Photocatalytic activity of Au/TiO2 nanocomposite for azo-dyes degradation

The structural properties of Au/TiO2 catalyst were studied by X-ray diffraction, UV-visible diffuse reflectance, photoluminescene, scanning transmission and electron microscope, and temperature programmed reduction. The photocatalytic activity of the catalysts was evaluated for the degradation of various azo-dyes such as methylene blue, methyl orange, reactive blue-4, and eosin-B under solar irradiation. It was found that TiO2 catalyst modified with gold exhibits higher percentage of degradation compared to starting TiO2. For example, TiO2 showed 35% of methyl orange degradation whereas gold modified TiO2 possessed 82%. Effect of different parameters such as pH and dye concentration has been evaluated and the photocatalytic activity was correlated with physico-chemical properties. The dye degradation rate followed first order kinetics.