The nature of the interactions between Pt and TiN, a material of interest as a support for proton-exchange-membrane (PEM) fuel cell applications, have been examined in ultrahigh vacuum (UHV) using X-ray photoelectron spectroscopy (XPS). For small amounts of Pt, a reaction takes place yielding XPS features consistent with formation of the intermetallic compound PtTi. Increasing the amount of Pt shifts the 4f 72 electron binding energy toward that of metallic Pt. Complementary angle-resolved XPS revealed that Pt remains in the outer surface region of the resulting multicomponent film. The results show that TiN layers with a thickness of only ca. 1 nm already form an effective barrier to Pt diffusion at room temperature.
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