Interplay between CO Disproportionation and Oxidation: On the Origin of the CO Reaction Onset on Atomic Layer Deposition-Grown Pt/ZrO<sub>2</sub> Model Catalysts

Pramhaas, Verena; Roiaz, Matteo; Bosio, Noemi; Corva, Manuel; Rameshan, Christoph; Vesselli, Erik; Grönbeck, Henrik; Rupprechter, Günther

doi:10.1021/acscatal.0c03974

Cited by 33 publications

(32 citation statements)

References 70 publications

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“…[ 158 ] Similarly, a delicate balance of carbon formation (coking) and oxidation determines CO oxidation activity of Pt/ZrO 2 , as revealed by operando NAP‐XPS/MS (and sum frequency generation (SFG)). [ 159,160 ] Along similar lines, Pd‐carbide‐like phases (Pd x C y ), with carbon remaining in the subsurface region and Pd acting as carbon “sponge” [ 108–110,114 ] were solely formed during selective hydrogenation reactions, with their abundance affecting activity. For all these examples, such complex temperature‐ and sample prehistory (hysteresis)‐dependent catalytic performance can only be observed and explained by operando studies.…”

Section: Selected Operando Methodsmentioning

confidence: 99%

“…For other in situ/operando vibrational spectroscopy of active catalyst materials we refer to the literature (e.g., Raman [77][78][79][80][81]85,[122][123][124][125]163] and SFG [159,160,[169][170][171][172] ). The same ATR setup can also be used to study solid/liquid interfaces.…”

Section: Infrared Spectroscopy (Ftir Drifts Atr)mentioning

confidence: 99%

“…However, in many cases the interpretation and verification of the obtained experimental spectra/images/patterns relies on theoretical support, for example, by simulating test structures of clusters and nanoparticles and their corresponding spectra, calculating adsorption and reaction energies or micro-kinetic modelling. [33,98,159,[199][200][201][202][203][204][205][206][207][208][209][210] Based on its important role in catalysis, DFT is explicitly mentioned here, but without any technical details (which can be found in the references). Clearly, if calculations are performed for realistic gas pressures (coverage) and temperatures, they are even more relevant for operando studies.…”

Section: Density Functional Theorymentioning

confidence: 99%

“…[183,184] The oxidation of CO on (supported) noble metals is a benchmark reaction, both for model and applied catalysis. [159,186,[279][280][281][282] In addition, CO adsorption is frequently used to characterize the accessible surface sites. [36,73,159,162,282,283] It is well-accepted that particle size and shape and the metal/support interface govern the catalytic performance in many cases.…”

Section: Mesoscopic Pd and Rh Particles Supported By Zro 2 : Imaging Kinetic Transitions And Long-range Interface Effects On Individual Pmentioning

confidence: 99%

“…[159,186,[279][280][281][282] In addition, CO adsorption is frequently used to characterize the accessible surface sites. [36,73,159,162,282,283] It is well-accepted that particle size and shape and the metal/support interface govern the catalytic performance in many cases. Sites at metal/ oxide interface (colored light blue in Figure 1c), termed perimeter (adlineation) sites or (triple) phase boundary sites, are often even considered to be most active.…”

Section: Mesoscopic Pd and Rh Particles Supported By Zro 2 : Imaging Kinetic Transitions And Long-range Interface Effects On Individual Pmentioning

confidence: 99%

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Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Rupprechter

2021

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described as metal dispersion (number of metal surface atoms relative to the total number of metal atoms in the catalyst), whereas the support is characterized by the specific surface area (m 2 g −1). For hemispherical metal particles of ≈1.5, 2, 5, and 10 nm diameter, the dispersion is about 0.8, 0.6, 0.3, and 0.1, respectively, illustrating why the nanoscale is required not to waste precious metal inside the particles. The ultimate dispersion is, of course, provided by single metal atoms and this concept is followed in "single atom catalysis" or "single site catalysis". [10-17] However, the adsorption and reaction steps of a catalytic reaction do typically not occur on isolated single atoms, but also involve neighboring sites, for example, of the oxide support [18] or of a metal matrix (for bimetallic nanoparticles, active metal atoms may be embedded in an inert or less-active metal matrix [11,19-23]). The so-called site isolation of active atoms may prevent CC bond cleavage (coking), which requires at least two neighboring active metals. In any case, the stability of the single atoms is the key challenge, as atoms may diffuse and sinter. Furthermore, for example, Pt, Pd, Cu, or Au atoms are mobilized by CO, [24-28] forming CO-M 1 units that may eventually sinter into larger clusters. Herein, we define metal clusters as entities with less than ≈100 atoms, characterizing the so-called "non-scalable" regime (Figure 1a). [29] Their atomic and electronic structure is significantly different from that of bulk metals, for example, with respect to atom positions (icosahedral vs face centered cubic fcc), distances (lattice contraction or expansion), and band structure (semiconductor vs metal). Clearly, these properties are size-dependent ("each atom counts" [30,31]), with pronounced impact on adsorption and reaction properties. [5,32] Accordingly, nanoparticles with more than ≈100 atoms are in the "scalableregime" and start to have or exhibit bulk atomic and electronic structure. [6,32-34] Nevertheless, the relative contributions of corner, edge, step, terrace and phase boundary sites on the surface of a nanoparticle (Figure 1b,c) are still size-dependent. [35,36] Meso-scale ("black") powders of metals are clearly bulk-like and have very low dispersion (Figure 1d), but the µm-sized aggregates still consist of adjoining nanocrystals with structured surfaces, comparable to that of true nanoparticles. Operando characterization of working catalysts, requiring per definitionem the simultaneous measurement of catalytic performance, is crucial to identify the relevant catalyst structure, composition and adsorbed species. Frequently applied operando techniques are discussed, including X-ray absorption spectroscopy, near ambient pressure X-ray photoelectron spectroscopy and infrared spectroscopy. In contrast to these area-averaging spectroscopies, operando surface microscopy by photoemission electron microscopy delivers spatially-resolved data, directly visualizing catalyst heterogeneity. For thorough interpretation, the exper...

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Section: Selected Operando Methodsmentioning

confidence: 99%

Section: Infrared Spectroscopy (Ftir Drifts Atr)mentioning

confidence: 99%

Section: Density Functional Theorymentioning

confidence: 99%

Section: Mesoscopic Pd and Rh Particles Supported By Zro 2 : Imaging Kinetic Transitions And Long-range Interface Effects On Individual Pmentioning

confidence: 99%

Section: Mesoscopic Pd and Rh Particles Supported By Zro 2 : Imaging Kinetic Transitions And Long-range Interface Effects On Individual Pmentioning

confidence: 99%

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Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Rupprechter

2021

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Stabilization of Exposed Metal Nanocrystals in High‐Temperature Heterogeneous Catalysis

Zhu

Feng

et al. 2021

Advanced Materials

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Colloidal metal nanocrystals with uniform sizes, shapes, compositions, and architectures are ideal building blocks for constructing heterogeneous catalysts with well‐defined characteristics toward the investigation of accurate structure–property relationships and better understanding of catalytic mechanism. However, their applications in high‐temperature heterogeneous catalysis are often restricted by the difficulty in maintaining the high metal dispersity and easy accessibility to active sites under harsh operating conditions. Here, a partial‐oxide‐coating strategy is proposed to stabilize metal nanocrystals against sintering and meanwhile enable an effective exposure of active sites. As a proof‐of‐concept, controlled partial silica coating of colloidally prepared Pd0.82Ni0.18 nanocrystals with the size of 8 nm is demonstrated. This partially coated catalyst exhibits excellent activity, selectivity, and stability, outperforming its counterparts with fully coated and supported structures, in reverse water gas shift (RWGS) catalysis particularly at high operating temperatures. This study opens a new avenue for the exploration of colloidal metal nanocrystals in high‐temperature heterogeneous catalysis.

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Operando Spectroscopy Unveils the Catalytic Role of Different Palladium Oxidation States in CO Oxidation on Pd/CeO₂ Catalysts

et al. 2022

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Aiming at knowledge‐driven design of novel metal–ceria catalysts for automotive exhaust abatement, current efforts mostly pertain to the synthesis and understanding of well‐defined systems. In contrast, technical catalysts are often heterogeneous in their metal speciation. Here, we unveiled rich structural dynamics of a conventional impregnated Pd/CeO2 catalyst during CO oxidation. In situ X‐ray photoelectron spectroscopy and operando X‐ray absorption spectroscopy revealed the presence of metallic and oxidic Pd states during the reaction. Using transient operando infrared spectroscopy, we probed the nature and reactivity of the surface intermediates involved in CO oxidation. We found that while low‐temperature activity is associated with sub‐oxidized and interfacial Pd sites, the reaction at elevated temperatures involves metallic Pd. These results highlight the utility of the multi‐technique operando approach for establishing structure–activity relationships of technical catalysts.

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Interplay between CO Disproportionation and Oxidation: On the Origin of the CO Reaction Onset on Atomic Layer Deposition-Grown Pt/ZrO₂ Model Catalysts

Cited by 33 publications

References 70 publications

Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Stabilization of Exposed Metal Nanocrystals in High‐Temperature Heterogeneous Catalysis

Operando Spectroscopy Unveils the Catalytic Role of Different Palladium Oxidation States in CO Oxidation on Pd/CeO₂ Catalysts

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Interplay between CO Disproportionation and Oxidation: On the Origin of the CO Reaction Onset on Atomic Layer Deposition-Grown Pt/ZrO2 Model Catalysts

Cited by 33 publications

References 70 publications

Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Stabilization of Exposed Metal Nanocrystals in High‐Temperature Heterogeneous Catalysis

Operando Spectroscopy Unveils the Catalytic Role of Different Palladium Oxidation States in CO Oxidation on Pd/CeO2 Catalysts

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Interplay between CO Disproportionation and Oxidation: On the Origin of the CO Reaction Onset on Atomic Layer Deposition-Grown Pt/ZrO₂ Model Catalysts

Operando Spectroscopy Unveils the Catalytic Role of Different Palladium Oxidation States in CO Oxidation on Pd/CeO₂ Catalysts