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O: Fachverband Oberflächenphysik
O 28: Heterogeneous catalysis II
O 28.8: Talk
Tuesday, March 27, 2012, 12:15–12:30, MA 042
Oxidation of Platinum Nanoparticles on Gallium Nitride Surfaces: the effect of semiconductor doping on nanoparticle reactivity — •Susanne Schäfer1, Sonja A. Wyrzgol2, Michael Hävecker3, Axel Knop-Gericke3, Johannes A. Lercher2, Ian D. Sharp1,4, and Martin Stutzmann1,2 — 1WSI, Technische Universität München, Am Coulombwall 4, 85748 Garching — 2Catalysis Research Center, Technische Universität München, Garching — 3Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin — 4Joint Center for Artificial Photosynthesis, LBNL, Berkeley, USA
Platinum nanoparticles supported on p- and n-type GaN are investigated as novel hybrid systems for the electronic control of catalytic activity. In-situ oxidation and reduction were studied with high pressure XPS. The experiments revealed that the underlying wide bandgap semiconductor has a large influence on the surface properties and reactivity of supported nanoparticles. For as-deposited Pt cuboctahedra supported on n-type GaN, a higher fraction of oxidized surface atoms was observed compared to cuboctahedral particles supported on p-type GaN. Under an oxygen atmosphere, immediate oxidation was recorded for nanoparticles on n-type GaN, whereas little oxidation was found for nanoparticles on p-type GaN. Together, these results indicate that changes of the Pt chemical activity under X-ray irradiation are dependent on the type of GaN doping. The strong nanoparticle-support interaction is consistent with charge transfer of X-ray photogenerated free carriers at the GaN/Pt interface and suggests that GaN is a promising support material for photocatalysis and catalysis on demand.