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

Abstract

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.