Electronic Structure Controls Reactivity of Size-Selected Pd Clusters Adsorbed on TiO2 Surfaces
Electronic Structure Controls Reactivity of Size-Selected Pd Clusters Adsorbed on TiO2 Surfaces
复制标题
DOI：
10.1126/science.1180297
复制
发表时间：
2009-11-06
期刊：
影响因子：
56.9
通讯作者：
Anderson, Scott L.
中科院分区：
文献类型：
--
作者：
Kaden, William E.;Wu, Tianpin;Anderson, Scott L.
利用模型催化剂可以系统地研究吸附在氧化物表面上的不同尺寸的金属团簇的催化活性。我们研究了在气相中选择尺寸并沉积在金红石TiO 2（110）上的Pd簇（Pdn，n = 1，2，4，7，10，16，20和25）催化CO与O-2的程序升温反应。X射线光电子能谱表明，Pd 3D结合能随簇大小非单调变化，并且这种变化与CO氧化活性的强尺寸变化相关。考虑到终态效应，低活性与高于预期的Pd 3d结合能相关，这归因于特别稳定的价电子结构;也发生从TiO 2支撑到Pd簇的电子转移。离子散射表明，小的集群形成单层岛的表面上，并开始形成第二层发生的集群大于Pd-10。
The catalytic activity of metal clusters of different sizes adsorbed on oxide surfaces can be explored systematically by using model catalysts. We studied the temperature-programmed reaction of CO with O-2 catalyzed by Pd clusters (Pdn, for n = 1, 2, 4, 7, 10, 16, 20, and 25) that were size-selected in the gas phase and deposited on rutile TiO2(110). X-ray photoemission spectroscopy revealed that the Pd 3d binding energy varied nonmonotonically with cluster size and that the changes correlated with strong size variations in CO oxidation activity. Taking final-state effects into account, low activity was correlated with higher-than-expected Pd 3d binding energy, which is attributed to a particularly stable valence electronic structure; electron transfer from the TiO2 support to the Pd clusters also occurs. Ion scattering shows that small clusters form single-layer islands on the surface and that formation of a second layer begins to occur for clusters larger than Pd-10.