Imbihl group

The Imbihl group investigates the dynamics of surface reactions and develops of catalytic model systems.

RESEARCH EXPERTISE: HETEROGENEOUS CATALYSIS

The Imbihl group focuses on the investigation of the dynamics of surface reactions and the development of catalytic model systems. As a result of self-organization processes, the formation of chemical wave patterns, reaction-induced restructuring of the catalyst and rate oscillations are observed in certain surface reactions. In addition to these phenomena, which can be assigned to the so-called nonlinear dynamics, the working group is working on questions concerning the pressure and material gaps in heterogeneous catalysis, the electrochemical promotion of heterogeneous catalysed reactions and the nano and micro structuring of catalysts.

RESEARCH TOPICS

Heterogeneous catalysis is one of the key technologies of the future in terms of its ability to produce chemicals with low energy and high selectivity, to remove harmful substances from the environment and to convert and store energy.

We deal with model systems of heterogeneous catalysis. This means that the material and structural complexity of the catalysts used in so-called "real catalysis" is reduced to such an extent that, on the one hand, the materials become accessible to surface analytical techniques and, on the other hand, certain aspects that need to be investigated are retained. In the simplest case, model catalysts are single crystals. With a vapor-deposited second metal or oxide, they become models for bimetallic catalysts or for supported oxide catalysts. Under reaction conditions, the structure and composition of catalytic surfaces is determined by dynamic effects: chemical and structural transformations up to morphological changes of the catalyst take place. Under these conditions, however, one is also far away from thermodynamic equilibrium and spatiotemporal self-organization occurs: kinetic oscillations and the formation of chemical wave patterns are well-known examples of such self-organization, but also structural formations such as reaction-induced restructuring are among them. All these processes are also part of the so-called "pressure and material gaps" in heterogeneous catalysis, which is the discrepancy between UHV investigations on single crystals on the one hand and the conditions of "real catalysis" on the other.

The experimental work focuses on spatial resolution methods such as photoemission electron microscopy (PEEM) and ellipsometry. In recent years, so-called "spectromicroscopic" methods using synchrotron radiation and combining the advantages of high-resolution microscopy (~10 nm) with a local (~1 µm) structural and chemical characterization of the imaged phases have become increasingly important for the elucidation of complex spatiotemporal structure formation.

Initially, simple reactions of automotive exhaust catalysis such as CO oxidation and NO reduction on Pt, Rh and Pd surfaces were investigated, but in recent years more complex systems such as bimetallic surfaces and supported V-oxide catalysts have been added. Solid state electrochemistry has also established itself as a further field of work.


THESIS OPPORTUNITIES

Master thesis "Restructuring of supported vanadium oxide catalysts on Pd(111) and Pt(111) surfaces".

In the master thesis the restructuring dynamics of vanadium oxide catalysts on precious metal surfaces during methanol oxidation shall be investigated. All experiments will be performed in an ultra-high vacuum system. A photoemission electron microscope (PEEM) will be used as a spatial resolving method. The structure and thickness of ultrathin vanadium oxide catalysts is characterized by electron diffraction and Auger electron spectroscopy. The catalytic activity is evaluated by mass spectrometry. At the beginning of the work ultrathin vanadium oxide catalysts on the substrates Pt(111) and Pd(111) are synthesized and characterized. Subsequently, the catalysts are examined by photoemission electron microscopy during the catalytic reaction to redistribution and restructuring processes. This is the main part of the master thesis. Finally, the catalytic activity is characterized by mass spectrometry. If you are interested, please contact Prof. Dr. Ronald Imbihl.


COOPERATIONS

Experiment

  • Nanospectrsocopy Beamline
    Research group of Dr. Andrea Locatelli at the Synchrotron Elettra
  • ESCA Microscopy Beamline
    Research group of Dr. Luca Gregoratti at the Synchrotron Elettra
  • CIRCE Beamline
    Research group of Dr. Lucia Aballe at the synchrotron ALBA
  • Falta Group
    Research group of Prof. Dr. Jens Falta at the University of Bremen
  • SMART Projekt
    Research group of Dr. Thomas Schmidt at the Helmholtz Zentrum Berlin
  • Dr. Cédric Barroo
    Dr. Cédric Barroo of the Université libre de Bruxelles
  • Flege Group
    Research group of Prof. Flege at Brandenburgischen Technischen Universität

Theory

Industry

COOPERATIONS INDUSTRY
  • Elmitec
    Elmitec Elektronenmikroskopie GmbH

CONTACT PERSON

Prof. Dr. rer. nat. Ronald Imbihl
Address
Callinstraße 3a
30167 Hannover
Building
Room
215
Address
Callinstraße 3a
30167 Hannover
Building
Room
215