Role of Interfaces in the Thermal Reduction Process of the FeO/Cu2O/Cu(100) Surface

FeO­(111) islands grown on the Cu(100) substrate forming the FeO/Cu2O/Cu­(100) model surface and oxygen-covered Cu(100) (Cu2O/Cu­(100)) have been prepared and characterized by scanning tunneling microscopy (STM), synchrotron radiation photoemission spectroscopy (SRPES), and low-energy electron diffraction (LEED). Annealing the FeO/Cu2O/Cu­(100) and Cu2O/Cu­(100) surfaces shows distinct differences in thermal stability. As compared to the pure Cu2O/Cu­(100) surface, both STM and SRPES results indicate that the presence of FeO islands promotes the reduction of the oxygen-covered copper surface upon annealing. The absence of O2 signals in temperature-programmed desorption (TPD) experiments suggests that the oxygen adatoms diffuse into the copper bulk upon annealing up to 800 K and may react with segregated carbon atoms from bulk at temperatures higher than 800 K. Combining all these results, we conclude that the interface plays an important role in the properties of hybrid surface structures, and the obtained FeO/Cu2O/Cu­(100) and Cu2O/Cu­(100) surfaces may be used as model systems for studying the Cu–Fe-based catalysts.