Photocatalytic reduction of methyl orange on Au/TiO2 semiconductors

The photocatalytic reduction of Methyl Orange (MO) in aqueous solution by gold nanoparticles deposited by deposition-precipitation (DP) method on Degussa P25 was studied as a function of gold content. A shift to the red region on the UV spectra from 3.2 (Degussa P25) to 2.9-2.8 eV on the Au/TiO2 materials was observed by the presence of gold. High photocatalytic activity for the MO reduction using lamps of low energy UV-Vis emission (lambda=365, 418,435 nm) was obtained for the Au/TiO2 semiconductors, improving the rate constant of reduction in a factor up to 3.2 times compared to TiO2 P25 used as reference. These results evidence a very important role of gold in photoreduction reactions for organic compounds, in this particular case for the reduction of MO. (C) 2012 Elsevier B.V. All rights reserved.