminescence emission tests all verified this. In addition, controlled experiments using various radical scavengers proved that O2- and h+ played the chief role in decomposing organic pollutants. This work may provide a new method for constructing Bi-based heterostructured photocatalysts with high activity.