Tuning Surface Properties and Catalytic Performances of Pt-Ru Bimetallic Nanoparticles by Thermal Treatment

The surface structure and catalytic properties of Pt-Ru bimetallic catalysts with identical bulk composition can be continuously tuned by treatment at different temperatures. The activity of these catalysts in CO oxidation was positively related to the treatment temperature, but the opposite trend was observed for the solvent-free oxidation of benzyl alcohol. It was found that migration of Pt to the surface occurred when the treatment temperature was increased. During this process, the surface of the Pt-Ru nanoparticles changed from a Ru-rich surface to a Pt-rich surface. The electronic interactions between Pt and Ru became stronger with increased treatment temperature, and the amount of oxidized Pt species on the surface was higher for the samples treated at higher temperatures. Therefore, oxidized Pt species are more active in CO oxidation than other metallic species, but are less active in the selective oxidation of benzyl alcohol.