Interface atom mobility and charge transfer effects on CuO and Cu2O formation on Cu3Pd(111) and Cu3Pt(111)
AbstractWe bombarded $$\mbox{$\text{Cu}_{3}\text{Pd}(111)$}$$ Cu 3 Pd ( 111 ) and $$\mbox{$\text{Cu}_{3}\text{Pt}(111)$}$$ Cu 3 Pt ( 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 $$300\,\text{K}$$ 300 K , CuO forms on both $$\mbox{$\text{Cu}_{3}\text{Pd}(111)$}$$ Cu 3 Pd ( 111 ) and $$\mbox{$\text{Cu}_{3}\text{Pt}(111)$}$$ Cu 3 Pt ( 111 ) . When we increase the surface temperature to $$500\,\text{K}$$ 500 K , $$\mbox{$\text{Cu}_{2}\text{O}$}$$ Cu 2 O also forms on $$\mbox{$\text{Cu}_{3}\text{Pd}(111)$}$$ Cu 3 Pd ( 111 ) , but not on $$\mbox{$\text{Cu}_{3}\text{Pt}(111)$}$$ Cu 3 Pt ( 111 ) . For comparison, $$\mbox{$\text{Cu}_{2}\text{O}$}$$ Cu 2 O forms even at $$300\,\text{K}$$ 300 K on Cu(111). On $$\mbox{$\text{Cu}_{3}\text{Au}(111)$}$$ Cu 3 Au ( 111 ) , $$\mbox{$\text{Cu}_{2}\text{O}$}$$ Cu 2 O forms only after $$500\,\text{K}$$ 500 K , and no oxides can be found at $$300\,\text{K}$$ 300 K . 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).
