Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 17: Adsorption on Metal Surfaces
O 17.3: Talk
Monday, March 7, 2016, 15:30–15:45, H6
CO adsorption on graphene supported Pt, Rh and Pt-Rh nanoparticles — •Marcus Creutzburg1,2, Heshmat Noei1, and Andreas Stierle1,2 — 1Deutsches Elektronen-Synchroton (DESY), Notkestraße 85, Hamburg, Germany — 2Fachbereich Physik, Universität Hamburg, Jungiusstraße 9, Hamburg, Germany
Small metal nanoparticles dispersed on porous substrates have gained increasing interest in surface science because of their widespread applications, especially in heterogeneous catalysis. It was previously shown that nanoparticles grown by UHV vapor deposition of material form ordered arrays on graphene substrates using the moiré of graphene/Ir(111) as a template. The size and shape of these nanoparticles can be carefully controlled with diameters smaller than 2 nm on graphene/Ir(111) by the amount of deposited material. In this contribution, we study the adsorption of CO on Pt, Rh and Pt-Rh core-shell nanoparticles on graphene/Ir(111) using vibrational spectroscopy under UHV conditions. The UHV-IRRAS data demonstrate one adsorption site for the two-layered Pt and Rh nanoparticles, which is assigned to CO on-top edge sites of the nanoparticles, while for the three-layered Pt and Rh nanoparticles the adsorption of CO on-top edge sites is only preferred at low CO coverages. For higher CO coverages a second (additional) adsorption site with higher wavenumbers is observed, which is interpreted as on-top adsorption sites on nanoparticle terrace atoms. Three-layered Pt-Rh core-shell nanoparticles show CO adsorption on-top of Rh edge and corner atoms at low CO coverages and on-top of Pt terrace sites at higher CO coverages.