ETHYLENE ADSORPTION AND DECOMPOSITION ON PLATINUM SINGLE-CRYSTAL SURFACES

The adsorption of ethylene on Pt has been studied in the temperature range 90-500 K using a field emission probe-hole microscope. The emitter regions examined are the Pt(111), (110), the stepped (533) and the open (210) surfaces. Work function changes brought about by exposure to ethylene have been measured under various experimental conditions. The influence of the surface structure on the various processes taking place on Pt has been examined by comparing the temperature dependence of the emission properties on the four Pt surfaces previously exposed to ethylene. Our results show that the various transformations taking place in the adlayer occur at a lower temperature on the stepped surface than on the close-packed (111) surface while the (110) and (210) surfaces are even more active than the (533) surface. Arguments are presented that decomposition of the adsorbed ethylene (CH and CC bond breaking) occurs more easily on Pt(210) and (110) than on Pt(533) while the Pt(533) surface is more active than Pt(111). © 1979.