CO Oxidation over Platinum Nanoclusters: Unraveling the Role of the Cluster Size and the Supporting Surface

The present work focuses on the catalytic activity of Pt nanoclusters as well as single-atom Pt catalysts supported by TiO2 and Co3O4. We performed an extensive set of calculations based on density functional theory to investigate the CO oxidation reaction on Pt clusters supported on TiO2 and Co3O4 surfaces. We identified the catalytic active sites at the interface between the supported metal and the metal oxide substrate, and we determined different oxidation reaction pathways, proceeding either through the Langmuir-Hinshelwood (LH) or Mars-van Krevelen (MvK) mechanisms. Comparing clusters of different sizes, our calculations suggest that the Pt-1/TiO2 catalyst, where Pt is present as an adatom or substituting a Ti site, is the most active catalyst for CO oxidation. We find that the kinetics of the reaction on Pt nanoclusters is highly dependent on the size of the metal cluster but does not follow a well-defined trend. Moreover, the kinetics of the reaction is remarkably influenced by the type of supporting metal oxides.