Adsorption and Reaction of CO and NO on Ir(111) under Near Ambient Pressure Conditions

Summary, in English

The adsorption and reaction of CO and NO on Ir(111) have been studied by near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) together with low-energy electron diffraction, scanning tunneling microscopy, and mass spectroscopy (MS). Under both ultrahigh vacuum (UHV) and NAP conditions CO molecules occupy on-top sites of the Ir(111) surface at room temperature (RT) by forming two-dimensional clusters. Exposure to NO under UHV conditions at RT induces partially dissociative adsorption, while NAP NO exposure leads to a Ir(111) surface that is covered by molecular NO. We conducted in-operando NAP-XPS/MS observation of the NO + ¹³CO reaction under a NAP condition as a function of temperature. Below 210 °C adsorption of NO is inhibited by CO, while above 210 °C the CO inhibition is released due to partial desorption of CO and dissociative adsorption of NO starts to occur leading to associative formation of N₂. Under the most active condition studied here the Ir surface is covered by a dense co-adsorption layer consisting of on-top CO, atomic N and O, which suggests that this reaction is not a NO-dissociation-limited process but a N₂/CO₂ formation-limited process.

• Author: K. Ueda; K. Suzuki; R. Toyoshima; Y. Monya; M. Yoshida; K. Isegawa; K. Amemiya; K. Mase; B. S. Mun; M. A. Arman; E. Grånäs; J. Knudsen; J. Schnadt; H. Kondoh
• Department/s: Synchrotron Radiation Research
• Publishing year: 2016-03-01
• Language: English
• Pages: 487-496
• Publication/Series: Topics in Catalysis
• Volume: 59
• Issue: 5-7
• Links: http://dx.doi.org/10.1007/s11244-015-0523-5
• Document type: Journal article
• Publisher: Springer
• Topic: Condensed Matter Physics (including Material Physics, Nano Physics); Inorganic Chemistry
• Keywords: CO adsorption; In-situ observation; Ir(111); NAP-XPS; NO + CO reaction; NO adsorption
• Status: Published
• ISBN/ISSN/Other: ISSN: 1022-5528