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

Junhao Li; Zhongqi Liu; David A. Cullen; Wenhui Hu; Jier Huang; Libo Yao; Zhenmeng Peng; Peilin Liao; Ruigang Wang

doi:10.1021/acscatal.9b03113

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

Junhao Li, Zhongqi Liu, David A. Cullen, Wenhui Hu, Jier Huang, Libo Yao, Zhenmeng Peng, Peilin Liao, Ruigang Wang

Materials MicroAnalysis

Research output: Contribution to journal › Article › peer-review

201 Scopus citations

Abstract

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.

Original language	English
Pages (from-to)	11088-11103
Number of pages	16
Journal	ACS Catalysis
Volume	9
Issue number	12
DOIs	https://doi.org/10.1021/acscatal.9b03113
State	Published - Dec 6 2019

Funding

This work is supported by National Science Foundation (CHE-1657943 and CBET-1856729) and American Chemical Society Petroleum Research Fund (#52323). This project also receives partial financial support from Alabama Water Institute and Alabama Transportation Institute. The use of TEM facilities at the Central Analytical Facility at The University of Alabama is gratefully acknowledged. Aberration-corrected STEM–EDS was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Keywords

CO oxidation
RuO/CeO catalyst
morphology effect
oxygen storage capacity
reduction treatment

Access to Document

10.1021/acscatal.9b03113

Cite this

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title = "Distribution and Valence State of Ru Species on CeO2 Supports: Support Shape Effect and Its Influence on CO Oxidation",

abstract = "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.",

keywords = "CO oxidation, RuO/CeO catalyst, morphology effect, oxygen storage capacity, reduction treatment",

author = "Junhao Li and Zhongqi Liu and Cullen, {David A.} and Wenhui Hu and Jier Huang and Libo Yao and Zhenmeng Peng and Peilin Liao and Ruigang Wang",

note = "Publisher Copyright: Copyright {\textcopyright} 2019 American Chemical Society.",

year = "2019",

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doi = "10.1021/acscatal.9b03113",

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T1 - Distribution and Valence State of Ru Species on CeO2 Supports

T2 - Support Shape Effect and Its Influence on CO Oxidation

AU - Li, Junhao

AU - Liu, Zhongqi

AU - Cullen, David A.

AU - Hu, Wenhui

AU - Huang, Jier

AU - Yao, Libo

AU - Peng, Zhenmeng

AU - Liao, Peilin

AU - Wang, Ruigang

PY - 2019/12/6

Y1 - 2019/12/6

N2 - 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.

AB - 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.

KW - CO oxidation

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