电子结构控制了在TiO2表面上被吸附的大小选择的Pd集群的反应性
William E Kaden1, Tianpin Wu, William A Kunkel
1Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, UT 84112-0850, USA.
在二氧化表面上集群的催化活性取决于集群大小. 较小的集群表现出独特的电子结构,影响一氧化碳氧化效率.
科学领域:
- 材料科学 材料科学 材料科学
- 表面化学 表面化学
- 催化剂是一种催化剂.
背景情况:
- 模型催化剂对于理解金属集群在氧化物表面的催化活性至关重要.
- (Pd) 集群被吸附在二氧化 (TiO2) 表面上,作为研究尺寸依赖的催化性能的模型系统.
研究的目的:
- 系统地研究尺寸选择的集群 (Pd(n),n = 125) 在TiO2(110) 表面上对CO氧化发生的催化活性.
- 为了将观察到的催化活动与团的电子结构和表面形态相关联.
主要方法:
- 按尺寸选择的团在气相中准备好,并沉积在一个鲁TiO2 () 单晶表面上.
- 使用温度编程反应光谱学研究了CO氧化反应.
- 采用X射线光辐射光谱学 (XPS) 来分析星团的电子结构 (Pd 3d 结合能).
- 离子散射光谱学 (ISS) 用于确定表面形态和集群生长行为.
主要成果:
- 的团大小显著影响了CO氧化活性,显示了非单调的变化.
- X射线光辐射光谱学揭示了Pd 3d结合能量的非单调变化与集群大小,与活动变化相关.
- 较低的催化活性与稳定的价值电子结构有关,由较高的Pd 3d结合能表明.
- 观察到从TiO2支到Pd集群的电子转移的证据.
- 小小的团形成了单层岛屿,在大于Pd10的团中开始形成第二层.
结论:
- 集群在TiO2上的催化性能强烈依赖于它们的大小和由此产生的电子结构.
- 取决于尺寸的电子特性,包括从支物中转移电子,在调节催化活性方面发挥着关键作用.
- 在模型催化剂中理解这些尺寸-结构-活性关系,为异质催化提供了对异质催化物的基本见解.
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