Self-Organization of Ultrathin Vanadium Oxide Layers on a Rh(111) Surface during a Catalytic Reaction. Part II: A LEEM and Spectromicroscopy Study

Lovis, Florian; Hesse, Martin; Locatelli, Andrea; Menteş, Tevfik Onur; Niño, M. Á.; Lilienkamp, G.; Borkenhagen, Benjamin; Imbihl, R.

doi:10.1021/jp206600q

Cited by 18 publications

(23 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At equilibrium, VO x species are known to form various types of ordered structures on Rh(111) depending on temperature, oxygen content, etc. − These structures take the form of well-defined VO x islands in which vanadium and oxygen adatoms assume ordered nanostructures. Under nonequilibrium conditions, i.e., if a catalytic reaction takes place on such VO x -covered surfaces, new mesoscopic structures can emerge. − Striped patterns with a characteristic size ranging between 10 and 100 μm were for example observed on Rh(111)/VO x during exposure to H 2 + O 2 gas mixtures. − Micrometric stripes and round islands were also reported during oxidation of methanol, CO, and ammonia in the same system. , The round islands were shown to correspond to dense VO x domains. Remarkably, it was reported that these VO x -rich islands can move and merge exclusively under reactive conditions, a phenomenon that constitutes a new chemistry-based mechanism for island ripening …”

Section: Introductionmentioning

confidence: 93%

Modeling the Formation and Propagation of VO_x Islands on Rh(111) under Reactive Conditions

2019

Self Cite

View full text Add to dashboard Cite

Phase transitions between different states of a system often involve a long-term maturation process known as ripening, whose mechanism can take various forms. Recent experimental investigations on phase transitions involving vanadium oxides on rhodium have shown the existence of a new ripening mechanism, during which micrometric islands of a dense VO x phase move and coalesce exclusively in the presence of a catalytic reaction. It was hypothesized that this new pathway is fueled by an underlying polymerization/depolymerization process. In this work, we develop a generic reaction-diffusion model containing the basic physicochemical ingredients of these systems. This model reproduces qualitatively the observed behaviors and confirms that it can be traced back to an interplay between intermolecular interactions and the nonequilibrium polymerization process.

show abstract

Section: Introductionmentioning

confidence: 93%

Modeling the Formation and Propagation of VO_x Islands on Rh(111) under Reactive Conditions

2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, with PEEM alone, the interpretation of the images is not clear. Subsequent μXPS measurements (below) showed that the dark islands in Figure 2 represent V-oxide covered area, whereas the surrounding area is largely V-oxide free (Lovis et al, 2011 ; Hesse et al, 2015 ).…”

Section: Reaction Dynamics On Vo X /Rh(111)mentioning

confidence: 99%

Dynamics of Ultrathin Vanadium Oxide Layers on Rh(111) and Rh(110) Surfaces During Catalytic Reactions

Boehn

Imbihl

2020

Front. Chem.

Self Cite

View full text Add to dashboard Cite

Over the past 35 years rate oscillations and chemical wave patterns have been extensively studied on metal surfaces, while little is known about the dynamics of catalytic oxide surfaces under reaction conditions. Here we report on the behavior of ultrathin V oxide layers epitaxially grown on Rh(111) and Rh(110) single crystal surfaces during catalytic methanol oxidation. We use photoemission electron microscopy and low-energy electron microscopy to study the surface dynamics in the 10 −6 to 10 −2 mbar range. On VO x /Rh(111) we find a ripening mechanism in which VO x islands of macroscopic size move toward each other and coalesce under reaction conditions. A polymerization/depolymerization mechanism of VO x that is sensitive to gradients in the oxygen coverage explains this behavior. The existence of a substructure in VO x islands gives rise to an instability, in which a VO x island shrinks and expands around a critical radius in an oscillatory manner. At 10 −2 mbar the VO x islands are no longer stable but they disintegrate, leading to turbulent redistribution dynamics of VO x. On the more open and thermodynamically less stable Rh(110) surface the behavior of VO x is much more complex than on Rh(111), as V can also populate subsurface sites. At low V coverage, one finds traveling interface pulses in the bistable range. A state-dependent anisotropy of the surface is presumably responsible for intriguing chemical wave patterns: wave fragments traveling along certain crystallographic directions, and coexisting different front geometries in the range of dynamic bistability. Annealing to 1000 K causes the formation of macroscopic VO x islands. Under more reducing conditions dendritic growth of a VO x overlayer is observed.

show abstract

“…However, it is at this point that the application of model surfaces becomes relevant; so correlations between structure and/or composition with chemical reactivity can be made. Many examples of this kind of characterization can be found in the literature for different types of model systems, ranging from bimetallic surfaces [26][27][28] to hybrid oxide-metallic systems [29][30][31].…”

Section: Application In Catalysismentioning

confidence: 99%

“…Due to its wide applicability, it is important to rationally understand the working principle of the catalyst under different experimental conditions. In this sense, Lovis et al [29,30,46] have used LEEM and PEEM to address the properties of a V x O y /Rh(111) model system, establishing a representative example of what can be done and what kind of information can be extracted from a model system with this approach. For instance, their studies were focused on the dynamic changes that occur on the oxide phase when the model catalyst is exposed to reaction condition, in this case being the hydrogen oxidation reaction.…”

Section: Application In Catalysismentioning

confidence: 99%

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

Prieto

Schmidt

2017

Catal Lett

View full text Add to dashboard Cite

Catalysis is a hot topic in research with the focus on finding catalysts that show better activity or selectivity on processes on technological or industrial interest. The use of model systems of applicable materials has proven to be a successful approach in the last decades to obtain information on the fundamental properties of these materials, leading eventually to a better understanding how real catalysts work. This knowledge is extremely important in the sense that it allows an optimization of the catalyst composition, thus leading to a rational design of new materials. For these fundamental studies, a variety of probing techniques such as X-ray photo-electron spectroscopy, scanning tunnel microscopy, and temperature programmed desorption have been applied. In this article, we discuss how low energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) can contribute to the fundamental understanding of relevant surface processes taking place on model catalysts. Also, the capability of these techniques on addressing open questions in catalysis is discussed

show abstract

Self-Organization of Ultrathin Vanadium Oxide Layers on a Rh(111) Surface during a Catalytic Reaction. Part II: A LEEM and Spectromicroscopy Study

Cited by 18 publications

References 33 publications

Modeling the Formation and Propagation of VO_x Islands on Rh(111) under Reactive Conditions

Modeling the Formation and Propagation of VO_x Islands on Rh(111) under Reactive Conditions

Dynamics of Ultrathin Vanadium Oxide Layers on Rh(111) and Rh(110) Surfaces During Catalytic Reactions

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

Contact Info

Product

Resources

About

Self-Organization of Ultrathin Vanadium Oxide Layers on a Rh(111) Surface during a Catalytic Reaction. Part II: A LEEM and Spectromicroscopy Study

Cited by 18 publications

References 33 publications

Modeling the Formation and Propagation of VOx Islands on Rh(111) under Reactive Conditions

Modeling the Formation and Propagation of VOx Islands on Rh(111) under Reactive Conditions

Dynamics of Ultrathin Vanadium Oxide Layers on Rh(111) and Rh(110) Surfaces During Catalytic Reactions

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

Contact Info

Product

Resources

About

Modeling the Formation and Propagation of VO_x Islands on Rh(111) under Reactive Conditions

Modeling the Formation and Propagation of VO_x Islands on Rh(111) under Reactive Conditions