Distribution and Valence State of Ru Species on CeO2 Supports: Support Shape Effect and Its Influence on CO Oxidation,ACS Catalysis

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Distribution and Valence State of Ru Species on CeO2 Supports: Support Shape Effect and Its Influence on CO Oxidation
ACS Catalysis ( IF 11.3 ) Pub Date : 2019-11-07 , DOI: 10.1021/acscatal.9b03113
Junhao Li ₁ , Zhongqi Liu ₁ , David A. Cullen ₂ , Wenhui Hu ₃ , Jier Huang ₃ , Libo Yao ₄ , Zhenmeng Peng ₄ , Peilin Liao ₅ , Ruigang Wang ₁

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In this work, ruthenium (Ru) catalysts supported on CeO₂ nanorods (NR), nanocubes (NC), and nanoctahedra (NO) were comparatively investigated to correlate the shape and exposed surface planes ({100}, {110}, and {111}) of nanoscale CeO₂ supports with their low-temperature CO oxidation activity. Within the 5Ru/CeO₂-r catalysts with three morphologies after reduction treatment, the Ru supported on CeO₂ NR exhibited enhanced low-temperature (<100 °C) hydrogen consumption and superior room-temperature CO oxidation activity (∼9% CO conversion). Both X-ray photoelectron spectroscopy and X-ray absorption spectroscopy measurements revealed that Ruⁿ⁺ homogeneously predominates the 5Ru/CeO₂NR-r, which is very different from partial metallic Ru⁰ supported on CeO₂ NC and NO, indicating the strong metal–support interaction formation between Ru and CeO₂ NR by Ru ions diffusing into CeO₂ surface lattice or forming Ru–O–Ce bonds at the interface. The enriched surface defects on the exposed {111} planes of CeO₂ NR support are believed to be the key to the formation of cationic Ru species, which is of vital importance for the superior room-temperature CO oxidation activity of the 5Ru/CeO₂NR-r catalyst. The higher surface oxygen vacancy concentration on 5Ru/CeO₂NR-r than those on the CeO₂ NC and NO is also crucial for adsorption/dissociation of oxygen in achieving low-temperature CO oxidation activity.

中文翻译：

CeO ₂载体上Ru物种的分布和价态：载体形状效应及其对CO氧化的影响

在这项工作中，对负载在CeO ₂纳米棒（NR），纳米立方体（NC）和纳米八面体（NO）上的钌（Ru）催化剂进行了比较研究，以将形状和暴露的表面平面相关联（{100}，{110}和{ 111}）纳米CeO ₂载体具有低温CO氧化活性。在还原处理后具有三种形态的5Ru / CeO ₂ -r催化剂中，负载在CeO ₂ NR上的Ru表现出增强的低温（<100°C）氢消耗量和优异的室温CO氧化活性（〜9％CO转化率））。X射线光电子能谱和X射线吸收能谱测量均显示Ru ^{n +}均匀地占5Ru / CeO _2的主导地位。NR-r与负载在CeO ₂ NC和NO上的部分金属Ru ⁰有很大不同，表明Ru离子扩散到CeO ₂表面晶格或形成Ru–O–时，Ru和CeO ₂ NR之间形成了强烈的金属-载体相互作用。铈在界面处键合。人们认为CeO ₂ NR载体的暴露的{111}面上富集的表面缺陷是形成阳离子Ru物种的关键，这对于5Ru / CeO ₂的出色的室温CO氧化活性至关重要。NR-r催化剂。上5RU /铈较高的表面氧空位浓度₂ NR-R比上的CeO ₂ NC和NO对于实现低温CO氧化活性，对于氧的吸附/离解也至关重要。

更新日期：2019-11-08

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