Abstract

Palladium (Pd/CeO₂), gold (Au/CeO₂), and bimetallic (PdAu/CeO₂) nanoparticles obtained via impregnation of the surface of cerium dioxide with tetraethylene pentamine and subsequent reduction in a H₂/Ar flow are synthesized and described. The particles possess a high degree of dispersion, but their small size complicates their analysis with conventional methods (transmission electron microscopy and X-ray powder diffraction). Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with CO sample molecules is used to study the size and morphology of the nanoparticles and the substrate. The intensity ratios of the bands assigned to bridge and linear carbonyls at palladium centers indicate that there are finely divided nanoparticles in the case of a monometallic sample and larger nanoparticles in the case of a bimetallic one. The resulting materials have high catalytic activity and stability: the complete conversion of CO for Pd/CeO₂ is achieved at about 50°C. We find that the catalytic activity of the samples decreases in the series Pd/CeO₂–Au/CeO₂–PdAu/CeO₂, which indicates that there is no synergistic effect in the case of a bimetallic sample.

中文翻译：

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CeO 2基底上金和钯纳米小颗粒的合成与描述：FT-IR光谱数据

摘要

钯（Pd / CeO ₂），金（Au / CeO ₂）和双金属（PdAu / CeO ₂）纳米粒子是通过用四亚乙基五胺浸渍二氧化铈表面并随后还原H _{2而获得的}合成/ Ar流。颗粒具有较高的分散度，但是其尺寸小，使其与常规方法（透射电子显微镜和X射线粉末衍射）的分析复杂化。漫反射红外傅里叶变换光谱（DRIFTS）与CO样品分子的结合用于研究纳米粒子和基质的尺寸和形态。在钯中心分配给桥羰基和线性羰基的谱带的强度比表明，在单金属样品的情况下存在细碎的纳米颗粒，在双金属样品的情况下存在较大的纳米颗粒。所得材料具有高催化活性和稳定性：CO完全转化为Pd / CeO ₂在约50℃下达到。我们发现，样品的催化活性在Pd / CeO ₂ -Au / CeO ₂ -PdAu / CeO ₂系列中降低，这表明在双金属样品的情况下没有协同作用。