A SURFACE SPECTROSCOPIC STUDY OF METAL SUPPORT INTERACTIONS - MODEL STUDIES OF COPPER ON THIN SIO2-FILMS

The metal-support interactions for a model silica-supported copper catalyst have been studied using temperature-programmed desorption, X-ray photoelectron and infrared reflection-absorption spectroscopies under ultrahigh vacuum conditions. The model catalyst support was prepared by synthesizing a thin SiO2 film (approximately 100 angstrom) on a Mo(110) surface. Copper was then evaporated onto the SiO2 films. A small amount of copper (< 0.1 monolayer) is partially oxidized at the Cu/SiO2 interface with the remainder forming 3D-clusters. The desorption energy of copper from the SiO2 is found to depend markedly on copper coverage (cluster size).