Diatomic Steps in Pt(997) Surfaces Are Better Catalysts than Monatomic Steps for the CO Oxidation Reaction near Atmospheric Pressure

Balmès, Olivier; Prévot, Geoffroy; Torrelles, X.; Lundgren, Edvin; Ferrer, S.

doi:10.1021/acscatal.5b02526

Cited by 28 publications

(27 citation statements)

References 27 publications

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“…Simultaneously with the step doubling, the CO 2 production increased stepwise. Both the doubled step height and the increased reactivity can be the result of the O adsorption on steps, or, as was suggested, 97 the double steps themselves could be more reactive than monoatomic steps. A higher O 2 content lowered the temperature for the transition from single to double steps.…”

Section: Vicinal and Polycrystalline Pt Surfaces Co Adsorption And Omentioning

confidence: 83%

Surface science under reaction conditions: CO oxidation on Pt and Pd model catalysts

2017

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Platinum and palladium are frequently used as catalytic materials, for example for the oxidation of CO. This is one of the most widely studied reactions in the field of surface science. Although seemingly uncomplicated, it remains an active and interesting topic, which is partially explained by the push to conduct experiments on model systems under relevant reaction conditions. Recent developments in the surface-science methodology have allowed obtaining chemical and structural information on the active phase of model catalysts. Tools of the trade include near-ambient-pressure X-ray photoelectron spectroscopy, high-pressure scanning tunneling microscopy, high-pressure surface X-ray diffraction, and high-pressure vibrational spectroscopy. Interpretation is often aided by density functional theory in combination with thermodynamic and kinetic modeling. In this review, results for the catalytic oxidation of CO obtained by these techniques are compared. On several of the Pt and Pd surfaces, new structures develop in excess O 2 . For Pt, this requires a much larger excess of O 2 than for Pd. Most of these structures also develop in pure O 2 and are identified as (surface) oxides. A large body of evidence supports the conjecture that these oxides are more reactive than the corresponding O-covered metallic surfaces under similar conditions, although still debated in the literature. An outlook on this developing field, including directions that move away from CO oxidation towards more complex chemistry, concludes this review.

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Section: Vicinal and Polycrystalline Pt Surfaces Co Adsorption And Omentioning

confidence: 83%

Surface science under reaction conditions: CO oxidation on Pt and Pd model catalysts

2017

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“…14,15 But it is also of fundamental importance in catalytic reactions on transition metal surfaces, as shown for the CO oxidation of vicinal Pt(111), where double steps are more active than single steps. 16 In fcc surfaces vicinal to the (111) direction step-doubling is frequently linked to the presence of adsorbates or impurities that prefer to attach to microfacets with distinct orientation. [17][18][19][20][21][22][23][24] In the case of vicinal Ni(111), step-doubling is triggered by minute amounts of adsorbates, such as O 2 , 22,23 or by temperature-reversible migration of bulk C impurities.…”

Section: Introductionmentioning

confidence: 99%

Step-doubling at Vicinal Ni(111) Surfaces Investigated with a Curved Crystal

et al. 2017

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Vicinal surfaces may undergo structural transformations as a function of temperature or in the presence of adsorbates. Step-doubling, in which monatomic steps pair up forming double-atom high staircases, is the simplest example. Here we investigate the case of Ni(111) using a curved crystal surface, which allows us to explore the occurrence of step-doubling as a function of temperature and vicinal plane (miscut α and step type). We find a striking A-type ({100}-like microfacets) versus B-type ({111}-like) asymmetry towards step-doubling. The terrace-width distribution analysis performed from Scanning Tunneling Microscopy data points to elastic step interactions overcoming entropic effects at very small miscut α in A-type vicinals, as compared to B-type steps. For A-type vicinals, we elaborate the temperature/miscut phase diagram, on which we establish a critical miscut α c = 9.3 • for step-doubling to take place.

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“…[74][75][76][77] It is also observed in the active stage during the CO oxidation reaction in nearly-stoichiometric mixtures. 60 As we sketch in Figure 4c (Figure 2b). Although the increase in the oxygen ratio of the mixture may force the appearance of a tiny DS-O 1s signal in B-type surfaces (see Fig.…”

Section: Transient-o and Step Doubling At Vicinal Planesmentioning

confidence: 90%

“…37,[55][56][57][58][59] However, the high oxygen dissociation probability at steps may be ineffective due to an equally low CO oxidation rate, making it a priori unclear whether steps are beneficial for the catalytic efficiency of the surface. 55 Only a few experiments have been done on vicinal surfaces at millibar pressures, which prove the presence of structural instabilities 42,60 and volatile oxides, 52 pointing to diverse reaction mechanisms and structural/chemical interplay. The role of steps can be better rationalized through a simultaneous analysis of different surface planes, e.g., using cylindrical crystals.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Oxidation of CO on a Curved Pt(111) Surface: Simultaneous Ignition at All Facets Through a Transient CO-O Complex

García-Martínez¹,

́andez²,

Simonovi³

et al. 2020

Preprint

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We combine PLIF and NAP-XPS to investigate the CO oxidation reaction at vicinal Pt(111) surfaces in the millibar regime, using a curved sample. We find that the catalytic activation of Pt occurs in all vicinal planes simultaneously,<br>irrespectively of the reaction parameters. The systematic analysis of chemical species across the entire curved surface provides the clues for this surprising behavior. As the surface CO concentration decreases when approaching ignition, minor amounts of oxygen build up at both steps and (111) terraces. First-principles theory indicates that the latter is forming a CO-Pt-O complex that binds CO molecules to terraces strongly, leveling its adsorption energy to that of low-coordinated steps, and explaining why CO abruptly desorbs at the same temperature along the di erent crystal facets that make up the curved Pt surface.

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Diatomic Steps in Pt(997) Surfaces Are Better Catalysts than Monatomic Steps for the CO Oxidation Reaction near Atmospheric Pressure

Cited by 28 publications

References 27 publications

Surface science under reaction conditions: CO oxidation on Pt and Pd model catalysts

Surface science under reaction conditions: CO oxidation on Pt and Pd model catalysts

Step-doubling at Vicinal Ni(111) Surfaces Investigated with a Curved Crystal

Catalytic Oxidation of CO on a Curved Pt(111) Surface: Simultaneous Ignition at All Facets Through a Transient CO-O Complex

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