Reaction dynamics of catalytic CO oxidation on a Pt(113) surface

• Published in: Surface science 1998-10, Vol.416 (1), p.305-319
• Main Authors: Stefanov, Plamen K., Ohno, Yuichi, Yamanaka, Toshiro, Seimiya, Yoshiyuki, Kimura, Kazushi, Matsushima, Tatsuo
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbon monoxide; Catalysis; Catalytic reactions; Chemistry; Exact sciences and technology; General and physical chemistry; Platinum; Stepped surfaces; Surface reaction; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Thermal desorption; Time-of-flight spectra
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(98)00616-5

Angular and velocity distributions of desorbing CO 2 molecules formed by the CO oxidation on a Pt(113) surface were studied. Measurements were performed by means of angle-resolved thermal desorption combined with time-of-flight techniques. At initial reactant coverages of 0.10≤ Θ O≤0.30 and 0.08≤ Θ CO≤0.15, the CO 2 formation mostly occurs around 300–400 K during heating procedures. The working reaction sites are found to be both on the (111) terrace and the (100) step where the preferential occurrence of the reaction depends significantly on the reactant coverages. The translational temperature T 〈 E〉 of these CO 2 molecules reaches around 1300 K. No significant difference in T 〈 E〉 was found between the terrace and the step sites. On the other hand, at a high coverage of Θ O=0.35 and Θ CO=0.54, five CO 2 species are produced over a wide temperature range of 150–400 K. The reaction takes place both on the terrace and the step sites. T 〈 E〉 for these CO 2 molecules is higher than or around 1300 K on the terrace sites. A decrease in T 〈 E〉 of 150–270 K was found on the step sites in comparison with that on the terrace sites. The change of the reactant coverage affects to some extent the translational energy of the product CO 2. Such a difference in the translational energy is discussed through the energy transfer mechanism between the product molecule and the substrate surface.