Compatibility of field emitter studies of oscillating surface reactions with single crystal measurements: catalytic CO oxidation on Pt

Suchorski, Yuri; Imbihl, R.; Medvedev, V.K.

doi:10.1016/s0039-6028(98)00043-0

Cited by 55 publications

(34 citation statements)

References 25 publications

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“…To minimize the influence of the dynamical coupling with neighbouring planes in the revealing of the fieldeffects a particular tip geometry was prepared for a [111]-oriented Pt tip in a way that the {100} planes were less well developed (see insert in the Figure 4a) [37]. The reaction zone was restricted therefore to a triangular area formed by {110} planes which contribute mainly to the total field electron emission current and to the intensity of the FEM image.…”

Section: The Role Of the Applied Field And Compatibility Of The Nm-anmentioning

confidence: 99%

Catalytic reactions on platinum nanofacets: bridging the size and complexity gap

Suchorski

Drachsel

2007

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In this short review we present few selected sections of our own work on the catalytic reactions as studied on a nanoscale using the field emission and field ion microscopies (FEM/FIM) and the corresponding probe-hole techniques: magnetic field ion mass separation combined with the field ion appearance energy spectroscopy (FIAES) and an atom probe with a Wien-filter ion mass selection combined with the time of flight (ToF) and coincidence analyses. We focus on the CO respectively hydrogen oxidation on Pt nanofacets present on an apex of a Pt tip that serves as a model of a single catalytic pellet of a supported catalyst. Exhibiting a heterogeneous surface formed by different orientations, like a catalyst pellet, a Pt tip can be prepared and characterized with atomic resolution. Surface reactions in such a well-defined system can be monitored with a resolution of £ 2 nm by FEM or FIM and the reacting species originating from few selected surface sites can be analyzed by FIAES or ToF in a probe-hole experiment. By using the single tip the usual averaging of data over at least few catalytic pellets of the common array-type model catalyst is avoided and thus a ''smoothing out'' of the characteristics of the single particles can be eliminated. As a result, the correlation of processes on individual nanofacets and fluctuation effects can be studied in situ. Until now, the FIM/FEM techniques are known to be quite successful in studying the oscillating surface reactions on Pt and Rh surfaces. In the present review we concentrate, in turn, on the local reaction kinetics in the nanosized reaction systems as mirrored by spectroscopic measurements and on the fluctuation-induced deviations from the behaviour predicted by macroscopic rate laws.

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Section: The Role Of the Applied Field And Compatibility Of The Nm-anmentioning

confidence: 99%

Catalytic reactions on platinum nanofacets: bridging the size and complexity gap

Suchorski

Drachsel

2007

Top Catal

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“…Shortly after, video-field ion microscopy was applied to the same reaction at somewhat different reaction pressures and temperatures. As one of the highlights of these combined FEM/FIM research works, cross-shaped kinetic phase diagrams were published with similarities to measurements on extended single crystal surfaces in the absence of high electric fields [2,3]. Other reactions like the water formation from O 2 +H 2 or the NO reduction with H 2 were subsequently studied using video-FEM/FIM along with atom-probe techniques to elucidate the surface composition and the chemical nature of the reaction intermediates [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Field emission techniques for studying surface reactions: Applying them to NO–H2 interaction with Pd tips

Bocarmé

Kruse

2011

Ultramicroscopy

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a b s t r a c tThe adsorption of NO and its reaction with H 2 over Pd tips were investigated by means of field ion microscopy (FIM) and pulsed field desorption mass spectrometry (PFDMS) in the 10 À 3 Pa pressure range and at sample temperatures between 400 and 600 K. By varying the H 2 partial pressure while keeping the other control parameters constant, the NO +H 2 reaction over Pd crystallites is shown to exhibit a strong hysteresis effect. The hysteresis region narrows with increase in temperature and the H 2 pressures delimiting this hysteresis decrease as well. Abrupt transformations of the micrographs are observed by FIM from bright to dark patterns and vice versa. These transformations define the hysteresis region. The collected data allow establishing a novel kinetic phase diagram of the NO + H 2 /Pd system within the range of temperatures and pressures indicated. The observed features are correlated with a local chemical analysis by means of field pulses. NO + seems to be the dominating imaging species under all conditions. At high relative H 2 pressures (the ''hydrogen-side''), H atoms seem to diffuse subsurface. This process is blocked at lower H 2 pressure (the ''NO-side'') due to NO ad and O ad accumulation on the surface. Probe-hole measurements with field pulses indicate that the Pd surface undergoes oxidation as revealed by the occurrence of PdO 2 + species in the mass spectra.

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“…Field-modified binding energies of adsorbates influence the adsorption kinetics, shifting the adsorption equilibrium of coadsorbed species. In the case of the catalytic reaction this results in a significant field-induced shift of the kinetic phase diagram as was directly demonstrated for the CO oxidation [42] and for the H 2 oxidation [43,44] by in situ FIM of corresponding reactions. Moreover, in the case of positively charged tip, high electric field may even lead to the field-induced grains of the Rh foil and by FEM for the Rh tip apex, with the latter characterized at atomic resolution by FIM.…”

Section: Discussionmentioning

confidence: 71%

“…Therefore, the present FEM studies, for which field values of less than 5 V/nm were used, can be considered as quasi field-free, as proven in our previous study of the CO oxidation on Pt using a pulsed high-voltage supply with varying duty pulses [42]. Thus the present FEM results allow, in contrary to the FIM measurements, a direct comparison with the PEEM data without any field-effect corrections.…”

Section: Peem Studiesmentioning

confidence: 74%

Hydrogen Oxidation on Stepped Rh Surfaces: µm-Scale versus Nanoscale

et al. 2016

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Compatibility of field emitter studies of oscillating surface reactions with single crystal measurements: catalytic CO oxidation on Pt

Cited by 55 publications

References 25 publications

Catalytic reactions on platinum nanofacets: bridging the size and complexity gap

Catalytic reactions on platinum nanofacets: bridging the size and complexity gap

Field emission techniques for studying surface reactions: Applying them to NO–H2 interaction with Pd tips

Hydrogen Oxidation on Stepped Rh Surfaces: µm-Scale versus Nanoscale

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