SKM 2023 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 42: Poster: Nanostructures at Surfaces
O 42.11: Poster
Tuesday, March 28, 2023, 18:00–20:00, P2/EG
Oxidation of α-Al2O3(0001)-supported Pt-Rh alloy nanoparticles — •Ming-Chao Kao, Simon Chung, Thomas F. Keller, Vedran Vonk, and Andreas Stierle — Deutsches Elektronen-Synchrotron DESY, Center for x-ray and Nanoscience CXNS, Hamburg 22607, Germany
Metal oxide supported platinum-rhodium bimetallic alloy nanoparticles are widely deployed in the field of heterogeneous catalysis, where they often undergo oxidation-reduction cycles. To better understand the oxidation process, we monitored the nanoparticles in-situ by Grazing Incidence X-ray Diffraction (GIXRD) as a function of different alloy compositions. By heteroepitaxial growth, α-Al2O3(0001) substrate supported Pt, Rh, and Pt-Rh alloy nanoparticles were grown via molecular beam epitaxy. The samples were characterized by SEM, AFM, XRR, and GIXRD. The aim of this study is to uncover the oxide formation on the NPs as a function of oxygen partial pressure and temperature. The oxidation experiment is performed with an in-situ oxidation chamber, which enables experiments to be carried out up to an oxygen pressure of 1000 mbar at 450∘C. From the in-situ XRD experiments performed at constant temperature and increasing oxygen pressure, the following phenomena are deduced: particle sintering, selective oxidation, epitaxial strain, and the formation of Rh2O3 bulk oxide on (111)-oriented nanoparticles. Furthermore, composition-dependent changes together with selective oxidation and epitaxial strain were observed.