Calle-Vallejo Federico, Pohl Marcus D, Reinisch David, Loffreda David, Sautet Philippe, Bandarenka Aliaksandr S
Leiden Institute of Chemistry , Leiden University , PO Box 9502 , 2300 RA Leiden , The Netherlands . Email:
Physik-Department ECS , Technische Universität München , James-Franck-Str. 1 , D-85748 Garching , Germany . Email:
Chem Sci. 2017 Mar 1;8(3):2283-2289. doi: 10.1039/c6sc04788b. Epub 2016 Dec 6.
Experiments on model surfaces commonly help in identifying the structural sensitivity of catalytic reactions. Nevertheless, their conclusions do not frequently lead to devising superior "real-world" catalysts. For instance, this is true for single-crystal platinum electrodes and the oxygen reduction reaction (ORR), an important reaction for sustainable energy conversion. Pt(111) is substantially enhanced by steps, reaching a maximum at short terrace lengths of 3-4 atoms. Conversely, regular platinum nanoparticles with similar undercoordinated defects are less active than Pt(111) and their activity increases alongside the terrace-to-defect ratio. We show here that a model to design ORR active sites on extended surfaces can also be used to solve this apparent contradiction and provide accurate design rules for nanoparticles. Essentially, only surfaces and nanostructures with concave defects can surpass the activity of Pt(111), whereas convex defects are inactive. Importantly, only the latter are present in regular nanoparticles, which is why we design various concave nanoparticles with high activities.
在模型表面上进行的实验通常有助于确定催化反应的结构敏感性。然而，这些实验得出的结论并不常常能促成设计出更优的“实际应用”催化剂。例如，单晶铂电极和氧还原反应（ORR）就是如此，氧还原反应是可持续能源转换中的一个重要反应。台阶显著增强了Pt(111)的活性，在3 - 4个原子的短平台长度时达到最大值。相反，具有类似低配位缺陷的规则铂纳米颗粒的活性低于Pt(111)，并且它们的活性随着平台与缺陷的比例增加而提高。我们在此表明，一种用于设计扩展表面上ORR活性位点的模型也可用于解决这一明显的矛盾，并为纳米颗粒提供精确的设计规则。从本质上讲，只有具有凹形缺陷的表面和纳米结构才能超越Pt(111)的活性，而凸形缺陷则无活性。重要的是，规则纳米颗粒中仅存在后者，这就是我们设计各种具有高活性的凹形纳米颗粒的原因。
