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

Supported metallic 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 morphology is not necessarily the most catalytically active. We study here how the location of O-vacancies in TiO₂ relative to a Ru₁₀ cluster may affect its morphology using a thorough sampling at the DFT+U level of theory. The vacancies are preferentially located below the cluster and their presence induces a decrease of the Ru/TiO₂ contacts since the Ru₁₀ cluster moves from oblate geometries to more spherical geometries. Importantly, this paper highlights the existence of energetically stable cluster morphologies that present previously unknown under-coordinated Ru atoms available for catalysis.