Study on Catalytic and Electronic Properties of Deposited Alloy Clusters onto a Substrate

基底上沉积合金团簇的催化和电子性能研究

基本信息

批准号：
13640582
负责人：
NAKAJIMA Atsushi
金额：
$ 2.43万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

This study has been focused on adsorption reactivity and electronic property of alloy clusters as a microscopic model of catalytic activity, because finite system of metal/alloy clusters having 2-100 atoms can be regarded as a minimum catalytic site. A couple of binary clusters were chosen in the viewpoint of useful catalytic activity ; (a) alloy clusters of niobium (Nb)-aluminum (Al), gold (Au)-palladium (Pd), and gold (Au)-zinc (Zn), (b) semiconductor clusters of lanthanide/transition-metal-silicon (Si), and (c) metal oxides of vanadium oxide and cobalt oxide. Furthermore, the soft-landing technique was successfully established to design catalytic surface with the deposition of alloy clusters synthesized in gas phase.The binary clusters were generated by the two-rod laser vaporization, and their electronic properties were studied with photoelectron spectroscopy. The results summarized as follows ; (a) Adsorption reactivity of the alloy clusters was correlated well with geometries rather than electronic structures. In Au-Pd clusters, interestingly, an electron promotion occurs from 4d to 5s orbital in the Pd atom. (b) In semiconductor binary clusters, adsorption reactivity provides the information on reaction sites, and metal-encapsulated silicon clusters were discovered. (c) In metal oxide clusters, geometric phase transition was drastically induced by the mixing of oxygen atoms into metal clusters, although oxygen atoms having less than 10% concentration could be treated as impurity atoms. Photoelectron spectroscopy and mass spectrometry for reactivity have revealed fundamental insight on composite effects in alloy/binary clusters, of which the principles can lead to design new catalyst with the soft-landing technique.

这项研究集中在合金簇作为催化活性的微观模型上的吸附反应性和电子特性上，因为具有2-100个原子的金属/合金簇的有限系统可以视为最小催化位点。在有用的催化活性的角度选择了几个二元簇。（a）尼伯（NB） - 铝（AL），金（AU） - 甲基（PD）和黄金（AU）-ZINC（Zn），（B）半导体的半导体簇/过渡 - 过渡金属硅硅（SI）和（C）金属氧化物的金属氧化物和COBALT OXIDIDE的合金簇。此外，通过在气相中合成的合金簇的沉积，成功建立了软地面技术来设计催化表面。二进制簇是由两杆激光蒸发产生的，并通过光电子光谱学研究了它们的电子性能。结果总结如下；（a）合金簇的吸附反应性与几何形状而不是电子结构良好相关。有趣的是，在AU-PD簇中，PD原子中的4D到5s轨道发生电子促进。（b）在半导体二进制簇中，吸附反应性提供了反应位点的信息，并发现了金属已封装的硅簇。（C）在金属氧化物簇中，通过将氧原子混合到金属簇中的几何相变为巨大诱导，尽管氧原子的浓度少于10％可以被视为杂质原子。用于反应性的光电子光谱和质谱法揭示了对合金/二元簇中复合效应的基本见解，其原理可以通过软地面技术导致设计新的催化剂。