Urea-assisted synthesis of ultra-thin hexagonal tungsten trioxide photocatalyst sheets

Ultra-thin hexagonal tungsten trioxide (h-WO₃) sheet has been synthesized with the assistance of urea. Some measurements have been carried out for sample characterization, such as XRD, TEM, AFM, FT-IR, Raman, XPS, and Zeta potential. It is shown that urea not only acts as pH regulator and stabilizer for the generation of a metastable hexagonal phase, but also plays an important role on the formation of ultra-thin sheet. The detailed formation mechanism has been discussed. The TEM and AFM tests show the thickness of ultra-thin h-WO₃ nanosheet which is about 5 nm and the size is about 20–120 nm. Such size is favorable for photocatalytic reaction. Photodegradation RhB is carried out for investigating the photocatalytic activity of as-prepared sample. The ultra-thin h-WO₃ sheet displays superior photocatalytic activity, more excellent photocatalytic activity than other shape samples due to its unique structure.