Silica-Encapsulated Intermetallic Nanoparticles for Highly Active and Selective Heterogeneous Catalysis
Silica-Encapsulated Intermetallic Nanoparticles for Highly Active and Selective Heterogeneous Catalysis
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DOI：
10.1021/accountsmr.1c00153
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发表时间：
2021-11-17
影响因子：
14.6
通讯作者：
Huang, Wenyu
中科院分区：
文献类型：
--
作者：
Chen, Minda;Bowers, Clifford R.;Huang, Wenyu
金属间化合物纳米颗粒（iNPs）作为高活性、高选择性的多相催化剂，近年来受到广泛关注。作为合金的一个子类，金属间化合物具有有序的晶体结构，因此具有明确的原子环境，不像合金的固溶体，其原子排列是随机的，并且局部不可预测。催化活性iNP通常含有第8-10族过渡金属作为“活性”金属。它们通常还包括不直接参与催化反应但可以显著改变活性金属行为的“非活性”金属。非活性金属组分的选择可以在整个周期表中进行。将iNP设计为具有优异性能的非均相催化剂仍然存在一些普遍挑战。在合成上，小纳米颗粒的高表面能易于它们的聚集，而最大化表面与体积比对于有效的贵金属利用是高度期望的。此外，尽管已经广泛研究了块状金属间化合物的形成，但纳米级金属间相的形成可能表现不同。例如，iNP的形成温度通常与从本体相图预测的温度显著不同。这种行为往往导致iNPs合成的进一步挑战。除了合成挑战外，证明iNPs在催化方面的性能并建立结构-性质关系也至关重要。仪器和计算技术通常有助于理解催化性质。由于金属间化合物结构的长程有序性，经常使用各种电子和X射线技术来精确地确定iNP的结构。密度泛函理论（DFT）计算中的结构建模也可以受益于这种有序结构。这些技术显著地提高了对iNP在热、电和电催化中增强的催化性质的理解。例如，糠醛氢化成糠醇是一种模型反应，其中PtSn iNP在氢化C=O而不是C=C键中显示出增强的活性和化学选择性。这种上级催化性能可以与基于仔细的仪器和计算表征的PtSn iNP的几何和电子表面结构的变化相关。此外，金属间化合物表面可以通过配体或缺陷进一步改性。虽然增加了复杂性的iNP系统，这些改性剂提供额外的控制其催化properties.In这个帐户，以封装在介孔二氧化硅的iNP为例，我们回顾了目前的策略，以开发iNP作为高性能的多相催化剂，与洞察不同的形成行为的iNP相比，散装金属间化合物材料。然后，我们强调这些iNP催化剂所应用的热和电催化反应。我们还讨论了独特的成对氢化反应与仲氢催化的iNPs。在这种反应中，iNP显示出无与伦比的潜力。我们预计，该帐户可以促进研究金属间化合物催化剂的额外兴趣，并为其应用奠定基础。
Intermetallic nanoparticles (iNPs) have been the subject of many recent reports for their demonstrated applications as highly active and selective heterogeneous catalysts. As a subclass of alloys, intermetallic compounds possess ordered crystal structures and, therefore, well-defined atomic environments, unlike the solid solution of alloys whose atomic arrangements are random and locally unpredictable. Catalytically active iNPs typically contain a group 8-10 transition metals as the "active" metals. They usually also include an "inactive" metal that does not directly participate in the catalytic reaction but can significantly modify the active metal's behavior. The choice of the inactive metal component can range across the periodic table.A few general challenges remain to design iNPs as heterogeneous catalysts with outstanding performance. Synthetically, the high surface energy of small nanopartides is prone to their aggregation, while maximizing the surface-to-volume ratios is highly desired for efficient noble metal utilization. Additionally, even though the formation of bulk intermetallic compounds has been extensively studied, the formation of intermetallic phases at the nanoscale can behave differently. For example, the formation temperatures of iNPs are often drastically different from those predicted from the bulk phase diagrams. This behavior often leads to further challenges in the synthesis of iNPs.In addition to synthetic challenges, it is also critical to demonstrate the performance of iNPs in catalysis and establish the structure- property relationships. Instrumental and computational techniques often assist the understanding of catalytic properties. Due to the long-range order of intermetallic structure, various electron and X-ray techniques are often used to precisely determine the structure of iNPs. Structural modeling in density functional theory (DFT) calculation can also benefit from such ordered structures. These techniques have siginificantly improved the understanding of enhanced catalytic properties of iNPs in thermo-, electro-, and photocatalysis. Hydrogenation of furfural to furfuryl alcohol, for example, is a model reaction where PtSn iNPs show enhanced activity and chemoselectivity in hydrogenating C=O rather than C=C bonds. This superior catalytic performance can be correlated to the change in the geometric and electronic surface structure of the PtSn iNPs based on careful instrumental and computational characterizations. Additionally, intermetallic surfaces can be further modified by ligands or defects. While adding complexity to iNP systems, these modifiers provide additional control over their catalytic properties.In this Account, taking encapsulated iNPs in mesoporous silica as an example, we review the current strategies to develop iNPs as high-performance heterogeneous catalysts, with insights on the distinct formation behavior of iNPs compared to bulk intermetallic materials. We then highlight thermo- and electro-catalysis reactions to which these iNP catalysts are applied. We also discuss the unique pairwise hydrogenation reaction with parahydrogen catalyzed by iNPs. In this reaction, iNPs show unparalleled potential. We anticipate that this Account could foster additional interests in studying intermetallic catalysts and lay the foundation for their applications.