Active Nonmetallic Au and Pt Species on Ceria-Based Water-Gas Shift Catalysts

Fu, Qi; Saltsburg, Howard; Flytzani‐Stephanopoulos, Maria

doi:10.1126/science.1085721

Cited by 2,807 publications

(2,381 citation statements)

References 18 publications

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“…1,2,3,4,5 The key point at the basis of its catalytic activity is the low energy cost for the formation of oxygen vacancies and Ce 3+ centers. Since these chemical species are extremely catalytically active, a huge amount of studies have focused on the strategies to maximize their amount, stability and organization.…”

Section: Introductionmentioning

confidence: 99%

TiO₂@CeO_x Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

Artiglia

Agnoli

Paganini

et al. 2014

ACS Appl. Mater. Interfaces

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The Ce 4+ ↔ Ce 3+ redox switch is at the basis of an all-inorganic catalytic cycle that is capable to mimic the activity of several natural redox enzymes. The efficiency of these artificial enzymes (nanozymes) strongly depends on the Ce 4+ /Ce 3+ ratio. By capitalizing on the results obtained on oxide/oxide model systems, we implemented a simple and effective procedure to obtain conformal TiO 2 @CeO x core-shell nanoparticles whose thickness is controlled with single layer precision. Since the Ce 3+ species are stabilized only at the interface by the electronic hybridization with the TiO 2 states, the modulation of the shell thickness offers a simple method to tailor the Ce 4+ /Ce 3+ ratio and therefore the catalytic properties. The activity of these nanoparticles as artificial peroxidase-like enzymes was tested, showing exceptional 2 performances, even better than natural horseradish peroxidase enzyme. The main advantage with respect to other oxide/oxide nanozymes is that our nanoparticles, having a tunable Ce 4+ /Ce 3+ ratio, are efficient already at low H 2 O 2 concentrations.

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Section: Introductionmentioning

confidence: 99%

TiO₂@CeO_x Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

Artiglia

Agnoli

Paganini

et al. 2014

ACS Appl. Mater. Interfaces

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“…6 The formation of the Pt 5 Ce alloy was also detected by Bernal et al for Pt/CeO 2 samples reduced at 1173 K. 7 The hypothesis that the real catalytic site results from the interaction of platinum with the support surface found experimental evidence in the work of Fu et al, who observed that Pt supported on ceria continued to be active for the water gas-shift reaction also after leaching the metal phase by CN -and concluded that the catalytic sites are constituted by Pt 2+ and Pt 4+ species atomically dispersed in the oxide matrix. 10 The possibility that some kind of strong metal-support interaction (SMSI) is operative in TWCs and affects the catalytic properties was put forth by different authors, 2,3,[11][12][13] although there is not a general agreement about the beneficial or detrimental effect of such an interaction. Aiming at a structural characterization of the metal-support interface, we carried out in situ XAS experiments on the Pt L III edge of a Pt/ceria-zirconia catalyst.…”

Section: Introductionmentioning

confidence: 99%

Metal−Support Interaction and Redox Behavior of Pt(1 wt %)/Ce_0.6Zr_0.4O₂

Deganello¹,

Giannici²,

Martorana³

et al. 2006

J. Phys. Chem. B

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The catalyst Pt(1 wt %)/Ce 0.6 Zr 0.4 O 2 is studied by CO-temperature programmed reduction (CO-TPR), isothermal oxygen storage complete capacity (OSCC), X-ray absorption spectroscopy (XAS) at the Pt L III edge, and in situ X-ray diffraction (in situ XRD), with the aim of elucidating the role of supported metal in CO oxidation by ceria-based three-way catalysts (TWC). The redox behavior of Pt(1 wt %)/Ce 0.6 Zr 0.4 O 2 is compared to that of bare ceria-zirconia. OSCC of redox-aged Pt/ceria-zirconia is twice that of bare ceria-zirconia, and the maximum of CO consumption occurs at a temperature about 300 K lower than redox-aged ceria-zirconia. XAS analysis allows one to evidence the formation of a platinum-cerium alloy in redox-aged samples and the stability of the metal particles toward oxidation and sintering during high-temperature treatments. Under CO flux at 773 K, bare ceria-zirconia shows a continuous drift of diffraction peaks toward smaller Bragg angles, due to a progressive increase of Ce(III) content. Under the same treatment, the structural rearrangement of Pt-supported ceria-zirconia starts after an induction time and takes place with an abrupt change of the lattice constant. The experimental evidence points to the role of supported Pt in modifying the redox properties of ceria-zirconia with respect to the bare support. It is proposed that the much faster bulk reduction observed by in situ XRD for redox-aged Pt/ceria-zirconia can be attributed to an easier release of reacted CO 2 , producing a more effective turnover of reactants at the catalyst surface.

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“…Cerium oxide (CeO 2 ) is a semiconductor with wide band gap energy (3.19eV). In the recent years, much effort has been made towards the development of new synthetic routes for preparing nanostructure cerium oxides due to their potential uses in many applications, such as high-storage capacitor devices, buffer layers for conductors, fuel cells, polishing materials, UV blocks and optical devices [1][2][3][4][5][6][7] . The cerium oxide nanoparticles are prepared by various methods [8][9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Structural, Optical, Morphological and Dielectric Properties of Cerium Oxide Nanoparticles

Prabaharan¹,

Sadaiyandi

Mahendran³

et al. 2016

Mat. Res.

149

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Cerium oxide (CeO 2 ) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature.

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Active Nonmetallic Au and Pt Species on Ceria-Based Water-Gas Shift Catalysts

Cited by 2,807 publications

References 18 publications

TiO₂@CeO_x Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

TiO₂@CeO_x Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

Metal−Support Interaction and Redox Behavior of Pt(1 wt %)/Ce_0.6Zr_0.4O₂

Structural, Optical, Morphological and Dielectric Properties of Cerium Oxide Nanoparticles

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Active Nonmetallic Au and Pt Species on Ceria-Based Water-Gas Shift Catalysts

Cited by 2,807 publications

References 18 publications

TiO2@CeOx Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

TiO2@CeOx Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

Metal−Support Interaction and Redox Behavior of Pt(1 wt %)/Ce0.6Zr0.4O2

Structural, Optical, Morphological and Dielectric Properties of Cerium Oxide Nanoparticles

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Product

Resources

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TiO₂@CeO_x Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

TiO₂@CeO_x Core–Shell Nanoparticles as Artificial Enzymes with Peroxidase-Like Activity

Metal−Support Interaction and Redox Behavior of Pt(1 wt %)/Ce_0.6Zr_0.4O₂