Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce2Zr2Ox Catalyst Particles by Nano‐XAFS

Ishiguro, Nozomu; Uruga, Tomoya; Sekizawa, Oki; Tsuji, Takuya; Suzuki, Motohiro; Kawamura, N.; Mizumaki, Masaichiro; Nitta, Kiyofumi; Yokoyama, Toshihiko; Tada, Mizuki

doi:10.1002/cphc.201400090

Cited by 31 publications

(23 citation statements)

References 45 publications

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“…[9] Oxygen composition was estimated by linear combination fitting of the Ce L III -edge nano-XANES spectra of pyrochlore Ce 2 Zr 2 O 7 and k-phase Ce 2 Zr 2 O 8 . X-rays from an undulator were monochromatized by Si(111) crystals and focused by Kirkpatrick-Baez mirrors to as ize of 409 (h) 154 (v) nm (6 keV).…”

Section: Methodsmentioning

confidence: 99%

“…[8] We previously reported the spatial distribution of Ce oxidation states in individual particles of Pt/CZ catalysts by spatially resolved scanning nano-XAFS. [9] Ex situ nano-XAFS analysis revealed differences in Ce oxidation states in individual Pt/CZ particles with different oxygen contents. However,t he size of Pt nanoparticles on CZ surfaces (< 10 nm) was much smaller than the size of probe X-ray beams (> 100 nm), and details regarding oxygen diffusion from the interface of the Pt catalyst into the CZ bulk were not reported because of alack of spatial information about the Pt nanoparticles on CZ support.…”

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confidence: 98%

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Imaging of Oxygen Diffusion in Individual Platinum/Ce₂Zr₂O_x Catalyst Particles During Oxygen Storage and Release

et al. 2016

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The spatial distribution of Ce 3+ and Ce 4+ in each particle of Ce 2 Zr 2 O x in athree-wayconversion catalyst system was successfully imaged during an oxygen storage/release cycle by scanning X-ray absorption fine structure (XAFS) using hardX-raynanobeams.For the first time,nano-XAFS imaging visualizeda nd identified the modes of non-uniform oxygen diffusion from the interface of Pt catalyst and Ce 2 Zr 2 O x support and the active parts in individual catalyst particles.Heterogeneous solid catalysts are utilized for various chemical processes and are intrinsically non-uniform with respect to structure.S olid catalysts are typically in powder form, which is an assembly of non-uniform particles with different structural components (morphology,s urface structure,d omain boundary,o xygen content, and so forth). [1] In practice,the reactivity of asolid catalyst is evaluated based on the average of these structural components,and as aresult it remains difficult to understand the real variation of the active parts in ah eterogeneous catalyst. To solve this problem, spatially resolved imaging of chemical states in an individual catalyst particle is highly sought to reveal the active parts and non-uniform reaction modes at the nanoscale.Ce is ak ey element for the oxygen storage/release function in at hree-way catalyst system for clean-up of gaseous automobile exhaust;aredox process between Ce 3+ and Ce 4+ controls oxygen content in these catalyst systems. [2] However,itiswell-known that only Ce species with extensive surface defects can contribute to the redox process in pure ceria, which offers insufficient oxygen storage/release capacity.C e 2 Zr 2 O x (CZ; x = 7-8) solid-solution crystal contains an ordered arrangement of Ce and Zr atoms and exhibits excellent oxygen storage/release properties. [3] Almost 90 %ofthe Ce atoms in CZ bulk can participate in the redox

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Section: Methodsmentioning

confidence: 99%

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confidence: 98%

Imaging of Oxygen Diffusion in Individual Platinum/Ce₂Zr₂O_x Catalyst Particles During Oxygen Storage and Release

et al. 2016

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“…In this paper, the new ESRF ID16B-NA Nanoanalysis beamline was applied for the rst time for XRF imaging with a resolution level down to a few tens of nanometres on rare geological materials: meteoritic fragments from achondrite NWA 6693 and diamond inclusions. Ishiguro et al 398 visualised the heterogeneity of Ce oxidation states in single Pt/Ce 2 Zr 2 O x catalyst particles by nano-XAFS using an X-ray nanobeam. It was discovered that the track of bubble-like inclusions in NWA 6693 consisted mainly of Cr-rich phases, although some inclusions containing Ni and Ca were also detected.…”

Section: Thin Lms Coatings and Nanomaterialsmentioning

confidence: 99%

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

West¹,

Ellis

Potts

et al. 2015

J. Anal. At. Spectrom.

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“…Conversely, if we zoom in on the nanoparticles by using TEM we can obtain a precise determination of individual supported nanoparticle dimensions and distributions if a representative sample of the powder is investigated . Besides electron microscopy, a wide variety of X‐ray‐based imaging techniques have been developed to study the heterogeneity of solid catalysts …”

Section: Introductionmentioning

confidence: 99%

Origin and Abatement of Heterogeneity at the Support Granule Scale of Silver on Silica Catalysts

et al. 2017

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Incipient wetness impregnation is used commonly to form supported metal nanoparticle catalysts. Recently, it has been revealed that this approach may induce severe heterogeneity between catalyst granules of the same batch. At least a 10‐fold variation in metal loading was observed, which affect the catalytic performance of individual catalyst granules severely. However, the origin of this heterogeneity is still unclear. Here we show that every elementary step in the preparation procedure of a Ag on silica catalyst has an effect on the resulting interparticle heterogeneity, but the influence of the drying step is the most important. This is because drying by capillary force results in a heterogeneous sample. Specifically, the position of a granule in the stagnant drying bed influences the resulting color and, thus, Ag loading significantly. This is further demonstrated by varying the drying conditions: freeze‐drying and fluidized‐bed drying led to a more homogeneous Ag loading. An investigation of the fluidized‐bed‐dried sample by using optical microscopy revealed a large fraction of transparent granules (94 %), which indicates that almost all the Ag nanoparticles in this sample are confined within the 6 nm pores. The optimized supported Ag on silica catalyst shows a good catalytic performance. This adaptation of the drying step can be implemented easily on a laboratory scale, is scalable, and does not require the use of expensive solvents or metal precursors.

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Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce₂Zr₂O_x Catalyst Particles by Nano‐XAFS

Cited by 31 publications

References 45 publications

Imaging of Oxygen Diffusion in Individual Platinum/Ce₂Zr₂O_x Catalyst Particles During Oxygen Storage and Release

Imaging of Oxygen Diffusion in Individual Platinum/Ce₂Zr₂O_x Catalyst Particles During Oxygen Storage and Release

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

Origin and Abatement of Heterogeneity at the Support Granule Scale of Silver on Silica Catalysts

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Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce2Zr2Ox Catalyst Particles by Nano‐XAFS

Cited by 31 publications

References 45 publications

Imaging of Oxygen Diffusion in Individual Platinum/Ce2Zr2Ox Catalyst Particles During Oxygen Storage and Release

Imaging of Oxygen Diffusion in Individual Platinum/Ce2Zr2Ox Catalyst Particles During Oxygen Storage and Release

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

Origin and Abatement of Heterogeneity at the Support Granule Scale of Silver on Silica Catalysts

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Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce₂Zr₂O_x Catalyst Particles by Nano‐XAFS

Imaging of Oxygen Diffusion in Individual Platinum/Ce₂Zr₂O_x Catalyst Particles During Oxygen Storage and Release

Imaging of Oxygen Diffusion in Individual Platinum/Ce₂Zr₂O_x Catalyst Particles During Oxygen Storage and Release