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Study on surface chemical reactions by real-time tracing with atomic-resolution microscope and x-ray spectroscopy

原子分辨率显微镜和X射线光谱实时追踪研究表面化学反应

基本信息

批准号：
17205002
负责人：
KONDOH Hiroshi
金额：
$ 30.78万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

The aim of this project is developing a combined approach of spatial distribution of surface species obtained from microscopic techniques and kinetics information provided from synchrotron-based spectroscopies and reaction simulations to understand the mechanisms of surface reactions proceeding on solid surfaces and its application to mechanistic studies on actual surface reactions. The mechanistic studies on the basis of this approach revealed the microscopic mechanisms for several important surface processes as shown below and led to confirm its usefulness.1. CO oxidation Pt(111), which is a model reaction for the automobile catalysis, exhibits a significant decrease in reaction rate when surface oxygen atoms form two-dimensional islands. It was clarified that this rate reduction is caused by strong destabilization of the transition state for oxidation of CO molecules inside the islands due to large repulsive interactions with neighbor CO molecules.2. For NO reduction on Rh(111), which is a model reaction for the automobile catalysis, we found a new reaction path where impinging NO molecules from gas phase form a NO dimer and react with surface nitrogen. It was revealed that attack of the NO dimer to surface nitrogen with N-N bond facing to the surface plays a key role in this reaction.3. Proton transfer at surfaces, which is considered to act an important role on the Pt fuel-cell catalysts, was studied using H_2O+OH overlayers on Pt(111). As a result, we found not only the simple proton transfer from H_2O to OH but also significant contribution of proton transfer via formation of H_3O+ to the next-nearest OH site. We also estimated the time scale of the two proton transfer processes for the first time.

该项目的目的是开发一种结合微观技术获得的表面物种的空间分布和基于同步加速器的光谱学和反应模拟提供的动力学信息的方法，以了解固体表面上进行的表面反应的机理及其在实际表面反应的机理研究中的应用。基于这种方法的机理研究揭示了如下所示的几个重要表面过程的微观机理，并证实了其有用性。CO氧化Pt（111）是汽车催化的模型反应，当表面氧原子形成二维岛时，反应速率显著降低。有人澄清，这种速率降低是由于强烈的不稳定的过渡态氧化的CO分子内部的岛屿，由于大的排斥相互作用与相邻的CO分子。对于汽车催化剂的模型反应--Rh（111）表面的NO还原反应，我们发现了一条新的反应途径，即气相中的NO分子碰撞形成NO二聚体并与表面氮反应。结果表明，NO二聚体以N-N键面向表面的方式进攻表面氮在该反应中起着关键作用.利用Pt（111）表面的H_2O+OH覆盖层研究了质子在Pt燃料电池催化剂表面的转移。结果表明，不仅存在简单的质子从H_2O到OH的转移，而且还存在通过形成H_3O ~+到次近邻OH位的质子转移。我们还首次估计了这两个质子转移过程的时间尺度。