Structural and electronic studies of supported Pt and Au epitaxial clusters on tungsten oxide surface

In the present paper we investigated the growth and electronic properties of Pt or Au clusters and formation of Pt–Au bimetallic clusters prepared “in-situ” on tungsten oxide surface by physical deposition under vacuum. The epitaxial tungsten oxide thin films were prepared by oxidation of W(110) single-crystal surface using a RF oxygen plasma source followed by thermal annealing. The chemical state of the system, the interaction between deposit and substrate and formation of Pt–Al alloy were investigated by photoelectron spectroscopy excited by synchrotron radiation (SRPES) and K;α X-ray source (XPS). We found that in contrary to Au clusters the Pt ones strongly interacts with the substrate. Deposition of both Pt and Au on the surface at the substrate temperature of 300 °C gave rise to the formation of bimetallic core–shell clusters. The detail structure of the bimetallic system depends on the order of deposited metals. These findings can explain some properties of Pt/WOx and Au/WOx as well as Pt–Au/WOx bimetallic catalysts and gas sensors.