《厦门大学学报（自然科学版）》

高灵敏度低能离子散射谱在多相催化研究中的应用

郑燕萍^*,陈明树

(厦门大学化学化工学院,固体表面物理化学国家重点实验室,福建厦门 361005)

关键词：高灵敏度低能离子散射谱; 低能离子散射谱; X-射线光电子能谱; 多相催化; 表面组成; 催化剂构效关系

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

ZHENG Yanping^*,CHEN Mingshu

(State Key Laboratory of Physical Chemistry of Solid Surfaces,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China)

Keywords：high sensitivity-low energy ion scattering spectroscopy(HS-LEIS); low energy ion scattering spectroscopy(LEIS); X-ray photoemission spectroscopy(XPS); heterogeneous catalysis; surface composition; structure-activity relationshipdoi:10.6043/j.issn.0438-0479.202006022

DOI: 10.6043/j.issn.0438-0479.202006008

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参考文献

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.

引言
1 LEIS介绍
2 HS-LEIS在多相催化中的应用
3 结论与展望

图1 LEIS示意图
Fig.1 Schematic of LEIS

图2 传统LEIS(a)和QTAC100 HS-LEIS(b)的原理示意图<br/>Fig.2 Schematic of the conventional LEIS(a)and QTAC100 HS-LEIS(b)

图2 传统LEIS(a)和QTAC100 HS-LEIS(b)的原理示意图
Fig.2 Schematic of the conventional LEIS(a)and QTAC100 HS-LEIS(b)

图3 HS-LEIS装置图<br/>Fig.3 The diagram of HS-LEIS

图3 HS-LEIS装置图
Fig.3 The diagram of HS-LEIS

$图4 5%Pd/TiO2在不同温度氧化后的HS-LEIS和XPS谱图及其表面Pd原子分数(修改自文献[19])<br/>Fig.4 HS-LEIS and XPS spectra and surface atomic fraction of Pd for the oxidation of the 5%Pd/TiO2 after oxidation at various temperatures(modified from Ref.[19])$

图4 5%Pd/TiO2在不同温度氧化后的HS-LEIS和XPS谱图及其表面Pd原子分数(修改自文献[19])
Fig.4 HS-LEIS and XPS spectra and surface atomic fraction of Pd for the oxidation of the 5%Pd/TiO2 after oxidation at various temperatures(modified from Ref.[19])

图5 不同载体负载的Au催化剂的HS-LEIS谱图[20]<br/>Fig.5 HS-LEIS spectra of Au catalysts with different supports[20]

图5 不同载体负载的Au催化剂的HS-LEIS谱图[20]
Fig.5 HS-LEIS spectra of Au catalysts with different supports[20]

图6 不同还原温度下2%Au/TiO2(a)和2%Au/TS-6(b)的HS-LEIS谱图及其Au信号变化曲线(c)和催化CO氧化反应的稳定性(d)[20]<br/>Fig.6 HS-LEIS spectra for 2%Au/TiO2(a)and 2%Au/TS-6(b)after hydrogen reduction at various temperatures,the signal of Au as a function of reduction temperature(c),CO oxidation activities as a function of the reaction time(d)[20]

图6 不同还原温度下2%Au/TiO2(a)和2%Au/TS-6(b)的HS-LEIS谱图及其Au信号变化曲线(c)和催化CO氧化反应的稳定性(d)[20]
Fig.6 HS-LEIS spectra for 2%Au/TiO2(a)and 2%Au/TS-6(b)after hydrogen reduction at various temperatures,the signal of Au as a function of reduction temperature(c),CO oxidation activities as a function of the reaction time(d)[20]

图7 500 ℃氢气预还原后5%Pd0.97Au/TiO2在各氧化温度下的HS-LEIS谱图(a)及其Pd-3d(b)和Au-4f(c)的XPS谱图和由XPS和HS-LEIS计算得出的表面Pd/Au原子比的变化趋势(d)(修改自文献[19])<br/>Fig.7 HS-LEIS spectra(a)and XPS spectra of Pd-3d(b)and Au-4f(c)for the 5%Pd0.97Au/TiO2 prereduced of H2 at 500 ℃ and then oxidized at various temperatures,and atomic ratio of Pd/Au of surface evaluated from the XPS and HS-LEIS peak area(d)(modified from Ref.[19])

图7 500 ℃氢气预还原后5%Pd0.97Au/TiO2在各氧化温度下的HS-LEIS谱图(a)及其Pd-3d(b)和Au-4f(c)的XPS谱图和由XPS和HS-LEIS计算得出的表面Pd/Au原子比的变化趋势(d)(修改自文献[19])
Fig.7 HS-LEIS spectra(a)and XPS spectra of Pd-3d(b)and Au-4f(c)for the 5%Pd0.97Au/TiO2 prereduced of H2 at 500 ℃ and then oxidized at various temperatures,and atomic ratio of Pd/Au of surface evaluated from the XPS and HS-LEIS peak area(d)(modified from Ref.[19])

图8 5%Pd6.8Au/TiO2的HS-LEIS(20Ne+)谱图(a)及其表面Pd/Au原子比随着溅射深度的变化(b)[19]<br/>Fig.8 HS-LEIS(20Ne+)spectra of 5%Pd6.8Au/TiO2(a)and variation of Pd/Au atomic ratio on 5%Pd6.8Au/TiO2surface with sputtering depth(b)[19]

图8 5%Pd6.8Au/TiO2的HS-LEIS(20Ne+)谱图(a)及其表面Pd/Au原子比随着溅射深度的变化(b)[19]
Fig.8 HS-LEIS(20Ne+)spectra of 5%Pd6.8Au/TiO2(a)and variation of Pd/Au atomic ratio on 5%Pd6.8Au/TiO2surface with sputtering depth(b)[19]

图9 根据HS-LEIS计算出的5%Pd0.97Au/TiO2表面Pd/Au原子比随着H2还原温度的变化[19]<br/>Fig.9 Atomic ratio of Pd/Au as a function of the reduction temperature for the 5%Pd0.97Au/TiO2,which reduced by H2 and characterized by HS-LEIS[19]

图9 根据HS-LEIS计算出的5%Pd0.97Au/TiO2表面Pd/Au原子比随着H2还原温度的变化[19]
Fig.9 Atomic ratio of Pd/Au as a function of the reduction temperature for the 5%Pd0.97Au/TiO2,which reduced by H2 and characterized by HS-LEIS[19]

图10 分别经过450 ℃氧化和500 ℃还原后,TiO2负载和非负载PdxAuy催化剂表面-体相Pd/(Pd+Au)原子比(HS-LEIS)的变化相图[19]<br/>Fig.10 Phase diagrams of surface atomic ratio of Pd/(Pd+Au)(HS-LEIS)as a function of the bulk value for both supported and unsupported PdxAuy catalysts after oxidation at 450 ℃ and reduction at 500 ℃[19]

图10 分别经过450 ℃氧化和500 ℃还原后,TiO2负载和非负载PdxAuy催化剂表面-体相Pd/(Pd+Au)原子比(HS-LEIS)的变化相图[19]
Fig.10 Phase diagrams of surface atomic ratio of Pd/(Pd+Au)(HS-LEIS)as a function of the bulk value for both supported and unsupported PdxAuy catalysts after oxidation at 450 ℃ and reduction at 500 ℃[19]

图11 不同预处理后5%Pd0.97Au/TiO2(a)和500 ℃预还原后不同组成的5%PdxAuy/TiO2(b)催化CO氧化的活性,以及90 ℃时不同成5%PdxAuy/TiO2催化CO反应的TOF对最表层Pd/(Pd+Au)原子比作图(c)[19]<br/>Fig.11 Oxidation activity of CO catalyzed by 5%Pd0.97Au/TiO2 under different pretreatment(a)and 5%PdxAuy/TiO2 which prereduced under 500 ℃(b), CO TOF as a function of the surface atomic ratio of Pd/(Au+Pd)for 5%PdxAuy/TiO2 react at 90 ℃(c[19]

图11 不同预处理后5%Pd0.97Au/TiO2(a)和500 ℃预还原后不同组成的5%PdxAuy/TiO2(b)催化CO氧化的活性,以及90 ℃时不同成5%PdxAuy/TiO2催化CO反应的TOF对最表层Pd/(Pd+Au)原子比作图(c)[19]
Fig.11 Oxidation activity of CO catalyzed by 5%Pd0.97Au/TiO2 under different pretreatment(a)and 5%PdxAuy/TiO2 which prereduced under 500 ℃(b), CO TOF as a function of the surface atomic ratio of Pd/(Au+Pd)for 5%PdxAuy/TiO2 react at 90 ℃(c[19]

图12 PtCux/TiO2催化剂(a)和PtCux催化剂(b)的表面-体相组成相图[35]<br/>Fig.12 Phase diagrams of the surface composition versus the bulk composition for PtCux/TiO2 catalyst(a),and PtCux catalyst(b)[35]

图12 PtCux/TiO2催化剂(a)和PtCux催化剂(b)的表面-体相组成相图[35]
Fig.12 Phase diagrams of the surface composition versus the bulk composition for PtCux/TiO2 catalyst(a),and PtCux catalyst(b)[35]

图13 Pt-Fe(OH)x/TiO2(a)和Pt-FeNi(OH)x/TiO2(b)的HS-LEIS谱图[39]<br/>Fig.13 HS-LEIS spectra of the Pt-Fe(OH)x/TiO2(a)and Pt-FeNi(OH)x/TiO2(b)[39]

图13 Pt-Fe(OH)x/TiO2(a)和Pt-FeNi(OH)x/TiO2(b)的HS-LEIS谱图[39]
Fig.13 HS-LEIS spectra of the Pt-Fe(OH)x/TiO2(a)and Pt-FeNi(OH)x/TiO2(b)[39]

图14 Pt/C和Pt@h-BN/C-700催化剂的HS-LEIS谱图[41]<br/>Fig.14 HS-LEIS spectra of Pt/C and Pt@h-BN/C-700 catalysts[41]

图14 Pt/C和Pt@h-BN/C-700催化剂的HS-LEIS谱图[41]
Fig.14 HS-LEIS spectra of Pt/C and Pt@h-BN/C-700 catalysts[41]

图15 PtRu/C和PtRu@h-BN/C 催化剂的HS-LEIS谱图(a),PtRu@h-BN/C催化剂的HRTEM图(b)、XPS N-1s(c)和B-1s(d)谱图[42]<br/>Fig.15 HS-LEIS spectra of the PtRu/C and PtRu@h-BN/C catalysts(a), HRTEM images(b), XPS N-1s(c)and B-1s(d)spectra of the PtRu@h-BN/C catalyst[42]

图15 PtRu/C和PtRu@h-BN/C 催化剂的HS-LEIS谱图(a),PtRu@h-BN/C催化剂的HRTEM图(b)、XPS N-1s(c)和B-1s(d)谱图[42]
Fig.15 HS-LEIS spectra of the PtRu/C and PtRu@h-BN/C catalysts(a), HRTEM images(b), XPS N-1s(c)and B-1s(d)spectra of the PtRu@h-BN/C catalyst[42]

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《厦门大学学报（自然科学版）》于1931年创刊，是由教育部主管，厦门大学主办，国内外公开发行的综合性学术期刊（双月刊），是我国自然科学核心期刊。本刊以印刷版、网络版的方式同时出版。主要刊载自然科学各学科的最新研究成果，包括自然科学基础理论研究、应用基础研究、高新技术方面的学术论文。所刊载的论文分三大类型：（1）“快讯”：报道某前沿领域具有突破性的最新研究成果。（2）“研究论文”：刊载理工科基础理论研究与实验研究学术论文。（3）“研究简报”：刊载内容新颖、实用（或阶段性）的成果。更多>>

备注

引言

1 LEIS介绍

2 HS-LEIS在多相催化中的应用

3 结论与展望

学报简介