Profile

The activities of the Steinrück group focus in the area of surface and interface science with main research interests in:

1. Development of new materials with novel electronic, geometric, and chemical properties
2. Investigation of elementary steps of surface reactions
3. Construction of advanced scientific apparatus

These studies aim at a fundamental physical and chemical understanding of the mechanisms and processes involved, at an atomic level. A large variety of state-of-the-art experimental techniques is applied, partly utilizing synchrotron radiation. The methods range from high resolution X-ray photoelectron spectroscopy (XPS), angle-resolved UV- und X-ray photoelectron spectroscopy (ARUPS, ARXPS), Auger electron spectroscopy (AES, XAES), photoelectron diffraction (PED), electron energy loss spectroscopy (EELS), near edge X-ray absorption fine structure measurements (NEXAFS), temperature programmed desorption (TPD), work function measurements, low energy ion scattering (LEIS), and molecular beam methods (Maxwellian beams and supersonic beams) to low energy electron diffraction (LEED, including LEED-IV analysis), scanning tunneling microscopy (STM), scanning electron (SEM), and scanning Auger microscopy (SAM). The measurements at synchrotron radiation facilities are performed since 1986, mainly at BESSY and BESSY II, but also at MAX-lab, ELETTRA, SSRL, ALS and ESRF. In addition, the development of experimental methods is put forward, concerning technical improvements as well as the understanding of the underlying fundamental concepts.

In the following the ongoing projects and their major results are summarized and important past highlights are briefly addressed.

Ionic Liquid Surface Science concerns pioneering work addressing the liquid/vacuum and liquid/solid interface of ionic liquids (ILs). Using an interdisciplinary approach, in cooperation with the synthetically oriented group of Prof. Peter Wasserscheid, the fundamental relations between the chemical structure of known and new ILs and their bulk and surface properties as well as their reactivity are studied. In the focus are non-functionalized and functionalized ILs, mixtures of ILs, transition metal complexes dissolved in ILs, in situ reaction studies and the interaction of gases and organic molecules with ILs. The studies benefit from the extremely low vapor pressure of most ILs, which enables their investigation with surface science methods in ultra-high vacuum, in particular with angle-resolved X-ray photoelectron spectroscopy (ARXPS). The work was funded by an ERC Advanced Grant (2016-2022) and SFB 1452 (2021-2025).

The adsorption and reactivity of redox-active metalloporphyrins were and are studied by the Steinrück group in the collaborative research center SFB 583 “Redox Active Metal Complexes – Controlling Reactivity Through Molecular Architectures” (2004-2012) and the research unit (FOR) 1878 “funCOS – Functional Molecular Structures on Complex Oxide Surfaces“(2014-2022). Specific attention is paid to well-defined porphyrin layers, in particular monolayers, on metal and oxide surfaces. The investigations focus on novel surface reactions, such as the direct in situ metalation of adsorbed free base porphyrins, in order to produce highly reactive metalloporphyrins, and the adsorption and complexation of small molecules (NH₃, NO, CO, O₂) at the coordinated metal centers. The reactivity of these centers (Fe, Co, Ni, Zn, Cu) can be tailored by the electronic interaction with the underlying surface (substrate) by variation of either the substrate or the distance between substrate and metal center by the attachment of appropriate ligands at the periphery of the macrocycle. Additional important aspects are the intramolecular conformation of the porphyrins and other tetrapyrroles and the formation of supramolecular networks. The applied experimental methods are mainly photoelectron spectroscopy and scanning tunneling microscopy.

In situ studies of surface reactions provide detailed insights in the relevant elementary steps during adsorption and reaction of molecules on single crystal surfaces and during their thermal evolution. In 1999, the Steinrück group built up a UHV apparatus, which combines high resolution X-ray photoelectron spectroscopy with a supersonic molecular beam. At a third generation synchrotron facility, such as BESSY II in Berlin, this setup allows to measure highly resolved XP spectra with very short measurement times (down to 1 spectrum/second) as function of pressure, temperature, structure or coverage. Due to the high resolution, different surface species can be identified and quantified. This enables to derive detailed conclusions on reaction mechanisms and kinetics. Fundamental insights have been obtained concerning the adsorption of small molecules (NO, O₂, CO₂, H₂O, SO₂), the oxidation of CO or atomic sulphur, and the adsorption of various saturated and non-saturated hydrocarbons (CH₄, C₂H₂, C₂H₄, C₂H₆, C₆H₆) on flat and stepped metal surfaces and also on oxide surfaces.

A related topic is near ambient pressure XPS in the so-called “pressure gap”. These studies aim at bridging the gap between classical UHV experiments on model systems and the ambient conditions in real catalysis. Using a spectrometer built in 2001/2002 that is equipped with a triply differentially pumped electron analyzer and a differentially pumped Al-K_α source, XPS measurements can be performed up to 1 mbar, i.e. up to pressures close to those relevant in real systems. Major topics in this project were, e.g., methanol steam reforming at PdZn catalysts, the catalytic properties of nanosized Au and Pt, liquid Ga-based catalysts, and CO₂ capture.

The studies were expanded on Liquid Organic Hydrogen Carriers (LOHCs). These molecules are an attractive and promising alternative to the present storage of hydrogen at high pressures or low temperatures. Suitable organic molecule pairs such as Perhydro-N-ethylcarbazole/N-ethylcarbazole (H₁₂-NEC/NEC) and Perhydrodibenzyltoluol/Dibenzyltoluene are considered as promising candidates. The hydrogen-lean compound can be hydrogenated over suitable catalysts to the hydrogen-rich form, that is, hydrogen can be stored. On demand, the hydrogen-rich form can be dehydrogenated to the hydrogen-lean form, again over a suitable catalyst, thereby releasing the hydrogen to be used in mobile or stationary applications. Aim of this work is to test new molecules for hydrogen storage and to develop improved catalysts.

Since 2010 the Steinrück group studies the chemical modification of supported graphene (on metal substrates) by heteroatoms (SFB 953 “Synthetic carbon allotropes” (2012-2023)). Strategies for the modification are the preadsorption or codeposition of N- or B-containing molecules, the dosage of reactive species using a supersonic molecular beam, functionalization with rylenes and porphyrins, hydrogenation to graphane and intercalation of metals. In addition, the in situ synthesis of macromolecular structures is foreseen on metal surfaces. As experimental method, predominantly X-ray photoelectron spectroscopy is applied, using synchrotron radiation at BESSY II.

Electron Beam Induced Deposition (EBID) of nanostructures on different surfaces (metals, semiconductors and oxides) is one further major research activity. The Steinrück group could demonstrate that upon electron beam induced deposition of adsorbed precursor molecules, e.g. Fe(CO)₅, under ultra-high vacuum conditions, a hitherto unreached purity of the metal deposits of >95% can be achieved, with lateral dimensions down to <10 nm. Recently, a new and promising variant of electron beam induced processing of surfaces was developed for the production of clean and laterally well-defined nanostructures. In this novel two step approach first, an oxide surface is locally "activated" by the highly focused electron beam prior to dosing the precursor gas. Secondly, the preactivated structure is "developed" by exposing the surface to the precursor gas, which dissociates only in the preactivated regions. A further important goal is the investigation of fundamental aspects of electron-precursor and electron-substrate interactions.

Other research activities, for which the research team of Prof. Steinrück has received significant attention and recognition in the past, are:

Electronic Structure of ultrathin metal layers and alloys: Preparation, characterization, electronic band structure, and correlations between electronic and chemical properties.

Oxide surfaces and surface oxides: Characterization, growth, deposition of metals, adsorption of small molecules, strong metal support interaction (SMSI).

Electronic properties, structure and orientation of small molecules on metal surfaces: Interplay of adsorbate-adsorbate and adsorbate-substrate interactions, one- and two-dimensional adsorbate band structures, pure and coadsorbed molecular layers, angle-resolved UV photoelectron spectroscopy, symmetry selection rules, near edge X-ray absorption spectroscopy (NEXAFS), LEED-IV analysis.

Molecular beam studies of gas-surface interactions: Microscopic reversibility, detailed balance, energy and angular dependence of sticking coefficients, angular dependence of desorbing molecules, adsorption kinetics and dynamics.

Electronic properties, 3D band structure and valence band offsets of II-VI semiconductors and heteroepitactical layers: Experimental determination of the band structure, UV photoelectron spectroscopy, electron energy loss spectroscopy, ZnSe, BeTe, CdTe.

Photoelectron holography: First experimental demonstration of the applicability of this approach (sulphur on Ni(111)); fundamental experimental studies concerning photoelectron diffraction.

Final state effects in photoelectron spectroscopy: Photon energy dependence of the cross section, shape resonances, dynamical Jahn-Teller effects in UV photoelectron spectroscopy, vibrational excitations in X-ray photoelectron spectroscopy.

Development of new experimental apparatus: Setups for measuring the angular dependence of sticking coefficients and desorption fluxes; simple helium scattering apparatus; UHV chambers for fast XPS (down to 1 spectrum per sec), near ambient pressure XPS (up to 1 mbar) and microcalorimetry.

• M. Moritz, S. Maisel, N. Raman, H. Wittkämper, C. Wichmann, M. Grabau, D. Kahraman, J. Steffen, N. Taccardi, A. Görling, M. Haumann, P. Wasserscheid, H.-P. Steinrück, C. Papp
  Supported Catalytically Active Liquid Metal Solutions: Liquid Metal Catalysis with Ternary Alloys, Enhancing Activity in Propane Dehydrogenation
  ACS Catal. 14 (2024) 6440-6450. / DOI: 10.1021/acscatal.4c01282
• L. Winter, S. Trzeciak, C. C. Fernández, S. Massicot, T. Talwar, F. Maier, D. Zahn, H.-P. Steinrück
  Tailoring the Selectivity of 1,3-Butadiene versus 1-Butene Adsorption on Pt(111) by Ultrathin Ionic Liquid Films
  ACS Catal. 13 (2023) 10866-10877. / DOI: 10.1021/acscatal.3c02126
• D. Hemmeter, D. Kremitzl, P. Schulz, P. Wasserscheid, F.Maier, H.-P. Steinrück
  The Buoy Effect: Surface Enrichment of a Pt Complex in IL Solution by Ligand Design
  Chem. Eur. J. 29 (2023) e202203325 1-7. / DOI: 10.1002/chem.202203325
• E. M. Freiberger, F. Späth, U. Bauer, F. Düll, P. Bachmann, J. Steinhauer, F. Hemauer, N. J. Waleska, V. Schwaab, H.-P. Steinrück, C. Papp
  Selective Oxygen and Hydrogen Functionalization of the h-BN/Rh(111) Nanomesh
  Chem. Eur. J. 27 (2021) 13172-13180. / DOI: 10.1002/chem.202101946
• M. Meusel, M. Lexow, A. Gezmis, S. Schötz, M. Wagner, A. Bayer, F. Maier, H.-P. Steinrück
  Atomic Force and Scanning Tunneling Microscopy of Ordered Ionic Liquid Wetting Layers from 110 K up to Room Temperature
  ACS Nano 14 (2020) 9000-9010. / DOI: 10.1021/acsnano.0c03841
• R. Bhuin, L. Winter, M. Lexow, F. Maier, H.-P. Steinrück
  Die dynamische Wechselwirkung von n-Butan mit Imidazolium-basierten ionischen Flüssigkeiten
  Angew. Chem. Int. Ed. 59 (2020) 14429-14433. / DOI: 10.1002/anie.202005991
• N. Raman, S. Maisel, M. Grabau, N. Taccardi, J. Debuschewitz, M. Wolf, H. Wittkämper, T. Bauer, M. Wu, M. Haumann, C. Papp, A. Görling, E. Spiecker, J. Libuda, H.-P. Steinrück, P. Wasserscheid
  Highly Effective Propane Dehydrogenation Using Ga-Rh Supported Catalytically Active Liquid Metal Solutions
  ACS Catalysis 9 (2019) 9499-9507. / DOI: 10.1021/acscatal.9b02459
• V. Lloret, M. Á. Rivero-Crespo, J. A. Vidal-Moya, S. Wild, A. Doménech-Carbó, B. S. J. Heller, S. Shin, H.-P. Steinrück, F. Maier, F. Hauke, M. Varela, A. Hirsch, A. Leyva-Pérez, G. Abellán
  Few layer 2D pnictogens catalyze the alkylation of soft nucleophiles with esters
  Nat. Commun. 10 (2019) 509 1-11. / DOI: 10.1038/s41467-018-08063-3
• M. Lepper, J. Köbl, L. Zhang, M. Meusel, H. Hölzel, D. Lungerich, N. Jux, A. de Siervo, B. Meyer, H.-P. Steinrück, H. Marbach
  Controlling the Self-Metalation Rate of Tetraphenylporphyrins on Cu(111) via Cyano Functionalization
  Angew. Chem. Int. Ed. 57 (2018) 10074-10079. / DOI: 10.1002/anie.201803601
• N. Taccardi, M. Grabau, J. Debuschewitz, M. Distaso, M. Brandl, R. Hock, F. Maier, C. Papp, J. Erhard, C. Neiss, W. Peukert, A. Görling, H.-P. Steinrück, P. Wasserscheid
  Gallium-rich Pd–Ga phases as supported liquid metal catalysts
  Nat. Chem. 9 (2017) 862-867. / DOI: 10.1038/nchem.2822
• D. Fantauzzi, S. Krick Calderón, J. E. Mueller, M. Grabau, C. Papp, H.-P. Steinrück, T. P. Senftle, A. C. T. van Duin, T. Jacob
  Growth of Stable Surface Oxides on Pt(111) at Near-Ambient Pressures
  Angew. Chem. Int. Ed. 56 (2017) 2594-2598. / DOI: 10.1002/anie.201609317
• F. Rietzler, B. May, H.-P. Steinrück, F. Maier
  Switching adsorption and growth behavior of ultrathin [C₂C₁Im][OTf] films on Au(111) by Pd deposition
  Phys. Chem. Chem. Phys. 18 (2016) 25143-25150. / DOI: 10.1039/c6cp04938a
• M. Franke, F. Marchini, N. Jux, H.-P. Steinrück, O. Lytken, F. J. Williams
  Zinc Porphyrin Metal-Center Exchange at the Solid-Liquid Interface
  Chem. Eur. J. 22 (2016) 8520-8524. / DOI: 10.1002/chem.201600634
• K. Gotterbarm, F. Späth, U. Bauer, C. Bronnbauer, H.-P. Steinrück, C. Papp
  Reactivity of Graphene-Supported Pt Nanocluster Arrays
  ACS Catal. 5 (2015) 2397-2403. / DOI: 10.1021/acscatal.5b00245
• S. Ditze, M. Stark, F. Buchner, A. Aichert, N. Jux, N. Luckas, A. Görling, W. Hieringer, J. Hornegger, H.-P. Steinrück, H. Marbach
  On the Energetics of Conformational Switching of Molecules at and Close to Room Temperature
  J. Am. Chem. Soc. 136 (2014) 1609-1616. / DOI: 10.1021/ja411884p
• I. Niedermaier, M. Bahlmann, C. Papp, C. Kolbeck, W. Wei, S. Krick Calderón, M. Grabau, P. S. Schulz, P. Wasserscheid, H.-P. Steinrück, F. Maier
  Carbon Dioxide Capture by an Amine Functionalized Ionic Liquid: Fundamental Differences of Surface and Bulk Behavior
  J. Am. Chem. Soc. 136 (2014) 436-441. / DOI: 10.1021/ja410745a
• I. Niedermaier, N. Taccardi, P. Wasserscheid, F. Maier, H.-P. Steinrück
  Probing a Gas/Liquid Acid-Base Reaction by X-ray Photoelectron Spectroscopy
  Angew. Chem. Int. Ed. 52 (2013) 8904-8907. / DOI: 10.1002/anie.201304115
• C. Gleichweit, M. Amende, S. Schernich, W. Zhao, M. P. A. Lorenz, O. Höfert, N. Brückner, P. Wasserscheid, J. Libuda, H.-P. Steinrück, C. Papp
  Dehydrogenation of Dodecahydro-N-ethylcarbazole on Pt(111)
  ChemSusChem 6 (2013) 974-977. / DOI: 10.1002/cssc.201300263
• S. Ditze, M. Stark, M. Drost, F. Buchner, H.-P. Steinrück, H. Marbach
  Activation Energy for the Self-Metalation Reaction of 2H-tetraphenylporphyrin on Cu(111)
  Angew. Chem. Int. Ed. 51 (2012) 10898-10901. / DOI: 10.1002/anie.201205464
• C. Kolbeck, I. Niedermaier, N. Taccardi, P. S. Schulz, F. Maier, P. Wasserscheid, H.-P. Steinrück
  Monitoring of Liquid-Phase Organic Reactions by Photoelectron Spectroscopy
  Angew. Chem. Int. Ed. 51 (2012) 2610-2613 (VIP article – Inside Back Cover). / DOI: 10.1002/anie.201107402
• J. M. Englert, C. Dotzer, G. Yang, M. Schmid, C. Papp, J. M. Gottfried, H.-P. Steinrück, E. Spiecker, F. Hauke, A. Hirsch
  Covalent Bulk Functionalization of Graphene
  Nature Chem. 3 (2011) 279-286 – Cover. / DOI: 10.1038/nchem.1010
• H.-P. Steinrück, J. Libuda, P. Wasserscheid, T. Cremer, C. Kolbeck, M. Laurin, F. Maier, M. Sobota, P. S. Schulz, M. Stark
  Surface Science and Model Catalysis with Ionic Liquid-Modified Materials
  Adv. Mater. 23 (2011) 2571-2587. / DOI: 10.1002/adma.201100211
• M.-M. Walz, M. Schirmer, F. Vollnhals, T. Lukasczyk, H.-P. Steinrück, H. Marbach
  Electrons as “Invisible Ink”: Fabrication of Nanostructures by Local Electron Beam Induced Activation of SiO_x
  Angew. Chem. Int. Ed. 49 (2010) 4669-4673 (VIP article – COVER). / DOI: 10.1002/anie.201001308
• R. Streber, C. Papp, M. P. A. Lorenz, A. Bayer, R. Denecke, H.-P. Steinrück
  Sulfur Oxidation on Pt(355): It is the Steps!
  Angew. Chem. Int. Ed. 48 (2009) 9743-9746. / DOI: 10.1002/anie.200904488
• K. Flechtner, A. Kretschmann, H.-P. Steinrück, J. M. Gottfried
  NO-induced reversible switching of the electronic interaction between a porphyrin-coordinated cobalt ion and a silver surface
  J. Am. Chem. Soc. 129 (2007) 12110-12111. / DOI: 10.1021/ja0756725
• J. M. Gottfried, K. Flechtner, A. Kretschmann, T. Lukasczyk, H.-P. Steinrück
  Direct synthesis of a metalloporphyrin complex on a surface
  J. Am. Chem. Soc. 128 (2006) 5644-5645. / DOI: 10.1021/ja0610333
• F. Maier, J. M. Gottfried, J. Rossa, D. Gerhard, P. S. Schulz, W. Schwieger, P. Wasserscheid, H.-P. Steinrück
  Surface enrichment and depletion effects of ions dissolved in an ionic liquid: An X-ray photoelectron spectroscopy study
  Angew. Chem. Int. Ed. 45 (2006) 7778-7780. / DOI: 10.1002/anie.200602756

• D. Hemmeter, M. Haumann, F. J. Williams, T. M. Koller, P. Wasserscheid, K. Meyer, F. Maier, H.-P. Steinrück
  Towards Surface-Enhanced Homogeneous Catalysis: Tailoring the Enrichment of Metal Complexes at Ionic Liquid Surfaces
  Angew. Chem. Int. Ed. 64 (2025) e202422693 1-26. / DOI: 10.1002/anie.202422693
• M. Lexow, F. Maier, H.-P. Steinrück
  Ultrathin ionic liquid films on metal surfaces: adsorption, growth, stability and exchange phenomena
  Adv. Phys.: X 5 (2020) 1761266 1-47. / DOI: 10.1080/23746149.2020.1761266
• F. Maier, I. Niedermaier, H.-P. Steinrück
  Perspective: Chemical reactions in ionic liquids monitored through the gas (vacuum)/liquid interface
  J. Chem. Phys. 146 (2017) 170901 1-15. / DOI: 10.1063/1.4982355
  Invited Perspective Article – COVER
• H.-P. Steinrück and P. Wasserscheid
  Ionic Liquids in Catalysis
  Catal. Lett. 145 (2015) 380-397. / DOI: 10.1007/s10562-014-1435-x
  Invited Review
• C. Papp, P. Wasserscheid, J. Libuda, H.-P. Steinrück
  Liquid Organic Hydrogen Carriers: Surface Science Studies of Carbazole Derivatives
  Chem. Rec. 14 (2014) 879-896. / DOI: 10.1002/tcr.201402014
  Invited Contribution
• H. Marbach and H.-P. Steinrück
  Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature
  Chem. Commun. 50 (2014) 9034-9048. / DOI: 10.1039/C4CC01744G
  Feature Article on Invitation
• C. Papp and H.-P. Steinrück
  In situ high-resolution X-ray photoelectron spectroscopy – Fundamental insights in surface reactions
  Surf. Sci. Rep. 68 (2013) 446-487. / DOI: 10.1016/j.surfrep.2013.10.003
• H.-P. Steinrück
  Recent developments in the study of ionic liquid interfaces using X-ray photoelectron spectroscopy and potential future directions
  Phys. Chem. Chem. Phys. 14 (2012) 5010-5029. / DOI: 10.1039/C2CP24087D
  Invited Perspective Article – COVER
• K. R. J. Lovelock, I. J. Villar-Garcia, F. Maier, H.-P. Steinrück, P. Licence
  Photoelectron Spectroscopy of Ionic Liquid Based Interfaces
  Chem. Rev. 110 (2010) 5158-5190. / DOI: 10.1021/cr100114t
• H.-P. Steinrück
  Surface Science goes liquid !
  Surf. Sci. 604 (2010) 481-484. / DOI: 10.1016/j.susc.2009.12.033
  Invited Prospective Article
• G. Held and H.-P. Steinrück
  Cyclic hydrocarbons
  Landolt-Börnstein “Physics of Covered Solid Surfaces – Adsorbed Layers on Surfaces”
  Editor: H. P. Bonzel, Vol. III/42, Subvolume A4, Chapter 3.8.7. (2005) pp. 300-369.
  ISBN: 978-3-540-20281-3 / DOI: 10.1007/b12050
  INVITED Contribution
• M. Zharnikov and H.-P. Steinrück
  Holography with photoelectrons: a direct approach
  J. Phys. Condens. Matter 13 (2001) 10533-10560 (Invited Article). / DOI: 10.1088/0953-8984/13/47/302
• H.-P. Steinrück
  Angle-resolved photoemission studies of adsorbed hydrocarbons
  J. Phys. Condens. Matter 8 (1996) 6465-6509. / DOI: 10.1088/0953-8984/8/36/003
  INVITED Topical Review article
• H.-P. Steinrück
  Angle-resolved UV-photoelectron spectroscopy
  Vacuum 45 (1994) 715-731. / DOI: 10.1016/0042-207X(94)90111-2
  INVITED contribution to Special Edition on “Modern Methods of Surface Science and Analysis”