Institute of Materials Chemistry
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Head of researchgroup

Univ.Ass. Mag.rer.nat. Dr.rer.nat. Christoph Rameshan

Address:
Getreidemarkt 9/165
1060 Wien
Austria

Tel.: +43/1/58801-165115
Fax: +43/1/58801-165980

e-mail: christoph.rameshan@tuwien.ac.at

Publications

curriculum vitae

Research Interests

The main objective of our group is a molecular level understanding of catalytic processes on heterogeneous catalyst surfaces. For that purpose we are utilizing well-defined model systems based on metal single crystals, oxide thin films, and supported metal nanoparticles to study the elemental steps of catalytic reactions. Especially we are interested in the catalytic properties of bimetallic surfaces and nanoparticles. It is well known that e.g. alloys can have very different properties from the constituting metals. For example, PdZn alloys are very good catalysts for methanol steam reforming whereas Pd alone predominantly catalysis methanol decomposition and Zn is not an active catalyst for this reaction.


We are characterizing our model systems in terms of surface structure by Scanning Tunneling Microscopy (STM), Low Energy Ion Scattering (LEIS), and Low Energy Electron Diffraction (LEED). Their chemical composition and electronic properties are obtained by photoelectron spectroscopy (XPS, AES). Available adsorption sites, adsorption/desorption energies, reaction intermediates and possible mechanisms are tested by the adsorption of reactants or probe molecules followed by Infrared - and Temperature Programmed Desorption Spectroscopy (TDS).


To overcome the problems that may arise upon transferring conclusions gained under UHV to a technical catalytic process we are testing the catalytic properties (activity, selectivity) by a combination of reaction analysis (by MS or micro GC) and in-situ Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRAS) and Sum Frequency Generation (SFG) operating from UHV to atmospheric (∼reaction) conditions. Additionally, we have access to in-situ NAP-XPS and EXAFS at synchrotron facilities.


Only the combination of all methods enables us to draw an almost complete picture of what is going on at the surface during the catalytic process and which parameters are influencing the properties of the catalyst.
The combination of surface science techniques with advanced in-situ spectroscopic methods helps us to compare the results obtained from the simplified model systems with industrial grade high surface area powder catalysts.

 
Our current research projects:

  • Methanol Synthesis on Cu based model catalysts (Cu/ZnO, Cu/CeO2) studied by in-situ spectroscopy.
  • Dry Reforming - from understanding the elementary steps to better catalysts
  • Cobalt Oxide Model Catalysis Across the Materials and Pressure Gap
  • SFB-FOXSI Functional Oxide Surfaces and Interfaces; in-situ spectroscopy of chemical reactions on pure and doped ZrO2 thin films and zirconia-based metal-oxide systems
  • Supported Pt nanoparticles as model catalysts
  • Nanoparticle Exsolution: Tailoring the Catalytic Reactivity of Perovskite Type Catalyst Materials in Real Time by Polarization (i.e. applied voltage)

 

Catalytic Reactions

For the studied catalytic reactions, we have a strong focus on environmental protection and sustainable energy production (chemical energy conversion). For example, automotive exhaust gas cleaning, or the utilization and activation of CO2 (Power 2 Gas or Power 2 Fuel). Due to the equilibrium nature of catalytic reactions (and as specific catalyst materials are used for both, synthesis and reforming) we try to study both reaction directions on our model catalysts.

Water Splitting                           2 H2O    ⇌   2 H2 + O2
Water Gas Shift      CO + H2O   ⇌   CO2 + H2reverse WGS
Methanol Reforming        CH3OH + H2O   ⇌   3 H2 + CO2    Methanol Synthesis  
CO2 Electrolysis                        2 CO2   ⇌   2 CO + O2CO Oxidation
Methane dry reforming       CH4 + CO2 → 2 CO + 2 H2

 

 

Instrumentation

Selected Publications

1. Subsurface-controlled CO2-selectivity of PdZn near surface alloys in H2 generation by methanol steam reforming
C. Rameshan, W. Stadlmayr, C. Weilach, S. Penner, H. Lorenz, M. Hävecker, R. Blume, T. Rocha, D. Teschner, A. Knop-Gericke, R. Schlögl, N. Memmel, D. Zemlyanow, G. Rupprechter, B. Klötzer
Angewandte Chemie International Edition 94 (2010), 3224
DOI: 10.1002/anie.200905815

 

 

 

2. Hydrogen Production by Methanol Steam Reforming on Copper Boosted by Zinc-Assisted Water Activation
C. Rameshan, W. Stadlmayr, S. Penner, H. Lorenz, N. Memmel, M. Hävecker, R. Blume, D. Teschner, T. Rocha, D. Zemlyanov, A. Knop-Gericke, R. Schlögl, B. Klötzer
Angewandte Chemie International Edition 41 (2012), 3002
DOI: 10.1002/anie.201106591

3. The growth of an ultrathin zirconia film on Pt3Zr examined by-HR-XPS, TPD, STM and DFT
H. Li, J. Choi, W. Mayr-Schmölzer, C Weilach, C. Rameshan, F. Mittendorfer, J. Redinger, M. Schmid, G. Rupprechter:
Journal of Physical Chemistry C, 119 (2015), 2462
DOI: 10.1021/jp5100846

4. Enhancing Electrochemical Water-Splitting Kinetics by Polarization-Driven Formation of Near-Surface Iron(0): An In Situ XPS Study on Perovskite-Type Electrodes
A.K. Opitz, A. Nenning, Ch. Rameshan, R. Rameshan, R. Blume, M. Hävecker, A. Knop-Gericke, G. Rupprechter, J. Fleig, B. Klötzer
Angewandte Chemie - International Edition, 54 (2015), 2628
DOI: 10.1002/anie.201409527

5.) CO Adsorption on Reconstructed Ir(100) Surfaces from UHV to mbar Pressure: A LEED, TPD, and PM-IRAS Study
K. Anic, A. V. Bukhtiyarov, H. Li, C. Rameshan, G. Rupprechter
J. Phys. Chem. C, 2016, 120 (20), 10838
DOI: 10.1021/acs.jpcc.5b12494

Group Members

Aktuell:

Johannes RaschhoferIntern
Joel HuberBachelor
Elischa Ellersdorfer Bachelor
Lorenz Lindenthal BScMaster Student
Janko Popovic BScMaster Student
Thomas Haunold BScPh.D. Student
Harald Summerer BScPh.D. Student
Raffael Rameshan MScScientist
Thomas Ruh MScScientist
Xia Li, Ph.D.Postdoc
Verena Pramhaas Ph.D.      Postdoc

 

 

Former Group Members

  • PostDoc

    • Dr. Abhijit Bera
    • Dr. Andrey V. Bukhtiyarov
    • Motin Md. Abdul Ph.D

  • PhD Students

    • Dr. Harald Helmuth Holzapfel
    • Dr. Hao Li
    • Dr. Kresimir Anic
    • Dr. Matteo Roiaz

Cooperation Partners

Prof. Günther Rupprechter, Institute of Materials Chemistry, TU Wien

Prof. Konstantin Neyman, Departament de Química Física & Institut de Química Teòrica i Computacional (IQTC-UB), Universitat de Barcelona, Spain

Prof. Andreas Stierle, DESY Nanolab and University of Hamburg, Germany

Assoz. Prof. Bernhard Klötzer, Institut für Physikalische Chemie, Universität Innsbruck, Austria

Dr. Erik Vesselli, Dipartimento di Fisica, Università degli Studi di Trieste / IOM-CNR Laboratorio TASC  

Dr. Hendrik Bluhm, Advanced Light Source, Lawrence BerkeleyNational Laboratory, Berkeley, USA

Prof. Ulrike Diebold, Dr. Gareth Parkinson, Institut für Angewandte Physik, TU Wien

Prof. Jörg Libuda, Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany

Jürgen Fleig / Alex Opitz, Institute of Chemical Technologies and Analytics, Electrochemistry Devision, Technische Universität Wien, Austria

Andrey V. Bukhtiyarov, Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia

SFB "Functional Oxide Surfaces and Interfaces (FOXSI)"