Molten Salt Synthesis of Bi₂WO₆ Powders and its Visible-Light Photocatalytic Activity

Bi₂WO₆ powders were synthesized by the molten salt method at 250-350 ºC using the mixture of Bi(NO₃)₃·5H₂O and Na₂WO₄·2H₂O as a precursor, and the mixture of LiNO₃ and NaNO₃ with a molar ratio of 27:33 as a molten salt, respectively. The effects of temperature and salt amount on the phase composition, morphology and photocatalytic activity under the visible light irradiation were investigated. The results revealed that pure phase Bi₂WO₆ powders could be synthesized at 350 ºC as the weight of molten salts were 2‒5 times as many as the precursor. Bi₂WO₆ powder synthesized with lower salt amount exhibited larger surface area, more abundant pores, narrower bandgap and lower PL intensity, all of which contributed a higher photocatalytic activity. The synthesized Bi₂WO₆ powder could degrade 0.01 mol/L Rhodamine-B solution by 97% after irradiation under visible light for 60 min. The obtained Bi₂WO₆ powder had a good photochemical stability and reusability, revealing potential application in environmental treatment.

Keywords:
Bi₂WO₆; Molten salt method; Photocatalysis; Environmental treatment