Controlling the catalytic bond-breaking selectivity of Ni surfaces by step blocking
Controlling the catalytic bond-breaking selectivity of Ni surfaces by step blocking
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DOI：
10.1038/nmat1311
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发表时间：
2005-02
期刊：
影响因子：
41.2
通讯作者：
R. T. Vang;K. Honkala;S. Dahl;E. K. Vestergaard;J. Schnadt;E. Lægsgaard;B. Clausen;J. Nørskov
中科院分区：
文献类型：
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作者：
R. T. Vang;K. Honkala;S. Dahl;E. K. Vestergaard;J. Schnadt;E. Lægsgaard;B. Clausen;J. Nørskov
催化表面的反应活性通常由非常活泼的低配位原子主导，如阶跃边缘位置，，，。然而，在涉及多条反应路径的反应中，关于台阶边缘对选择性的影响的知识很少。这些详细的信息可能对合理设计具有更高选择性的新催化剂非常有价值。在这里，我们从扫描隧道显微镜实验和密度泛函理论计算之间的相互作用表明，乙烯在Ni(111)面上的活化遵循比更高配位的梯形位更高的分解反应活性的趋势。对于C-C键的断裂，台阶边缘效应比对于C-H键的断裂更为明显，因此台阶对断裂键的选择性起着重要的作用。此外，我们还演示了如何通过用银封闭步骤来控制反应步骤的数量。这种纳米尺度的催化剂设计方法被用于合成一种新型的高比表面积AgNi合金催化剂，并在氢解实验中进行了测试。
The reactivity of catalytic surfaces is often dominated by very reactive low-coordinated atoms such as step-edge sites,,,,,,,,,,. However, very little knowledge exists concerning the influence of step edges on the selectivity in reactions involving multiple reaction pathways. Such detailed information could be very valuable in rational design of new catalysts with improved selectivity. Here we show, from an interplay between scanning tunnelling microscopy experiments and density functional theory calculations, that the activation of ethylene on Ni(111) follows the trend of higher reactivity for decomposition at step edges as compared with the higher-coordinated terrace sites. The step-edge effect is considerably more pronounced for the C–C bond breaking than for the C–H bond breaking, and thus steps play an important role in the bond-breaking selectivity. Furthermore, we demonstrate how the number of reactive step sites can be controlled by blocking the steps with Ag. This approach to nanoscale design of catalysts is exploited in the synthesis of a new high-surface-area AgNi alloy catalyst, which is tested in hydrogenolysis experiments.