Chemical reactivity of undercoordinated Rh atoms

The electronic structure and chemical reactivity changes of highly under-coordinated Rh atoms on a Pt(111) surface versus coordination number were studied by combining synchrotron radiation core level photoemission spectroscopy measurements performed at SuperESCA with density functional theory calculations. A remarkable linear relationship is found between core level shifted spectral components, originating from different atomic geometrical structures, and the corresponding induced d-band center shifts. This finding strongly underscores the relevance of core level shifts as reliable experimental descriptors of chemical reactivity, also for under-coordinated atoms in bimetallic transition metal systems.

The availability of an experimental tool capable of detecting local surface alloy configurations with enhanced chemical reactivity opens up the possibility to investigate more complex systems, such as nanostructured multicomponent alloy surfaces and bimetallic nanoclusters.