Interface atom mobility and charge transfer effects on CuO and Cu2O formation on Cu3Pd(111) and Cu3Pt(111)

Abstract

We bombarded Cu 3Pd (111) and Cu 3Pt (111) with a 2.3 eV hyperthermal oxygen molecular beam (HOMB) source, and characterized the corresponding (oxide) surfaces with synchrotron-radiation X-ray photoemission spectroscopy (SR-XPS). At 300K, CuO forms on both Cu 3Pd (111) and Cu 3Pt (111). When we increase the surface temperature to 500K, Cu 2O also forms on Cu 3Pd (111) , but not on Cu 3Pt (111). For comparison, Cu 2O forms even at 300K on Cu(111). On Cu 3Au (111) , Cu 2O forms only after 500K, and no oxides can be found at 300K. We ascribe this difference in Cu oxide formation to the mobility of the interfacial species (Cu/Pd/Pt) and charge transfer between the surface Cu oxides and subsurface species (Cu/Pd/Pt).