CO oxidation catalysed by Pd-based bimetallic nanoalloys.
CO oxidation catalysed by Pd-based bimetallic nanoalloys.
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DOI：
10.1039/c5cp00889a
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发表时间：
2015-02
期刊：
影响因子：
--
通讯作者：
D. Palagin;J. Doye
中科院分区：
文献类型：
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作者：
D. Palagin;J. Doye
基于密度泛函理论的全局几何优化，证明了催化簇的几何形状对钯基双金属纳米合金CO氧化反应的能垒的重要影响。我们表明，反应中间体之间剧烈的几何变化可以导致非常高的能量势垒，从而对整个过程是禁止的。这给新催化剂的设计和所采用的理论方法都带来了挑战。在理论方面，仔细选择所有反应中间体的几何构型对于充分描述可能的反应路径至关重要。从催化剂设计的角度来看，可以通过调整簇与掺杂金属之间的相互作用水平来控制簇的几何形状，也可以通过在单个纳米合金颗粒中混合不同的金属来调节吸附分子与催化剂簇之间的相互作用水平。我们发现，用单个Ag原子取代Pd5簇中的Pd原子形成Pd4Ag1，可能会改善簇对CO氧化反应的催化性能。另一方面，单个Au原子不会增强催化剂的性能，这是由于簇的组成金属和吸附分子之间的杂化较弱。双金属纳米合金团簇的这种性质的灵活性说明了微调的可能性，这可能用于设计新的高效催化材料。
Density functional theory based global geometry optimization has been used to demonstrate the crucial influence of the geometry of the catalytic cluster on the energy barriers for the CO oxidation reaction over Pd-based bimetallic nanoalloys. We show that dramatic geometry change between the reaction intermediates can lead to very high energy barriers and thus be prohibitive for the whole process. This introduces challenges for both the design of new catalysts, and theoretical methods employed. On the theory side, a careful choice of geometric configurations of all reaction intermediates is crucial for an adequate description of a possible reaction path. From the point of view of the catalyst design, the cluster geometry can be controlled by adjusting the level of interaction between the cluster and the dopant metal, as well as between the adsorbate molecules and the catalyst cluster by mixing different metals in a single nanoalloy particle. We show that substitution of a Pd atom in the Pd5 cluster with a single Ag atom to form Pd4Ag1 leads to a potential improvement of the catalytic properties of the cluster for the CO oxidation reaction. On the other hand, a single Au atom does not enhance the properties of the catalyst, which is attributed to a weaker hybridization between the cluster's constituent metals and the adsorbate molecules. Such flexibility of properties of bimetallic nanoalloy clusters illustrates the possibility of fine-tuning, which might be used for design of novel efficient catalytic materials.