Operando NAP-XPS Observation and Kinetics Analysis of NO Reduction over Rh(111) Surface: Characterization of Active Surface and Reactive Species

Kohei Ueda, Kazuhisa Isegawa, Kenta Amemiya, Kazuhiko Mase, Hiroshi Kondoh

Research output: Contribution to journalArticle

6 Citations (Scopus)


NO reduction by CO on Rh(111) was investigated by near-ambient pressure X-ray photoelectron spectroscopy, mass spectrometry, and kinetic analysis. Under exposure to NO + CO mixed gases and with heating the surface from room temperature to 450 °C, NO dissociation and NO reduction reaction start simultaneously independent of gas pressure ratio of NO/CO, which indicates that NO dissociation triggers this reaction. From kinetic analyses based on observed adsorbate coverages under reaction conditions, the following two points are suggested: (i) NOhollow is a reactive species for N2 and N2O formation via N + NO reaction. (ii) At low temperatures, the N + NO reaction is dominant for N2 production, whereas above around 400 °C, the N + N reaction becomes dominant, which leads to an increase in N2 selectivity at the higher temperatures. Compared with the NO + CO reaction on Ir(111) surfaces, which exhibits a high N2 selectivity, the adsorption site of reactive NO and the availability of vacant surface sites could be key factors for the lower N2 selectivity for Rh(111).

Original languageEnglish
Pages (from-to)11663-11670
Number of pages8
JournalACS Catalysis
Publication statusAccepted/In press - 2018 Jan 1



  • kinetics
  • NO reduction
  • operando observation
  • reaction mechanism
  • Rh

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

Cite this