Adsorption and decomposition of Mo(CO)6 on thin Al2O3 films: fabrication of metallic molybdenum model catalyst

An ultra-thin and homogeneous alumina film is prepared by deposition and oxidation of aluminum on a platinum substrate under ultrahigh vacuum conditions. Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy (HREELS) demonstrate that this film is completely stoichiometric and characteristic of Al2O3. Temperature-programmed desorption (TPD) and XPS characterization show that the Mo(CO)6 decomposes and leaves molybdenum with C and O contaminants on the Al2O3 film at 700 K. Subsequent heat treatment at 1200 K results in the formation of a model surface of metallic-molybdenum-modified alumina, which could be applied to simulate the activation of CH4.