Reaction-Driven Restructuring of Rh-Pd and Pt-Pd Core-Shell Nanoparticles

Feng, Tao; Graß, Michael; Zhang, Yawen; Butcher, Derek R.; Renzas, Russ; Liu, Zhi; Chung, Jen Yang; Mun, Bongjin Simon; Salmerón, Miquel; Somorjai, Gábor A.

doi:10.1126/science.1164170

Cited by 1,192 publications

(1,088 citation statements)

References 13 publications

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“…8,9 We find that only core−shell NPs with compositions near 50% Rh have the core−shell reversal induced by O-coverage due to NP geometric size effect, agreeing with observation. 9 The simulated shell concentration of Rh in the small Pd 0.5 Rh 0.5 NP across the same effective O-coverage range also agrees with the experimental data on large NPs, reflecting the same origin from the relative strength of metal−O to metal−metal interactions.…”

supporting

confidence: 88%

Configurational Thermodynamics of Alloyed Nanoparticles with Adsorbates

2014

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Changes in the chemical configuration of alloyed nanoparticle (NP) catalysts induced by adsorbates under working conditions, such as reversal in core-shell preference, are crucial to understand and design NP functionality. We extend the cluster expansion method to predict the configurational thermodynamics of alloyed NPs with adsorbates based on density functional theory data. Exemplified with PdRh NPs having Ocoverage up to a monolayer, we fully detail the core-shell behavior across the entire range of NP composition and O-coverage with quantitative agreement to in situ experimental data. Optimally fitted cluster interactions in the heterogeneous system are the key to enable quantitative Monte Carlo simulations and design. ABSTRACT: Changes in the chemical configuration of alloyed nanoparticle (NP) catalysts induced by adsorbates under working conditions, such as reversal in core−shell preference, are crucial to understand and design NP functionality. We extend the cluster expansion method to predict the configurational thermodynamics of alloyed NPs with adsorbates based on density functional theory data. Exemplified with PdRh NPs having O-coverage up to a monolayer, we fully detail the core−shell behavior across the entire range of NP composition and O-coverage with quantitative agreement to in situ experimental data. Optimally fitted cluster interactions in the heterogeneous system are the key to enable quantitative Monte Carlo simulations and design.

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confidence: 88%

Configurational Thermodynamics of Alloyed Nanoparticles with Adsorbates

2014

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“…Likewise, bimetallic systems might show segregation of one metal on the surface depending on the reaction conditions (Figure 4 e), which might lead to formation of core–shell structures as in the case of PdRh nanoparticles that show Rh segregation during NO oxidation 52. Another example is the intermetallic compound Pd 2 Ga for selective hydrogenations for which surface decomposition induced by oxygen impurities yields a Ga‐depleted Pd phase and Ga 2 O 3 as active phases of the catalyst 53.…”

Section: Snapshots On Working Catalysts: Case Studies Unravelling Stmentioning

confidence: 99%

Future Challenges in Heterogeneous Catalysis: Understanding Catalysts under Dynamic Reaction Conditions

et al. 2016

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In the future, (electro‐)chemical catalysts will have to be more tolerant towards a varying supply of energy and raw materials. This is mainly due to the fluctuating nature of renewable energies. For example, power‐to‐chemical processes require a shift from steady‐state operation towards operation under dynamic reaction conditions. This brings along a number of demands for the design of both catalysts and reactors, because it is well‐known that the structure of catalysts is very dynamic. However, in‐depth studies of catalysts and catalytic reactors under such transient conditions have only started recently. This requires studies and advances in the fields of 1) operando spectroscopy including time‐resolved methods, 2) theory with predictive quality, 3) kinetic modelling, 4) design of catalysts by appropriate preparation concepts, and 5) novel/modular reactor designs. An intensive exchange between these scientific disciplines will enable a substantial gain of fundamental knowledge which is urgently required. This concept article highlights recent developments, challenges, and future directions for understanding catalysts under dynamic reaction conditions.

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“…It has been shown that intermetallic compounds could maintain their surface structure under reaction conditions, 10 whereas the surface composition and structure of alloys usually change under different reaction environments. 11 Combined, these two features, unique electronic structure and high stability, potentially circumvent problems with traditional, supported multimetal/alloy catalysts, such as chemical heterogeneity of particles (which is detrimental to selectivity), broad distributions of active sites, surface segregation, and the formation of carbides or hydrides.…”

Section: * S Supporting Informationmentioning

confidence: 99%

Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

Xiao¹,

Wang

Maligal‐Ganesh³

et al. 2013

J. Am. Chem. Soc.

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The enhanced stability and modified electronic structure of intermetallic compounds provide discovery of superior catalysts for chemical conversions with high activity, selectivity, and stability. We find that the intermetallic NaAu 2 is an active catalyst for CO oxidation at low temperatures. From density functional theory calculations, a reaction mechanism is suggested to explain the observed low reaction barrier of CO oxidation by NaAu 2 , in which a CO molecule reacts directly with an adsorbed O 2 to form an OOCO* intermediate. The presence of surface Na increases the binding energy of O 2 and decreases the energy barrier of the transition states. KeywordsMaterials Science and Engineering, Ames Laboratory, chemical conversions, enhanced stability, heterogeneous catalyst, low temperatures, reaction barriers, reaction mechanism, superior catalysts, electronic structure, gold, oxygen, sodium, alloy, carbon monoxide ABSTRACT: The enhanced stability and modified electronic structure of intermetallic compounds provide discovery of superior catalysts for chemical conversions with high activity, selectivity, and stability. We find that the intermetallic NaAu 2 is an active catalyst for CO oxidation at low temperatures. From density functional theory calculations, a reaction mechanism is suggested to explain the observed low reaction barrier of CO oxidation by NaAu 2 , in which a CO molecule reacts directly with an adsorbed O 2 to form an OOCO* intermediate. The presence of surface Na increases the binding energy of O 2 and decreases the energy barrier of the transition states.

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Reaction-Driven Restructuring of Rh-Pd and Pt-Pd Core-Shell Nanoparticles

Abstract: The structure and composition of core-shell Rh 0.5

Cited by 1,192 publications

References 13 publications

Configurational Thermodynamics of Alloyed Nanoparticles with Adsorbates

Configurational Thermodynamics of Alloyed Nanoparticles with Adsorbates

Future Challenges in Heterogeneous Catalysis: Understanding Catalysts under Dynamic Reaction Conditions

Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

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Reaction-Driven Restructuring of Rh-Pd and Pt-Pd Core-Shell Nanoparticles

Abstract: The structure and composition of core-shell Rh 0.5

Cited by 1,192 publications

References 13 publications

Configurational Thermodynamics of Alloyed Nanoparticles with Adsorbates

Configurational Thermodynamics of Alloyed Nanoparticles with Adsorbates

Future Challenges in Heterogeneous Catalysis: Understanding Catalysts under Dynamic Reaction Conditions

Intermetallic NaAu2 as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

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Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation