PHOTOCATALYTIC PROPERTIES OF HEXAGONAL WO3 NANOWIRES DECORATED WITH GOLD NANOPARTICLES

Hexagonal WO3 nanowires (h-WO3 NWs) (5-10 nm thick, 10 nm long) were prepared with microwave assisted hydrothermal synthesis using aqueous Na2WO4, (NH4)(2)SO4 and HCl. They were decorated with 5-10 nm gold nanoparticles, which were deposited by impregnation with HAuCl4 and NH4OH solutions and consecutive annealing at 350 degrees C. XRD, TEM, EDX and diffuse reflectance UV-Vis were applied for characterization, which demonstrated the presence of gold nanoparticles immobilized on the h-WO3 NWs. The photocatalytic activity of the as-prepared nanomaterials was tested in decomposing aqueous methyl orange. Without the heat treatment at 350 degrees C, the h-WO3-Au sample did not have an increased activity, compared to bare h-WO3 nanowires. However, after annealing the formation of gold nanoparticles was more intense, and thus the photocatalytic performance of the h-WO3-Au sample grew 2.5 times higher, due to suppressed electron-hole recombination.