低温下H₂O和NO₂在θ-Al₂O₃/NiAl(100)超薄膜上的共吸附

Low temperature H2O and NO2 coadsorption on theta-Al2O3/NiAl(100) ultrathin films.

作者信息

Ozensoy Emrah, Peden Charles H F, Szanyi János

机构信息

Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-93, Richland, WA 99352, USA.

出版信息

J Phys Chem B. 2006 Apr 20;110(15):8025-34. doi: 10.1021/jp057534c.

DOI:10.1021/jp057534c

PMID:16610903

Abstract

The coadsorption of H(2)O and NO(2) molecules on a well-ordered, ultrathin theta-Al(2)O(3)/NiAl(100) film surface was studied using temperature programmed desorption (TPD), infrared reflection absorption spectroscopy (IRAS), and X-ray photoelectron spectroscopy (XPS). For H(2)O and NO(2) monolayers adsorbed separately on the theta-Al(2)O(3)/NiAl(100) surface, adsorption energies were estimated to be 44.8 and 36.6 kJ/mol, respectively. Coadsorption systems prepared by sequential deposition of NO(2) and H(2)O revealed the existence of coverage and temperature-dependent adsorption regimes where H(2)O molecules and the surface NO(x) species (NO(2)/N(2)O(4)/NO(2)(-),NO(3)(-)) form segregated and/or mixed domains. Influence of the changes in the crystallinity of solid water (amorphous vs crystalline) on the coadsorption properties of the NO(2)/H(2)O/theta-Al(2)O(3)/NiAl(100) system is also discussed.

摘要

采用程序升温脱附（TPD）、红外反射吸收光谱（IRAS）和X射线光电子能谱（XPS）研究了H₂O和NO₂分子在有序超薄θ-Al₂O₃/NiAl(100)薄膜表面的共吸附。对于分别吸附在θ-Al₂O₃/NiAl(100)表面的H₂O和NO₂单层，估计吸附能分别为44.8和36.6 kJ/mol。通过依次沉积NO₂和H₂O制备的共吸附体系揭示了存在覆盖度和温度依赖性吸附区域，其中H₂O分子与表面NOₓ物种（NO₂/N₂O₄/NO₂⁻、NO₃⁻）形成分离和/或混合域。还讨论了固体水结晶度变化（非晶态与晶态）对NO₂/H₂O/θ-Al₂O₃/NiAl(100)体系共吸附性能的影响。