Operando coherent X-ray diffraction imaging of a single catalyst PtRh nanoparticle and surface X-ray diffraction of surface oxides

We aim to relate the Rh segregation-induced compositional strain state inside a single PtRh nanoparticle under catalytic CO oxidation/reduction conditions to the formation of surface oxides by using single nanoparticle surface X-ray diffraction. We will track the facet-dependent surface oxide formation of a single epitaxial Pt60Rh40 nanoparticle while following the catalytic activity by analysing the exhaust gas composition by online mass spectroscopy. The X-ray diffraction data will be correlated with UHV-STM measurements from the identical nanoparticle surface at DESY NanoLab in similar oxidizing/reducing environments. The experiment will elucidate how changes in the nanoparticle strain arise due to the formation of surface oxides and address the open questions on the atomic scale mechanisms in forming the nanoparticle facet-dependent surface oxides, and the role of Rh segregation towards the surface in the catalytic activity.