Effect of Water Washing Treatment on the Photocatalytic Activity of Au/TiO2 Catalysts

By using Au(S2O3)23- as the gold precursor, Au/TiO2 photocatalysts were prepared by water washing (W) and rotary evaporation (E) processes, respectively. The samples were characterized by UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic absorption flame emission spectroscopy (AAS). The photocatalytic activity of the samples was evaluated from the analysis of the photodegradation of methyl orange (MO). By using the water washing treatment, well-dispersed gold nanoparticles with the diameter of 2-5 nm were formed on the surface of TiO2, whereas only the gold coating was formed for rotary evaporation processes. The photocatalytic activity of Au/TiO2 photocatalysts is related to the preparation process. With a similar gold loading, the photocatalysts prepared by water washing showed higher photocatalytic activity compared to the catalysts prepared by rotary evaporation.