Shape-dependent interplay between oxygen vacancies and Ag-CeO2 interaction in Ag/CeO2 catalysts and their influence on the catalytic activity

被引：327

作者：

Chang, Sujie ^{[1
,2
,3
]}

Li, Mo ^{[1
]}

Hua, Qing ^{[1
,2
,3
]}

Zhang, Lijuan ^{[4
]}

Ma, Yunsheng ^{[1
]}

Ye, Bangjiao ^{[4
]}

Huang, Weixin ^{[1
,2
,3
]}

机构：

[1] Univ Sci & Technol China, Dept Chem Phys, Hefei 230026, Peoples R China

[2] Univ Sci & Technol China, CAS Key Lab Mat Energy Convers, Hefei 230026, Peoples R China

[3] Univ Sci & Technol China, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Peoples R China

[4] Univ Sci & Technol China, Dept Modern Phys, Hefei 230026, Peoples R China

来源：

JOURNAL OF CATALYSIS | 2012年 / 293卷

基金：

中国国家自然科学基金;

关键词：

Ag/CeO2; catalysts; CO oxidation; Active structure; Metal-support interaction; Oxygen vacancy; Shape dependence; SELECTIVE SYNTHESIS; CEO2; NANOCRYSTALS; OXIDATION-STATE; CO OXIDATION; CERIA; SURFACE; NANOCOMPOSITES; REDUCIBILITY; NANORODS; DEFECTS;

D O I：

10.1016/j.jcat.2012.06.025

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070305 [高分子化学与物理];

摘要：

Ag/CeO2 catalysts employing CeO2 nanocubes (c-CeO2) and nanorods (r-CeO2) as the support were prepared by conventional incipient wetness impregnation followed by calcination at 500 degrees C in air. Their structures have been characterized in detail and their catalytic activities in CO oxidation have also been tested. c-CeO2 and r-CeO2 nanocrystals exhibit different concentrations and structures of oxygen vacancies. The silver-r-CeO2 interaction is stronger than the silver-c-CeO2 interaction. Fine Ag nanoparticles form in 1%-Ag/c-CeO2 and grow in size in 3%-Ag/c-CeO2; however, positively charged Ag-n(+) clusters dominate in 1%-Ag/r-CeO2, and fine Ag nanoparticles dominate in 3%-Ag/r-CeO2. Supported Ag nanoparticles are much more capable of creating oxygen vacancies in CeO2 than supported positively charged Ag-n(+) clusters. More oxygen vacancies form in Ag/c-CeO2 than in Ag/r-CeO2. The average charge density of oxygen vacancies and the ratio between large oxygen vacancy clusters and small vacancies in CeO2 nanocrystals are enhanced when loaded with positively charged Ag-n(+) clusters but reduced when loaded with Ag nanoparticles. Ag nanoparticles greatly promote the reduction and catalytic activity in CO oxidation of CeO2 nanocrystals but positively charged Ag-n(+) clusters do not. These results demonstrate the concept that the interplay between oxygen vacancies and Ag-CeO2 interaction controls the structures of silver and CeO2 in Ag/CeO2 catalysts and thus their surface reactivity and catalytic activity, deepening the fundamental understanding of metal/CeO2 catalysts. These results also reveal that the interplay between oxygen vacancies and Ag-CeO2 interaction in Ag/CeO2 catalysts depends on the shape of CeO2 support, opening up a new strategy for the design of efficient and economic metal/CeO2 catalysts by engineering the shape of CeO2 support. (C) 2012 Elsevier Inc. All rights reserved.

引用

页码：195 / 204

页数：10

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