Abstract: Combined with supercritical ethanol drying, anatase Au/TiO2 and Au-TiO2 with 0.2%(atom fraction) Au content were synthesized by the deposition-precipitation (DP) and the coprecipitation (CP) respectively, and characterized with XRD, BET, Raman, XPS, and TEM. The activity was investigated using the photocatalytical degradation of methyl orange as probe. The results showed that the Au/TiO2 dried at 110 ℃ had a very high photocatalytic activity, the first-order reaction rate constans were 3.2 and 4.1 times higher than those of pure TiO2 and commercial Degussa-P25 photocatalyst respectively. The activity of Au/TiO2 decreased after thermal treatment or reduction in hydrogen due to the reduction of Au3+. A suitable amount of Au3+ on the surface of TiO2 as a trap for photogenerated electron can be beneficial to improving the efficiency of the photocatalytic oxidation process. The Au-TiO2 did not improve the photocatalytic activity of TiO2. The sample with higher crystallization degree after thermal treatment had the higher activity. But when the sample was treated in 800 ℃, the Au would be reduced and moved from the bulk to the surface of TiO2, which resulted in the increase of lattice oxygen vacancy and the decrease of activity.

Key words: Gold, Doping, Oxidation state, Anatase TiO2, Methyl orange, Photocatalysis