Converting nanocrystalline metals into alloys and intermetallic compounds for applications in catalysis
Converting nanocrystalline metals into alloys and intermetallic compounds for applications in catalysis
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DOI：
10.1039/b712035d
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发表时间：
2008-01-01
影响因子：
--
通讯作者：
Schaak, Raymond E.
中科院分区：
文献类型：
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作者：
Bauer, J. Chris;Chen, Xiaole;Schaak, Raymond E.
多金属纳米颗粒，特别是合金和金属间化合物，是各种化学转化的有用催化剂。负载型金属间纳米颗粒催化剂通常是通过将前驱体沉积在载体上，然后进行高温退火来制备的，这是生成金属间化合物所必需的，但会导致烧结并使表面积最小化。本研究表明，将金属纳米颗粒转化为金属间化合物的溶液化学方法适用于负载型纳米颗粒催化剂体系。通过与适当的金属盐溶液在还原条件下反应，可将未负载的纳米晶Pt转化为纳米晶PtSn、PtPb、PtBi和FePt3。类似的反应将Al2O3， CeO2和碳负载的Pt纳米颗粒转化为PtSn， PtPb, PtSb， Pt3Sn和Cu3Pt。这些反应直接在溶液中产生支撑合金和金属间纳米颗粒，而不需要高温退火或额外的表面稳定剂。这些金属间纳米颗粒对甲酸氧化（PtPb/Vulcan）和CO氧化（Pt3Sn/石墨）等化学转化具有催化活性。值得注意的是，PtPb/Vulcan XC-72电催化氧化甲酸的电位（0.1 V）低于商用PtRu/Vulcan XC-72 （0.4 V）。
Multi-metal nanoparticles, particularly alloys and intermetallic compounds, are useful catalysts for a variety of chemical transformations. Supported intermetallic nanoparticle catalysts are usually prepared by depositing precursors onto a support followed by high-temperature annealing, which is necessary to generate the intermetallic compound but causes sintering and minimizes surface area. Here we show that solution chemistry methods for converting metal nanoparticles into intermetallic compounds are applicable to supported nanoparticle catalyst systems. Unsupported nanocrystalline Pt can be converted to nanocrystalline PtSn, PtPb, PtBi, and FePt3 by reaction with appropriate metal salt solutions under reducing conditions. Similar reactions convert Al2O3, CeO2, and carbon-supported Pt nanoparticles into PtSn, PtPb, PtSb, Pt3Sn, and Cu3Pt. These reactions generate supported alloy and intermetallic nanoparticles directly in solution without the need for high temperature annealing or additional surface stabilizers. These supported intermetallic nanoparticles are catalytically active for chemical transformations such as formic acid oxidation (PtPb/Vulcan) and CO oxidation (Pt3Sn/graphite). Notably, PtPb/Vulcan XC-72 was found to electrocatalytically oxidize formic acid at a lower onset potential (0.1 V) than commercial PtRu/Vulcan XC-72 (0.4 V).