Reactivity of a Thick BaO Film Supported on Pt(111): Adsorption and Reaction of NO2, H2O, and CO2

详细信息    查看全文

• 作者：Kumudu Mudiyanselage ; Cheol-Woo Yi ; Jnos Szanyi
• 刊名：Langmuir
• 出版年：2009
• 出版时间：September 15, 2009
• 年：2009
• 卷：25
• 期：18
• 页码：10820-10828
• 全文大小：1031K
• 年卷期：v.25,no.18(September 15, 2009)
• ISSN：1520-5827

文摘

Reactions of NO₂, H₂O, and CO₂ with a thick (>20 monolayer equivalent (MLE)) BaO film supported on Pt(111) were studied with temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). NO₂ reacts with a thick BaO layer to form surface nitrite−nitrate ion pairs at 300 K, while only nitrates form at 600 K. In the thermal decomposition process of nitrite−nitrate ion pairs, first nitrites decompose and desorb as NO. Then nitrates decompose in two steps: at lower temperature with the release of NO₂ and at higher temperature, nitrates dissociate to NO + O₂. The thick BaO layer converts completely to Ba(OH)₂ following the adsorption of H₂O at 300 K. Dehydration/dehydroxylation of this hydroxide layer can be fully achieved by annealing to 550 K. CO₂ also reacts with BaO to form BaCO₃ that completely decomposes to regenerate BaO upon annealing to 825 K. However, the thick BaO film cannot be converted completely to Ba(NO_x)₂ or BaCO₃ under the experimental conditions employed in this study.