Size Effects On The Desorption Of O2 From Au2O 3/Au\u3csup\u3e0\u3c/sup\u3e Nanoparticles Supported On Sio2: A Tpd Study

This article contains an in-depth study of the kinetics of O2 desorption from preoxidized size-selected gold nanoparticles (NPs) of average size ∼1.5 and ∼5 nm synthesized by micelle encapsulation and supported on SiO2. Thanks to the narrow NP size distributions achieved using our preparation route, information on the effect of the nanoparticle size on the reaction kinetics could be obtained by temperature programmed desorption (TPD). In addition, the validity of different TPD analysis methods (Redhead, heating rate variation, Arrhenius plots, and the complete analysis) to extract meaningful kinetic parameters on supported NPs is discussed. From the different analysis methods, activation energies for O2 desorption of E d = 1.3 ± 0.2 eV and 1.7 ± 0.1 eV were obtained for the ∼5 and ∼1.5 nm Au NPs, respectively. These differences in the activation energies are directly related to the nanoparticle size and not to nanoparticle-support interactions. © 2008 American Chemical Society