Synthesis of WO3 catalytic powders: evaluation of photocatalytic activity under NUV/visible light irradiation and alkaline reaction pH

WO3 catalytic powders were successfully syn- thesized from tungstic acid and sodium tungstate precur- sors by simple, low-cost sol-gel and precipitation methods followed by low-temperature hydrothermal treatment. WO3 crystallization process was completed with calcina- tion of the samples at 500 and 700 � C. The effects of synthesis method and calcination temperature on the structural, morphological characteristics and surface area of the samples were investigated. The photocatalytic activity of WO3 samples was evaluated by the discol- oration efficiency of methylene blue (MB) aqueous solu- tions under NUV/visible light irradiation at various reaction pH values. The photocatalytic discoloration effi- ciency of MB was found to increase with increasing reaction pH, with best results obtained at pH 9. Graphical Abstract