Influence of oxygen vacancies on the morphology of Ru10 clusters supported on TiO2

Small metal clusters used in catalysis present high degrees of morphological diversity that has to be accounted for in order to understand catalytic processes correctly, as the most stable morphologies are not necessarily the most catalytically active. In this paper Ru clusters supported over TiO2 were investigated at a high level of sampling using DFT+U. This allows for the study of the location of O-vacancies in TiO2 relative to the Ru cluster, showing that the vacancies form immediately under the clusters and affect the morphology of the clusters. Furthermore, the shape of supported Ru clusters is analyzed, showing that vacancies lead the clusters to diminish their contact with the TiO2 surface and move from oblate geometries to more spherical geometries. Lastly, this paper highlights the existence of energetically stable cluster morphologies that present previously unknown under-coordinated Ru atoms available for catalysis.