Thermally induced sintering and redispersion of Au nanoparticles supported on Ce1-xEuxO2 nanocubes and their influence on catalytic CO oxidation

Bezkrovnyi, Oleksii; Kraszkiewicz, Piotr; Krivtsov, Igor; Quesada, Jorge; Ordóñez, Salvador; Kępiński, Leszek

doi:10.1016/j.catcom.2019.105798

Cited by 11 publications

(27 citation statements)

References 37 publications

(42 reference statements)

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“…Both samples were pretreated in air at 300 °C for 3 hthe necessary step to clean their surface from −OH, −CO 3 , and −NO 3 groups. 19 In previous study, we showed that XRD patterns of Ce 1−x Eu x O 2 and Au/Ce 1−x Eu x O 2 (x = 0 and 0.20) samples contain reflections from fluorite-type ceria only. Au related reflections for Au/CeO 2 , Au/Ce 0.80 Eu 0.20 O 2 samples (treated at 300 °C for 3 h in air) were not detected due to the low Au content (∼1 at.…”

Section: ■ Experimental Partmentioning

confidence: 99%

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NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce_1–xEu_xO₂ Nanocubes

et al. 2020

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Control of metal–support interactions is one of the major challenges in heterogeneous catalysis. In this study, we explored the effect of Eu doping on the metal–support interactions in Au/Ce1–x Eu x O2 catalysts applied in the oxidation of CO. We probe the catalysts with CO under realistic conditions by near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). NAP-XPS allows in situ investigation of the surface reducibility of the ceria support and charging of the Au nanoparticles. Both parameters are crucial, as they are responsible for the efficiency of Au/ceria catalysts in the CO oxidation. We found that doping of the ceria support with Eu decreases the reducibility of Ce4+ in the Au/Ce1–x Eu x O2 system and the population of Auδ+ sites. We identified the available CO adsorption sites on Au/ceria (Auδ−, Au0, and Auδ+) in the typical temperature window of the CO oxidation reaction by in situ DRIFTS. We found that the difference in the catalytic activity of Au/CeO2 and Au/Ce0.80Eu0.20O2 does not origin from an electronic effect of the Eu dopant or different adsorption sites but from the size of the Au nanoparticles. The most active Au nanoparticles are very small, reactive Au nanoparticles, which are exclusively present on the undoped ceria support.

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Section: ■ Experimental Partmentioning

confidence: 99%

“…Our previous results showed that the catalyst samples become active toward the CO oxidation in this temperature range. 19 No CO adsorption was found on the pristine CeO 2 and Ce 0.8 Eu 0.2 O 2 supports (see Figure S5), which confirms that all signals indeed originate from CO adsorption on Au.…”

Section: ■ Experimental Partmentioning

confidence: 99%

NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce_1–xEu_xO₂ Nanocubes

et al. 2020

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“…It remains an open question about the presence/absence of highly active subnanometer Au clusters in these samples. However, we observed the presence of such Au clusters in Au/CeO 2 (NC) annealed at 300 °C [32,33]. There are no objective reasons which can prevent thermally induced redispersion (e.g., strong anchoring on oxygen vacancies) in all investigated samples (annealed in the air only).…”

Section: Co Proxmentioning

confidence: 71%

“…It can be explained by the presence of highly active sub-nanometer Au nanoclusters in pre-treated samples (both at 300 and 500 °C). In our previous works, we observed, using (S)TEM technique, such Au clusters in Au/ CeO 2 (NC) annealed at 300 °C [32,33]. The second possible explanation is the presence of pseudo-single sites, i.e., gold ions slightly abstracted from a gold clusters, which exhibit lower activation energy in the rate-determining step of COoxidation [34].…”

Section: Co-oxidationmentioning

confidence: 87%

The Sintering of Au Nanoparticles on Flat {100}, {111} and Zigzagged {111}-Nanofacetted Structures of Ceria and Its Influence on Catalytic Activity in CO Oxidation and CO PROX

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The thermal stability of Au nanoparticles on ceria support of various morphology (nanocubes, nanooctahedra, and {111}-nanofacetted nanocubes) in oxidizing and reducing atmospheres was investigated by electron microscopy. A beneficial effect of the reconstruction of edges of ceria nanocubes into zigzagged {111}-nanofacetted structures on the inhibition of sintering of Au nanoparticles was shown. The influence of different morphology of Au particles on various ceria supports on the reducibility and catalytic activity in CO oxidation, and CO PROX of Au/ceria catalysts was also investigated and discussed. It was shown, that ceria nanocubes with flat {110} terminated edges are more suitable as a support for Au nanoparticles, used to catalyze CO oxidation, than zigzagged {111}- nanofacetted structures. Graphic Abstract

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“…show that the cerium oxide with a cube‐like morphology is a good support for the nanocrystalline gold. However, in the study presented in, only large cube‐like CeO 2 crystals were taken into consideration. In the present work, we have been taken to answer the following question – Why the gold nanoparticles are invisible in Au/CeO 2 (small cube‐like) sample?…”

Section: Resultsmentioning

confidence: 99%

Decoration of Cube‐Like Ceria Crystals by Well‐Dispersed Au Nanoparticles: Surface Influence

2020

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In this paper, the run of the decorating process of the active support, like CeO2, by the gold nanoparticles via deposition‐precipitation method has been studied. Two types of the Au/CeO2 systems with different mean particle size (but the same morphology) of the support have been investigated. It was noted that the decoration process proceeds easily only for large crystals with average size about 67 nm. Three hypotheses were tested in order to explain unsuccessful initial Au nanoparticles decoration of the cube‐like CeO2 crystals with average size about 14 nm as a support. The tests have shown that the ratio of the molar content of the chloroauric acid to the total surface area of the support (MAu/SCeO2) has a significant impact on the decorating process of CeO2 by nano‐Au. If the above ratio is too small, the thin layer of gold instead of the Au nanoparticles is formed on the support surface. In this paper, the calculations of the real surface area (from TEM/HRTEM data) were used to adjust the optimum the MAu/SCeO2 to obtain the Au/CeO2 system with the desired properties.

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Thermally induced sintering and redispersion of Au nanoparticles supported on Ce1-xEuxO2 nanocubes and their influence on catalytic CO oxidation

Cited by 11 publications

References 37 publications

NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce_1–xEu_xO₂ Nanocubes

NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce_1–xEu_xO₂ Nanocubes

The Sintering of Au Nanoparticles on Flat {100}, {111} and Zigzagged {111}-Nanofacetted Structures of Ceria and Its Influence on Catalytic Activity in CO Oxidation and CO PROX

Decoration of Cube‐Like Ceria Crystals by Well‐Dispersed Au Nanoparticles: Surface Influence

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Thermally induced sintering and redispersion of Au nanoparticles supported on Ce1-xEuxO2 nanocubes and their influence on catalytic CO oxidation

Cited by 11 publications

References 37 publications

NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce1–xEuxO2 Nanocubes

NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce1–xEuxO2 Nanocubes

The Sintering of Au Nanoparticles on Flat {100}, {111} and Zigzagged {111}-Nanofacetted Structures of Ceria and Its Influence on Catalytic Activity in CO Oxidation and CO PROX

Decoration of Cube‐Like Ceria Crystals by Well‐Dispersed Au Nanoparticles: Surface Influence

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NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce_1–xEu_xO₂ Nanocubes

NAP-XPS and In Situ DRIFTS of the Interaction of CO with Au Nanoparticles Supported by Ce_1–xEu_xO₂ Nanocubes