Preparation and Characterization of WO3 Nanosheets and Au/WO3 Nanocomposite for Rabid Photocatalytic degradation of methylene blue dye

The sol-gel technique is employed for the synthesis of tungsten trioxide (WO3) nanosheets. The Au/WO3 nanocomposite is prepared using laser ablation employing an Nd-YAG laser operating at a wavelength of 1064 nm and utilizing gold metal. The SEM images demonstrate that WO3 was formed as nanosheets with a thickness between 36nm and 80nm.  X-ray diffraction (XRD) patterns confirmed the monoclinic crystal structure and high crystallinity of the WO3 structure. The optical absorption of both WO3 nanosheets and Au/WO3 nanocomposite exhibited a pronounced absorption edge, with an energy gap of 2.52 eV and 2.41 eV, respectively. The photocatalytic activity of WO3 nanosheets and Au/WO3 nanocomposite was determined by degrading Methylene blue (MB) dye under visible light irradiation using different catalyst doses and pH values. The WO3 nanosheets and Au/WO3 nanocomposites that were prepared demonstrate a fast degradation of MB dye. The highest photodegradation efficiency (PDE) of MB dye was 75.9% when 0.05 g of Au/WO3 nanocomposite was exposed to 7 pH for 6 min of irradiation. Nevertheless, an increase of pH led to a corresponding rise in PDE. Particularly, the PDE values reached 85.5% and 95.7% when using 0.1 g of WO3 nanosheets and Au/WO3 nanocomposite, respectively, under the conditions in a pH level of 12 and an irradiation duration of 6 minutes.