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

Journal Article · Thu Oct 24 00:00:00 EDT 2019 · ACS Catalysis

DOI:https://doi.org/10.1021/acscatal.9b03113· OSTI ID:1706629

Li, Junhao ^[1]; Liu, Zhongqi  ^[1]; Cullen, David A.  ^[2]; Hu, Wenhui ^[3]; Huang, Jier  ^[3]; Yao, Libo ^[4]; Peng, Zhenmeng  ^[4]; Liao, Peilin ^[5]; Wang, Ruigang  ^[1]

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1. Univ. of Alabama, Tuscaloosa, AL (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
3. Marquette Univ., Milwaukee, WI (United States)
4. Univ. of Akron, OH (United States)
5. Purdue Univ., West Lafayette, IN (United States)

Here, 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.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); American Chemical Society Petroleum Research Fund
• Grant/Contract Number: AC05-00OR22725; CHE-1657943; CBET-1856729
• OSTI ID: 1706629
• Journal Information: ACS Catalysis, Vol. 9, Issue 12; ISSN 2155-5435
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
RuOx/CeO2 catalyst
morphology effects
reduction treatment
oxygen storage capacity
CO oxidation