Isothermal oscillations of the hydrogen-oxidation reaction on platinum: investigations in the field electron and field ion microscope

Городецкий, В. В.; Block, J.H.; Drachsel, W.

doi:10.1016/0169-4332(94)90333-6

Cited by 40 publications

(53 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is tempting to study this reaction by field ion microscopy especially as the product molecular water is directly acting as imaging gas [52], thus providing direct access to the reaction sites.…”

Section: Hydrogen Oxidation On Pt Field Emittermentioning

confidence: 99%

“…On Pt, the reaction has been studied in the limit of low coverages [56] as well in the limit of high coverages [57], where the interaction of adjacent adspecies shifts the activation energy to lower values. The hydrogen oxidation on Pt was visualised by FIM and FEM for first time in the former group of Block in Berlin [22,52,58,59] later the FIAES was also applied [60,61]. The imaging process in FIM is governed mainly by the ionisation potential I of the impinging molecule (field ionisation) or by the appearance energy A if the molecule is adsorbed (field desorption), the lower these values the higher (exponentially) the field ion rate is [62].…”

Section: Reaction Kineticsmentioning

confidence: 99%

“…The diversity of the desorbed ''water'' species in Figure 7 gets clearer, if the field induced reaction routes for the H 2 -oxidation according to [52,65] are considered: …”

Section: Reaction Kineticsmentioning

confidence: 99%

See 2 more Smart Citations

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

Suchorski

Drachsel

2007

Top Catal

View full text Add to dashboard Cite

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.

show abstract

Section: Hydrogen Oxidation On Pt Field Emittermentioning

confidence: 99%

Section: Reaction Kineticsmentioning

confidence: 99%

See 1 more Smart Citation

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

Suchorski

Drachsel

2007

Top Catal

View full text Add to dashboard Cite

show abstract

“…For most conditions the NO + intensities are high and therefore contribute strongly, if not exclusively, to the image formation. In contrast to the H 2 -O 2 /Rh and Pt systems, where the produced water acts as the imaging species [28,29], only low amounts of water are detected under the experimental conditions corresponding to the H 2 -and NO-sides of the system (Fig. 4).…”

Section: Pulsed Field Desorption Mass Spectrometrymentioning

confidence: 99%

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

Bocarmé

Kruse

2011

Ultramicroscopy

View full text Add to dashboard Cite

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.

show abstract

“…During the experiments, all the control parameters (temperature, electric field and pressure of both gases) are kept constant: The observed behavior can be said to be self-sustained. The peaks first consist in a sharp increase of the brightness that has been assigned to the formation of water, which is known to decrease the work function [22]. The level of brightness then decreases with a slower pace, down to its initial value.…”

Section: Oscillations During the No 2 + H 2 Reaction On Platinummentioning

confidence: 99%

Nonlinear Dynamics of Reactive Nanosystems: Theory and Experiments

Decker

Bullara

Barroo

et al. 2015

Bottom-Up Self-Organization in Supramolecular Soft Matter

View full text Add to dashboard Cite

Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maintained far enough from their equilibrium state. There are literally hundreds of experimental evidences showing the emergence of such self-organized behaviors at the macroscopic scale. Examples include the appearance of regular oscillations of concentration in both space and time, the formation of stationary spatial organization of reactants and products, and the emergence of spatiotemporal chaos, to cite but a few examples.The theoretical understanding of these phenomena can be considered as being well established. Chemical reactions play a central role in the appearance of complex behaviors because they are nonlinear processes. Indeed, the rates of reactions are typically polynomials of the concentrations and moreover include constants that depend exponentially on the temperature. Because of this, the equations ruling the spatiotemporal development of chemical reactions, which often take the form of reaction-diffusion equations, admit complicated (and even sometimes multiple) solutions. The number and the type of solutions change abruptly for some precise combinations of the parameters of the system, which are known as bifurcation points. This feature explains why new dynamical behaviors are observed only whenever a

show abstract

Isothermal oscillations of the hydrogen-oxidation reaction on platinum: investigations in the field electron and field ion microscope

Cited by 40 publications

References 15 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

Nonlinear Dynamics of Reactive Nanosystems: Theory and Experiments

Contact Info

Product

Resources

About