Abstract: A PtRu alloy thin-film used for catalytic electrodes of fuel cells was fabricated by ion beam sputtering (IBS). The structure, surface layer structure, chemical composition, surface chemical state, and morphology of the PtRu alloy thin-film were characterized using X-ray diffraction (XRD), grazing incidence X-ray diffraction (GIXD), X-ray photoelectron spectroscopy(XPS), and atomic force microscopy (AFM). It was shown that the surface chemical state and structure in the top layer (from 15-40 nm) of PtRu alloy thin-film were changed due to the strong interaction between Pt+ and Ru+ during the ion beam sputtering deposition process, which also affected the catalytic activity of the PtRu alloy thin-film. In particular, when the atomic ratio of xPt/xRu was 0.64, enrichment of the Ru solid solution and amorphous phase Pt39Ru61 were observed on the surface layer of PtRu alloy thin-film.

Key words: Ion beam sputtering, PtRu alloy thin-film, Surface layer structure, Preferred orientation, Catalytic activity