Formation and characterization of Rh–Mo bimetallic layers on the TiO2(1 1 0) surface

The investigation of Rh, Mo and Rh–Mo nanosized clusters formed by physical vapor deposition on TiO2(1 1 0) single crystal was performed by X-ray Photoelectron Spectroscopy (XPS), Low Energy Ion Scattering (LEIS) and Auger Electron Spectroscopy (AES). There was no sign for site-exchange between Mo and Rh atoms during deposition of Mo onto Rh particles at 330 K. Mixing between Ti and Mo ions was facilitated at the Mo particle–titania interface due to reaction at 550–700 K. The redox process between titania and Mo deposit was hindered at 330 K by forming predeposited rhodium layer (ΘRh = 2.0 ML), but reached nearly the same extent as without Rh after moderate heating to 600 K. The encapsulation of Rh by titania was complete by about 700 K in the presence of 1.2 ML Mo, in case of Mo-predeposition and Mo-postdeposition as well. Elevating the temperature of TiO2/Rh–Mo layers above 700 K, these metals form alloy at the Mo–Rh interface irrespective of deposition sequences.