The CO-oxidation on Pd-rich surfaces of PdCu(110): hysteresis in reaction rates

✍ Scribed by M.S. Mousa; A. Hammoudeh; J. Loboda-Cackovic; J.H. Block

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 576 KB
• Volume: 96
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/1381-1169(95)80007-7

✦ Synopsis

The oxidation of carbon monoxide on PdCu( 110) single crystal alloy surfaces was investigated. During temperature variations, at constant CO and O2 pressures, regions of bistability could be detected by mass spectrometric reaction rate measurements, and a hysteresis was recorded. Initially, the top layer (TL) contained = 100% Pd atoms. After CO-oxidation experiments Cu/Pd ratio was increased up to = 0.7, as recorded by AES with surface region (SR) analysis of = 4 layers. This increase was due to a chemisorption induced segregation of Cu atoms from the bulk into the three subsurface layers (3SSL), that lie beneath the TL. After prolonged CO-oxidation experiments, with CO pressures up to = 10e3 mbar, the LEED pattern changed from a ( 1 x 1) pattern, for the clean surface, to a ~(2 X2) pattern. The CO-'IDS measurements showed that after CO-oxidation measurements all the TDS maxima obtained shifted to lower temperatures. Observation of hysteresis with this alloy surface indicates that it may be possible to observe kinetic oscillations during this reaction.