CO adsorption and dissociation on iron oxide supported Pt particles

Sun, Ying-Na; Qin, Zhihui; Lewandowski, Mikołaj; Shaikhutdinov, Shamil K.; Freund, Hans‐Joachim

doi:10.1016/j.susc.2009.08.022

Cited by 40 publications

(40 citation statements)

References 39 publications

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“…Nucleation and growth of Pt particles on Fe 3 O 4 (111) films have previously been studied in our laboratories by STM and TPD [6,12,13]. 111) and Pt(111) [6].…”

Section: Resultsmentioning

confidence: 99%

Promotional effect of metal encapsulation on reactivity of iron oxide supported Pt catalysts

Lewandowski

Sun

Qin

et al. 2011

Applied Catalysis A: General

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Abstract:We studied reactivity of well-defined Pt model catalysts, supported on crystalline iron oxide Fe 3 O 4 (111) films, in low temperature CO oxidation. It is shown that pre-annealing in vacuum at ~850 K suppresses CO adsorption but increases CO 2 production rate. This finding is rationalised in terms of Strong Metal-Support Interaction between Pt and iron oxide resulting in particles encapsulation by a thin FeO(111) film that catalyses CO oxidation similarly to the extended FeO(111)/Pt(111) surfaces previously studied (Sun et al. J. Catal, 266 (2009) 359). The results show that the stability and the atomic structure of the encapsulated layer under reaction conditions play a critical role in oxidation reactions over Pt catalysts supported on reducible oxides.

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“…Nucleation and growth of Pt particles on Fe 3 O 4 (111) films have previously been studied in our laboratories by STM and TPD [6,12,13]. 111) and Pt(111) [6].…”

Section: Resultsmentioning

confidence: 99%

Promotional effect of metal encapsulation on reactivity of iron oxide supported Pt catalysts

Lewandowski

Sun

Qin

et al. 2011

Applied Catalysis A: General

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“…Interestingly, the authors have subsequently shown that such an FeO overlayer on Pt can enhance CO oxidation activity [475; 478]. Sun et al [477] found that CO can dissociate on low-coordination sites on supported Pt clusters resulting in a build-up of carbon, and found that Fe from the support diffuses onto (or into) the Pt clusters above 600 K. Platinum is one of several metals investigated to catalyse PEC water splitting at α-Fe 2 O 3 surfaces (e.g. [518][519][520]).…”

Section: Platinummentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

487

463

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The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe 3 O 4 ), maghemite (γ-Fe 2 O 3 ), hematite (α-Fe 2 O 3 ), and wüstite (Fe 1-x O) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe 3 O 4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment, and because it is an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed.The best understood iron oxide surface at present is probably Fe 3 O 4 (100); the structure is known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Fe oct -O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10 Such straightforward preparation of a monophase termination is generally not the case for other iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe (0001) is the most studied hematite surface, but 2 difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe 3 O 4 (111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe 1-x O and α-Fe 2 O 3 (0001) islands was recently challenged and a new structure based on a thin film of Fe 3 O 4 (111) on α-Fe 2 O 3 (0001) was proposed. The merits of the compet...

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“…One may thus be relatively certain that Pt deposited on Al 2 O 3 or FeO x will form nanodots (i.e., discrete, droplet-like islands on the nanoscale) that remain intact, even in the presence of some surface oxidation of the noble metal or subsequent thermal sintering [23]. On the other hand, Al 2 O 3 is "wetable" for FeO x and will probably cause it to spread into a thin layer [1,2].…”

Section: Comparison Of Routes With Regard To Morphology Feo X /Pt Inmentioning

confidence: 99%

“…This measure is selective for Pt, because CO does not chemisorb on FeOx under the applied conditions, as we determined by a separate set of measurements. By measuring the specific Pt surface areas of comparable samples (i.e., at equal Fe and Pt concentrations) produced by each route, and comparing it to that of a reference sample without any Fe deposit (SPt reference), one can calculate a relative interfacial surface (SInterface), according to Equation (1). It gives the FeOx/Pt area (relative to a reference sample without FeOxSPt reference), for SPt and FeOx denotes the remaining "uncovered" Pt surface of a sample.…”

Section: Comparison Of Routes With Regard To Morphology Feo X /Pt Inmentioning

confidence: 99%

“…The activity of supported noble metal catalysts used for oxidation reactions, and notably of Pt on an Al 2 O 3 support, is known to be enhanced significantly by the addition of FeO x to the active phase [1][2][3][4][5][6]. The combined FeO x /Pt surface exposed to the reaction atmosphere offers an energetically more favorable mechanism for such reactions, resulting in increased rates when compared to a reference catalyst of supported Pt without FeO x .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the Activity Enhancing Role of Iron Oxide for Noble Metal Oxidation Catalysts: A CVD-Based Study with Differently Structured Combinations of Pt and FeOx Coatings on Al2O3

et al. 2018

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Abstract:With regard to the catalysis of oxidation reactions by noble metals, the addition of FeO x to an Al 2 O 3 -supported Pt catalyst is known to be energetically more favorable compared to only Pt. In this work, different process routes for the preparation of such Fe-promoted Pt/Al 2 O 3 catalysts via atmospheric chemical vapor deposition (CVD) in a fluidized bed were explored. Specifically, the question of whether it would be advantageous to deposit the Fe before, along with, or after the Pt was addressed, and new information was obtained about the optimum FeO x -Pt interface and mixing ratio. Vapors of Trimethyl(methylcyclopentadienyl)platinum(IV) and/or Ethyl-ferrocene were injected into the bed from the top, permitting a quasi-lossless precursor operation and a very good control of the deposited metal, and hence of the catalyst structure. Samples could be extracted from the top while CVD was ongoing to obtain time-resolved data. The catalytic activity was determined through CO oxidation. The Fe-Pt mixing ratio was then varied for the most active deposition sequence, in order to identify an activity optimum generated by the minimum amount of Pt catalyst. When compared to pure Pt/Al 2 O 3 , the optimum catalyst consistently showed superior performance even after thermal stress.

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CO adsorption and dissociation on iron oxide supported Pt particles

Cited by 40 publications

References 39 publications

Promotional effect of metal encapsulation on reactivity of iron oxide supported Pt catalysts

Promotional effect of metal encapsulation on reactivity of iron oxide supported Pt catalysts

Iron oxide surfaces

On the Activity Enhancing Role of Iron Oxide for Noble Metal Oxidation Catalysts: A CVD-Based Study with Differently Structured Combinations of Pt and FeOx Coatings on Al2O3

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