Infrared Reflection−Absorption Study of Carbon Monoxide Adsorption on Fe/Pt(111) Bimetallic Surfaces

Wadayama, Toshimasa; Osano, H.; Maeyama, T.; Yoshida, H.; Murakami, Koji; Todoroki, Naoto; Oda, Satoshi

doi:10.1021/jp712095w

Cited by 19 publications

(16 citation statements)

References 50 publications

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“…In addition, if formed upon reduction of the FeO film, the Fe overlayer on Pt(111) would manifest itself by the IRAS signal either at ~1950 cm -1 (at 343 K) or at 2060 cm -1 (at 473 K), the latter being due to Fe migration into the sub-surface region as reported in [38]. All scenarios are inconsistent with the spectra shown in Fig.…”

Section: Resultsmentioning

confidence: 80%

Monolayer iron oxide film on platinum promotes low temperature CO oxidation

Sun

Qin

Lewandowski

et al. 2009

Journal of Catalysis

224

236

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Abstract. CO oxidation on a clean Pt(111) single crystal and thin iron oxide films grown on Pt(111) was studied at different CO:O 2 ratios (between 1:5 and 5:1) and partial pressures up to 60 mbar at 400 -450 K. Structural characterization of the model catalysts was performed by scanning tunneling microscopy, low energy electron diffraction, Auger electron spectroscopy and temperature programmed desorption. It is found that monolayer FeO (111) films grown on Pt(111) are much more active than clean Pt(111) and nm-thick Fe 3 O 4 (111) films at all reaction conditions studied. Post-characterization of the catalysts revealed that at CO:O 2 >1 the FeO(111) film dewets the Pt surface with time, ultimately resulting in highly dispersed iron oxide particles on Pt(111). The film dewetting was monitored in situ by polarisation-modulated infrared reflection absorption spectroscopy. The reaction rate at 450 K exhibited first order for O 2 and non-monotonously depended on CO pressure. In O 2 -rich ambient the films were enriched with oxygen while maintaining the long range ordering.Based on the structure-reactivity relationships observed for the FeO/Pt films, we propose that the reaction proceeds through the formation of a well-ordered, oxygen-rich FeO x (1 < x < 2) film that reacts with CO through the redox mechanism. The reaction induced dewetting in fact deactivates the catalyst. The results may aid in our deeper understanding of reactivity of metal particles encapsulated by thin oxide films as a result of strong metal support interaction.

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Section: Resultsmentioning

confidence: 80%

Monolayer iron oxide film on platinum promotes low temperature CO oxidation

Sun

Qin

Lewandowski

et al. 2009

Journal of Catalysis

224

236

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“…For this low Fe coverage one would expect Fe decorating the step edges. However, according to infrared studies [32] and Monte-Carlo simulations [33], the Fe atoms may also migrate into the sub-surface region of Pt at temperatures above ~ 450 K. Nonetheless, Figure 2b shows that the intensity of the high temperature peak (~ 510 K) on the Fe/Pt(111) surface is reduced by a factor of 2, while the CO capacity of the (111) terraces is almost unchanged.…”

Section: Resultsmentioning

confidence: 96%

CO adsorption and dissociation on iron oxide supported Pt particles

et al. 2009

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Abstract. We studied CO adsorption on Pt part icles deposited on well-ordered Fe3O4 (111) thin films grown on Pt(111) by temperature programmed desorption (TPD). A highly stepped Pt(111) surface produced by ion sputter ing and annealing at 600 K was studied for comparison. Structural characterization was performed by scanning tunneling microscopy and Auger electron spectroscopy. The TPD spectra revealed that in addition to the desorption peaks at ~ 400 and ~ 480 K, assigned to CO adsorbed on Pt(111) facets and low -coordination sites respectively, the Pt nanoparticles annealed at 600 K exhibit a desorption state at ~ 270 K.This state is assigned to initial stages of strong metal-support interaction resulting in partial Fe-Pt intermixing. On both Pt/Fe 3 O 4 (111) and stepped Pt(111) surfaces CO is found to dissociate at 500 K. The results suggest that CO dissociation and carbon accumulation occur on the low-coordinated Pt sites.

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“…a 10-min CO exposure at the given CO pressure. The peak observed at 2,095 cm −1 is typical for the stretching vibration of CO adsorbed at the top sites of Pt(111), and the weaker broad peak around 1,850 cm −1 is due to CO adsorbed at the bridge sites of Pt(111) (36,37). As the CO exposure pressure rose from 1 × 10 −9 to 1 × 10 −6 Torr, a new peak centered at 2,081 cm −1 appeared and its intensity was increased substantially with the CO pressure, becoming almost comparable to that of the peak at 2,095 cm −1 after 1 × 10 −6 Torr CO exposure.…”

Section: Significancementioning

confidence: 99%

Graphene cover-promoted metal-catalyzed reactions

Yao

Zhang

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

191

189

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Graphitic overlayers on metals have commonly been considered as inhibitors for surface reactions due to their chemical inertness and physical blockage of surface active sites. In this work, however, we find that surface reactions, for instance, CO adsorption/desorption and CO oxidation, can take place on Pt(111) surface covered by monolayer graphene sheets. Surface science measurements combined with density functional calculations show that the graphene overlayer weakens the strong interaction between CO and Pt and, consequently, facilitates the CO oxidation with lower apparent activation energy. These results suggest that interfaces between graphitic overlayers and metal surfaces act as 2D confined nanoreactors, in which catalytic reactions are promoted. The finding contrasts with the conventional knowledge that graphitic carbon poisons a catalyst surface but opens up an avenue to enhance catalytic performance through coating of metal catalysts with controlled graphitic covers.arbonaceous deposits such as carbidic carbon and graphitic carbon often form on transition metal (TM) surfaces in catalytic processes involving carbon-containing reactants (1). It has been shown that carbidic species can be involved in some hydrogenation reactions, which are attributed to the observed high reaction activity (2-5). In contrast, graphitic carbon deposited on TM is conventionally considered as catalyst poison due to its chemical inertness and physical blockage of surface active sites (6-8). It has been generally assumed that formation of graphitic carbon on metal catalysts should be avoided before and during catalytic reactions (9, 10). Nevertheless, for decades, extensive research efforts have been made to use surface carbon layers formed on TMs and to understand their role in catalytic reactions (11)(12)(13)(14), which, however, have been impeded by complexity of the ill-defined carbon structures. Graphene, as a simple form of graphitic deposit, has been grown on many late TM surfaces via catalytic cracking of carbon-containing gases (15)(16)(17)(18)(19)(20). Surface science studies on the well-defined graphene/metal surfaces have shown that gaseous molecules such as CO, O 2 , and H 2 O can be readily intercalated under the graphene overlayers (21-27). Defects in graphene including island edges (22,23,(28)(29)(30), domain boundaries (26,31,32), and wrinkles (33) provide channels for molecule diffusion into the graphene/metal interfaces. These new results raise the intriguing possibility that the space between graphene overlayers and metal substrates can act as a 2D container for reactions. The distance between the graphene overlayers and the metal surfaces typically falls in the subnanometer range (19,20), and molecules trapped inside interact directly with both the graphene cover and the metal substrate. Catalytic reactions, if occurring, are strongly confined in the 2D space, and extraordinary catalytic performance may be expected due to the confinement effect. In the present work, graphene/Pt(111) [Gr/Pt(111)] was used ...

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Infrared Reflection−Absorption Study of Carbon Monoxide Adsorption on Fe/Pt(111) Bimetallic Surfaces

Cited by 19 publications

References 50 publications

Monolayer iron oxide film on platinum promotes low temperature CO oxidation

Monolayer iron oxide film on platinum promotes low temperature CO oxidation

CO adsorption and dissociation on iron oxide supported Pt particles

Graphene cover-promoted metal-catalyzed reactions

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