Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States.
Langmuir. 2013 May 21;29(20):6025-31. doi: 10.1021/la400005d. Epub 2013 May 9.
The morphology and surface elemental composition of Au-Pd bimetallic nanoclusters are reported to be sensitive to and affected by reduced silicon defect sites and structural corrugation on SiO2/Si(100), generated by argon ion sputtering under ultrahigh vacuum (UHV) conditions. Metastable structures of the bimetallic clusters, where Au atoms are depleted from the top surface upon annealing, are stabilized by the interaction with the reduced silica sites, as indicated from CO temperature programmed desorption (TPD) titration measurements. Acetylene conversion to ethylene and benzene has been studied as a probe reaction, revealing the modification of selectivity and reactivity enhancement in addition to improved thermal stability on substrates rich in reduced-silica sites. These observations suggest that these unique sites play an important role in anchoring thermodynamically metastable conformations of supported Au-Pd bimetallic catalysts and dictate their high-temperature activity.
报道称，金钯双金属纳米团簇的形态和表面元素组成对 SiO2/Si(100)上的硅缺陷位和结构波纹（在超高真空 (UHV) 条件下通过氩离子溅射产生）敏感，并受其影响。从 CO 程序升温脱附 (TPD) 滴定测量可知，双金属团簇的亚稳结构中，退火时金原子从表面耗尽，与还原的硅位点相互作用稳定下来。我们选择乙炔转化为乙烯和苯作为探针反应进行研究，结果表明，除了提高热稳定性之外，在富含还原硅位点的衬底上还可以提高选择性和反应活性。这些观察结果表明，这些独特的位点在锚定负载金钯双金属催化剂的热力学亚稳构象方面发挥着重要作用，并决定了它们的高温活性。
