Interaction of CO with clean and oxygen covered PdCu(110) single crystal alloy
Interaction of CO with clean and oxygen covered PdCu(110) single crystal alloy
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DOI：
10.1016/s0042-207x(98)00471-0
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发表时间：
1999-07-01
期刊：
影响因子：
4
通讯作者：
Loboda-Cackovic, J
中科院分区：
文献类型：
--
作者：
Hammoudeh, A;Mousa, MS;Loboda-Cackovic, J
用开尔文探针功函数法研究了PdCu(110)单晶合金在化学吸附CO时可能发生的成分变化。此外，应用相同的技术研究了该合金不同表面组成的表面在CO氧化反应中的反应活性。结果表明，在富铜表面，CO的化学吸附导致了Pd向表面的偏析。较高的CO压力(10(-4)-10(-3)mbar)也会导致表面分离仍未确定的污染物，其特征是180 eV处的俄歇电子能谱信号。在CO氧化实验中，与纯Pd相比，PdCu合金的反应活性较低，即使最外层完全由Pd原子组成。随着铜浓度的增加，反应活性进一步降低。PdCu合金反应活性较低的原因是在该体系中观察到Pd向Cu的电荷转移，从而降低了CO在合金表面的“修饰”Pd上的吸附热焓(可能是吸附系数)。(C)1999爱思唯尔科学有限公司。保留所有权利。
Compositional changes that may occur upon CO chemisorption on PdCu(1 1 0) single crystal alloy have been studied by means of work function change measurements using the Kelvin probe technique. Furthermore, various surfaces of this alloy with different surface compositions were investigated with respect to their reactivity in the CO oxidation applying the same technique. It was found that CO chemisorption, in the case of Cu-rich surfaces, induces the segregation of Pd to the surface. High CO pressures (10(-4)-10(-3) mbar) also cause the surface segregation of still unidentified contamination characterized by an AES signal at 180 eV. In the CO oxidation experiments the PdCu alloy showed lower reactivities compared to pure Pd, even though the outermost layer was entirely composed of Pd atoms. The reactivity was found to decrease further with increasing Cu concentrations. The lower reactivity of the PdCu alloy was attributed to the charge transfer from Pd to Cu observed in this system resulting in decreasing the adsorption enthalpy land probably the sticking coefficient) of CO on "modified" Pd of the alloy surface. (C) 1999 Elsevier Science Ltd. All rights reserved.