METALLIC SURFACES UNDER ELEVATED GAS PRESSURE STUDIED IN SITU BY SCANNING TUNNELING MICROSCOPY: O_2, H_2/Au(111); CO/Au(110)

摘要

We have built an experimental set-up including a scanning tunneling microscope in order to study the behaviour of catalytic surfaces in environmental conditions close to that needed in catalysis (pressure of gas, temperature). We have studied gold surfaces under gas pressure since gold was recently found to be highly active in the low temperature catalytic oxidation of carbon monoxide without combustion of hydrogen. We have followed real-time morphological modifications of Au(111) surfaces under elevated pressures (1 bar) of hydrogen and oxygen. We have also studied the adsorption of CO on Au(110)-(1x2) reconstructed surface and observed in-situ by STM the dramatic change of the morphology of the terraces under the influence of the CO pressure (up to 670 mbar) on the structure of the surface. Complementary XPS and IRRAS measurements were also performed and show CO dissociation the surface.