Construction of a hydrangea-like Bi2WO6/BiOCl composite as a high-performance photocatalyst

The microstructure design and construction of a heterojunction are major strategies for enhancing the photocatalytic activity of semiconductors. Herein, Bi2WO6 flower spheres were synthesized and acted as a porous template for depositing BiOCl to fabricate a Bi2WO6/BiOCl composite photocatalyst. Through changing the concentrations of the Bi3+ and Cl- precursors, a hydrangea-like Bi2WO6/BiOCl composite with a porous nanostructure was synthesized. Rhodamine B (RhB), methylene blue (MB) and tetracycline hydrochloride (TCH) were selected as simulated pollutants for degradation by the photocatalyst. Under the irradiation of visible light, the optimized Bi2WO6/BiOCl composite removes almost 100% of RhB from solution in 60 min, 88% of MB in 75 min, and 90% of TCH in 90 min, much better than the performances of pure Bi2WO6 or BiOCl. The excellent photocatalytic activity of the Bi2WO6/BiOCl composite can be attributed to its hydrangea-like nanostructure and Bi2WO6/BiOCl heterojunction. On the one hand, the hydrangea-like structure promotes the physical adsorption of organic molecules on the photocatalyst. On the other hand, the Bi2WO6/BiOCl heterojunction broadens the light absorption range, accelerates the separation of photogenerated electrons and holes, and decreases charge transfer resistance, further improving the photocatalytic activity of the material. O-2(-) and OH reactive species were generated under visible light irradiation, which promoted the fast degradation of organic pollutants. Based on the reactive species and the position of its conduction/valence band, the photocatalytic mechanism of the Bi2WO6/BiOCl composite was proposed as a Z-scheme heterojunction transfer mode.

Automated summary

The study successfully synthesized Bi2WO6/BiOCl composite photocatalysts through microstructure design and construction of heterojunctions, which exhibited excellent photocatalytic activity due to their unique nanostructure and heterojunction, facilitating efficient separation of photogenerated electrons and holes as well as physical adsorption of organic molecules. The generation of reactive species under visible light irradiation and the proposed Z-scheme heterojunction transfer mode further elucidate the photocatalytic mechanism of the composite material.