Reversible precipitation/dissolution of precious-metal clusters in perovskite-based catalyst materials: Bulk versus surface re-dispersion

Katz, Michael B.; Zhang, Shuyi; Duan, Yulong; Wang, Hongjie; Fang, Minghao; Zhang, Kui; Li, Baihai; Graham, George W.; Pan, Xiaoqing

doi:10.1016/j.jcat.2012.06.017

Cited by 98 publications

(108 citation statements)

References 10 publications

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“…At least, the partial embedding of these particles in the support surface confirms that they strongly interact with the host structure ( Figure 7) [78]. In fact, contrary to what happens during the relatively long pretreatment procedure prior to HAADF-STEM observation (1 h under constant atmosphere [79] or alternance between reducing and oxidizing environments every 10 min [78]), one can expect that this interaction should be constantly revived under the high frequency (0.5-5 Hz) redox fluctuations of a real exhaust. This should limit the mobility of the precious metal particles on the surface of the host material and prevent their agglomeration.…”

Section: Incorporation Of a Noble Metalmentioning

confidence: 79%

“…The formation and dissolution of noble metal clusters at the surface of the perovskite particles was found to be much more limited than expected [78]. The surface noble metal clusters formed after reduction in 10 vol% H 2 /N 2 at 800 °C for 1 h tended to coarsen rather than return into the perovskite matrix after oxidation in 20 vol% O 2 /N 2 at 800 °C for 1 h [79]. At least, the partial embedding of these particles in the support surface confirms that they strongly interact with the host structure ( Figure 7) [78].…”

Section: Incorporation Of a Noble Metalmentioning

confidence: 82%

“…The stronger metal-support interaction of the noble metal with a perovskite-type oxide support, as compared to a conventional alumina support, significantly increases its resistance to thermal sintering, allowing to enhance the catalytic performance while minimizing the noble metal content [76,77]. Recent HAADF-STEM observations on Pd-LaFeO 3 , Pt-CaTiO 3 , Rh-CaTiO 3 , and Pt-BaCeO 3 systems question the self-regenerative function [78,79]. The microscopy study evidenced that a fraction of the fully reversible formation-dissolution of noble metal particles under redox cycling predominantly takes place within the bulk of the host structure.…”

Section: Incorporation Of a Noble Metalmentioning

confidence: 99%

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Structured Perovskite-Based Catalysts and Their Application as Three-Way Catalytic Converters—A Review

et al. 2014

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Automotive Three-Way Catalysts (TWC) were introduced more than 40 years ago. Despite that, the development of a sustainable TWC still remains a critical research topic owing to the increasingly stringent emission regulations together with the price and scarcity of precious metals. Among other material classes, perovskite-type oxides are known to be valuable alternatives to conventionally used TWC compositions and have demonstrated to be suitable for a wide range of automotive applications, ranging from TWC to Diesel Oxidation Catalysts (DOC), from NO x Storage Reduction catalysts (NSR) to soot combustion catalysts. The interest in these catalysts has been revitalized in the past ten years by the introduction of the concept of catalyst regenerability of perovskite-based TWC, which is in principle well applicable to other catalytic processes as well, and by the possibility to reduce the amounts of critical elements, such as precious metals without seriously lowering the catalytic performance. The aim of this review is to show that perovskite-type oxides have the potential to fulfil the requirements (high activity, stability, and possibility to be included into structured catalysts) for implementation in TWC.

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Section: Incorporation Of a Noble Metalmentioning

confidence: 79%

Section: Incorporation Of a Noble Metalmentioning

confidence: 82%

Section: Incorporation Of a Noble Metalmentioning

confidence: 99%

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Structured Perovskite-Based Catalysts and Their Application as Three-Way Catalytic Converters—A Review

et al. 2014

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“…Particles may be re-dissolved into the host lattice on oxidation and subsequently re-exsolved upon reduction. Even though this does not appear to be universally applicable or fully reversible 100 , it may serve as proof of concept that that microstructures and interfaces may be rejuvenated by carrying out controlled redox cycles, thus improving the longevity of certain catalytic systems.…”

Section: Exsolutionmentioning

confidence: 99%

Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers

et al. 2016

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“…Moreover, in the majority of these systems, exsolutions occur preferentially within the bulk rather than on the surface, rendering most of the nano-particles inaccessible for catalysis and thus decreasing the overall effectiveness of the approach 11 . Recently we found that harder-toreduce cations can also be exsolved and, additionally, exsolutions emerge preferentially on the surface when highly A-site deficient perovskites (A/B < 1) are employed (e.g.…”

Section: Introductionmentioning

confidence: 99%

In situ growth of nanoparticles through control of non-stoichiometry

et al. 2013

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Surfaces decorated with uniformly dispersed catalytically active nanoparticles play a key role in many fields, including renewable energy and catalysis. Typically, these structures are prepared by deposition techniques, but alternatively they could be made by growing the nanoparticles in situ directly from the (porous) backbone support. Here we demonstrate that growing nano-size phases from perovskites can be controlled through judicious choice of composition, particularly by tuning deviations from the ideal ABO 3 stoichiometry. This non-stoichiometry facilitates a change in equilibrium position to make particle exsolution much more dynamic, enabling the preparation of compositionally diverse nanoparticles (that is, metallic, oxides or mixtures) and seems to afford unprecedented control over particle size, distribution and surface anchorage. The phenomenon is also shown to be influenced strongly by surface reorganization characteristics. The concept exemplified here may serve in the design and development of more sophisticated oxide materials with advanced functionality across a range of possible domains of application. AbstractSurfaces decorated with uniformly dispersed catalytically active nanoparticles play a key role in many fields including renewable energy and catalysis. These structures are typically prepared by deposition techniques, but alternatively they could be made by growing the nanoparticles in situ directly from the (porous) backbone support. Here we demonstrate that growing nano-size phases from perovskites can be controlled through judicious choice of composition, particularly by tuning deviations from the ideal ABO 3 stoichiometry. This nonstoichiometry facilitates a change in equilibrium position to make particle exsolution much more dynamic, enabling the preparation of compositionally diverse nanoparticles (i.e. metallic, oxides, or mixtures) and seems to afford unprecedented control over particle size, distribution and surface anchorage. The phenomenon is also shown to be strongly influenced 2 by surface reorganisation characteristics. The concept exemplified here may serve in the design and development of more sophisticated oxide materials with advanced functionality across a range of possible domains of application.

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Reversible precipitation/dissolution of precious-metal clusters in perovskite-based catalyst materials: Bulk versus surface re-dispersion

Cited by 98 publications

References 10 publications

Structured Perovskite-Based Catalysts and Their Application as Three-Way Catalytic Converters—A Review

Structured Perovskite-Based Catalysts and Their Application as Three-Way Catalytic Converters—A Review

Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers

In situ growth of nanoparticles through control of non-stoichiometry

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