Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 24: Teilchen und Cluster I

O 24.5: Talk

Saturday, March 5, 2005, 16:00–16:15, TU EB301

Efficient oxydation and Reduction of Ag nanoparticles — •Dong Chan Lim, Ignacio Lopez-Salido, Felix v. Gynz-Rekowski, and Young Dok Kim — Department of Physics, University of Konstanz, D.78457, Konstanz, Germany

Ag nanoparticles on SiO2/Si surfaces synthesized using Tollens reagents and subsequent acid-etching were studied using X-ray Photoelectron Spectroscopy (XPS) and Scanning Tunnelling Microscopy (STM). Ag nanoparticles smaller than 4-5nanometers show positive chemical shifts of the Ag 3d states with respect to the bulk values, in agreement with previous studies on Ag nanoparticles on titania and alumina. Ag nanoparticles smaller than 2-3 nanometers undergo reversible oxidation and reduction by reacting with H2O2/H2O and subsequent heating under vacuum to 150 ^∘C, which were not found for the bulk counterparts, demonstrating unique chemical properties of nanoparticles compared to the bulk counterparts.