PREPARATION AND CHARACTERIZATION OF TUNGSTEN CHALCOGENIDE PHOTOCATALYSTS

Tungsten chalcogenides powders have been prepared by sulfidation of WO 3 with gaseous H2S. Different mixed WS2/WO3 systems have been obtained by varying the amount of initial WO3 powder, the time, or the tempera ture of sulfidation. The samples have been characterized by X-ray diff raction, determination of specific surface area, diffuse reflectance s pectroscopy, scanning electron microscopy, and EDX analysis. The photo catalytic degradation of phenol in aqueous suspensions has been employ ed to test the photoactivity of the powders. The results indicate diff erent behaviors of the samples, depending on the amounts of WO3 and WS 2 present in the powders. The coupling and the intimate contact of two different semiconductors with different energy levels is taken into a ccount to explain the enhanced photocatalytic behavior of the mixed sy stems in comparison with pure WO3 or WS2.