Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 20: Nanostructures at Surfaces II
O 20.12: Vortrag
Montag, 31. März 2014, 18:45–19:00, WIL B321
Nanooxidation - Oxidation kinetics of small Rh nanoparticles — •Patrick Müller1,2, Heshmat Noei1,2, Thomas F. Keller1, Björn Arndt1,2, Peter Wochner3, Roberto Felici4, and Andreas Stierle1,2 — 1Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany — 2Fachbereich Physik, Universität Hamburg, 20355 Hamburg, Germany — 3Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany — 4European Synchrotron Radiation Facility, 38043 Grenoble, France
Metal nanoparticles (NPs) are used in many technical fields such as heterogeneous catalysis and biosensors. Although the oxidation behaviour of transition metal surfaces was studied in depth in the past, the oxidation kinetics of small NPs is poorly understood. The traditional oxidation theory proposes different growth laws for single crystal surfaces, but does not take into account the properties of NPs like their shape. In recent studies the oxidation theories were modified to also comprise geometrical aspects as the curvature of the NP by using a spherical model [1,2]. Our experiments focused on the systematic study of the size dependence of the oxidation kinetics of half spherical Rh NPs with particles sizes from 2 to 12 nm on sapphire at 573 K and 10−3 mbar oxygen pressure. The experiments were carried out at the MPI beamline at ANKA and beamline ID03 at the ESRF. We employed x-ray reflectivity and grazing incidence small angle x-ray scattering. Our results demonstrate a dramatic change in the oxidation kinetics for the smallest NPs. [1] A. Ermoline, E. L. Dreizin, Chem. Phys. Lett. 505, 47 (2011);[2] A. T. Fromhold Jr., J. Phys. Chem. Solids 49, 10 (1988)