Surface spectroscopic studies of a model silica-supported copper catalyst: Adsorption and reactions of CO, H2O, and NO

A model silica-supported copper catalyst has been studied with temperature programmed desorption, x-ray photoelectron spectroscopy, infrared reflection–absorption spectroscopy, and scanning tunneling microscopy. The reactions of water and nitric oxide on the Cu/SiO2 catalyst were also investigated. The model catalyst was prepared by evaporating copper onto a silica thin film (∼100 Å) which was, in turn, supported on a Mo(110) surface. Copper forms small metallic clusters on the silica surface with a small fraction being partially oxidized. Water dissociates on the Cu/SiO2 catalyst to yield dihydrogen at 400 K and surface oxygen during temperature programmed reaction. Nitric oxide reacts with the model silica-supported copper catalyst to produce nitrous oxide and surface oxygen, which does not desorb until copper evaporates at high temperatures.