Gold-titania/protonated zeolite nanocomposite photocatalysts for methyl orange degradation under ultraviolet and visible irradiation

Gold-titania/protonated zeolite (Au–TiO2/HZSM-5) composite photocatalysts were prepared via the sol–gel and impregnation processing. The structural features of the photocatalysts were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and ultraviolet visible diffuse reflection spectroscopy (UV–vis); the adsorption and photo-degradation of Methyl Orange (MO) were studied in the aqueous solution. The results showed that the nanoAu particles were incorporated in TiO2/HZSM-5. The introduction of Au particles not only maintained the adsorption capacity of photocatalysts, but also promoted the photodegradation efficiency of Methyl Orange (MO). The effects of Au content, TiO2 content, catalyst amount and calcination temperature were examined and the repeatability of photocatalytic activity was also tested. Moreover, the Methyl Orange (MO) photodegradation activity of 0.32%Au-25%TiO2/HZSM-5 nanocomposites is the best. A plausible mechanism is proposed for the route of degradation.