Low-Temperature Photocleaning of Sulfur-Poisoned Au Nanoparticles on Titanium Dioxide Film

Anatase-type TiO 2 films were formed on SiO 2 film-coated glass substrates by a sol-gel method.Nanometer-sized gold particles were highly dispersed on the surfaces of the TiO 2 film ͑Au/TiO 2 -TF͒ and TiO 2 particles ͑Au/TiO 2 -P͒ using a depositionprecipitation method.X-ray photoelectron spectra of Au/TiO 2 -TF adsorbed with sulfur from S 8 molecules indicated that the sulfurs are selectively adsorbed on the Au surfaces with the two kinds of chemisorption modes, atomic and molecular adsorption ͑S-Au/TiO 2 -TF͒.Light-irradiation ͑ ex Ͼ 300 nm͒ to S-Au/TiO 2 -TF and S-Au/TiO 2 -P in water at 298 K gave rise to desorption of the sulfur with the Au particle size almost maintained.Kinetic analysis showed that the rate constant for the sulfur desorption from S-Au/TiO 2 -TF in an opened reaction system is larger than that from S-Au/TiO 2 -P in a closed reaction system by a factor of ca.3.6.