高灵敏度低能离子散射谱在多相催化研究中的应用

Applications of high sensitivity-low energy ion scattering spectroscopy in heterogeneous catalysis

多相催化反应大多在催化剂表层发生,研究催化剂的表面组成、结构、化学态和催化性能之间的关系对于设计、优化工业催化剂具有重要意义.高灵敏度低能离子散射谱(HS-LEIS)既可测定样品(包括粉末及块状样品、导体和半导体等)最外原子层的元素组成和相对含量,又可推断催化剂的表面结构,因此被广泛应用于各类催化反应研究中.本文介绍了HS-LEIS的基本原理,并概述了其在催化研究中的一些应用,包括催化剂表面组成、表面活性位、双金属催化剂表面偏析和表面结构、核壳结构等的研究.同时还对比分析了目前在表面研究中应用广泛的X-射线光电子能谱(XPS)和HS-LEIS表征结果的差异,进一步说明HS-LEIS能够更为准确地获得催化剂表面的真实情况.

Heterogeneous catalytic reactions always take place on the surfaces of catalysts.It is critical to understand the surface properties,such as elements on the outmost surface,local structures,electronic properties,etc.,as well as changes of the surfaces induced under reaction conditions.High sensitivity-low energy ion scattering spectroscopy(HS-LEIS)is a unique technology that can not only sensitively analyze the composition and relative content of elements in the outermost atomic layer of a sample(induding powder and bulk samples,conductors and semiconductors),but also infer the surface structure of catalysts.Therefore,HS-LEIS has been widely used in various catalytic reactions.In this overview,HS-LEIS is introduced.Catalysis studies using HS-LEIS in studying the surface composition,surface segregation,dispersion of the active component,supported bimetal system,active surface species,core-shell structure,strong metal-support interaction,and catalytic active centers are discussed.The currently widely used X-ray photoemission spectroscopy(XPS)in catalyst characterization is compared with HS-LEIS,and HS-LEIS can achieve a more reliable surface composition than XPS of heterogeneous catalysts.