Infrared reflection absorption spectral study for CO adsorption on Pd/Pt(111) bimetallic surfaces
Infrared reflection absorption spectral study for CO adsorption on Pd/Pt(111) bimetallic surfaces
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DOI：
10.1016/j.apsusc.2009.05.070
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发表时间：
2009-11-30
影响因子：
6.7
通讯作者：
Wadayama, T.
中科院分区：
文献类型：
--
作者：
Todoroki, N.;Osano, H.;Wadayama, T.
使用红外反射吸收光谱（IRRAS）来研究一氧化碳（CO）在0.15 nm-0.6 nm厚的Pd沉积的Pt（111）表面上的吸附：Pd-x/Pt（111）（其中x是以纳米计的Pd厚度），其使用分子束外延方法在343 K、473 K和673 K的衬底温度下制造。在343 K下制备的Pd 0.15 -0.6（nm）/Pt（111）表面的反射高能电子衍射（RHEED）测量表明Pd在干净的Pt（111）上外延生长，具有与Pt（111）几乎相同的晶格常数。在室温下将1.0 L CO暴露于清洁Pt（111）在2093和1855 cm（1）处产生线性键合和桥键合的CO-Pt带。CO暴露的Pd-x/Pt（111）表面的CO-Pt带强度随着Pd厚度的增加而降低。对于343 K下沉积的Pd-0.3nm/Pt（111），由CO-Pd桥键引起的1933 cm（1）带增强了光谱强度。在Pd-0.6nm/Pt（111）中，Co-Pt线性键合带（2090 cm（1））几乎消失，而桥键合带占主导地位。随着衬底温度的升高，CO-Pt/CO-Pd的相对谱带强度增加。在673 K下沉积的Pd-0.3nm/Pt（111）薄膜中，Co-Pt线性键合和桥键合的CO-Pd带分别位于2071和1928 cm（1）处。程序升温脱附（TPD）谱表明，CO在Pt位上的脱附信号强度降低，并向Pt位移动约100 nm。20 K至比清洁Pt（111）更低的温度。我们讨论了CO在Pt（111）面上的吸附行为。(C)2009爱思唯尔有限公司版权所有。
Infrared reflection absorption spectroscopy (IRRAS) was used to investigate carbon monoxide (CO) adsorption on 0.15 nm-thick-0.6 nm-thick Pd-deposited Pt(1 1 1) bimetallic surfaces: Pd-x/Pt(1 1 1) (where x is the Pd thickness in nanometers) fabricated using molecular beam epitaxial method at substrate temperatures of 343 K, 473 K, and 673 K. Reflection high-energy electron diffraction (RHEED) measurements for Pd0.15-0.6 (nm)/Pt(1 1 1) surfaces fabricated at 343 K showed that Pd grows epitaxially on a clean Pt(1 1 1), having an almost identical lattice constant of Pt(1 1 1). The 1.0 L CO exposure to the clean Pt(1 1 1) at room temperature yielded linearly bonded and bridge-bonded CO-Pt bands at 2093 and 1855 cm (1). The CO-Pt band intensities for the CO-exposed Pd-x/Pt(1 1 1) surfaces decreased with increasing Pd thickness. For Pd-0.3nm/Pt(1 1 1) deposited at 343 K, the 1933 cm (1) band caused by bridge-bonded CO-Pd enhanced the spectral intensity. The linear-bonded CO-Pt band (2090 cm (1)) almost disappeared and the bridge-bonded CO-Pd band dominated the spectra for Pd-0.6nm/Pt(1 1 1). With increasing substrate temperature during the Pd depositions, the relative band intensities of the CO-Pt/CO-Pd increased. For the Pd-0.3nm/Pt(1 1 1) deposited at 673 K, the linear-bonded CO-Pt and bridge-bonded CO-Pd bands are located respectively at 2071 and 1928 cm (1). The temperature-programmed desorption (TPD) spectrumfor the 673 K-deposited Pd-0.3nm/Pt(1 1 1) showed that a desorption signal for the adsorbed CO on the Pt sites decreased in intensity and shifted ca. 20 K to a lower temperature than those for the clean Pt(1 1 1). We discuss the CO adsorption behavior on well-defined Pd-deposited Pt(1 1 1) bimetallic surfaces. (C) 2009 Elsevier B.V. All rights reserved.