R. Schlögl's research while affiliated with Fritz Haber Institute of the Max Planck Society and other places

Publications (404)

Article
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Multimodal Operando Electron Microscopy Approach to Study Pt Catalyst During CO Oxidation Reaction - Volume 25 Supplement - M. Plodinec, E. Stotz, L. Sandoval-Diaz, R. Schlögl, T. Lunkenbein
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The original version of this article unfortunately contained an error. The authors would like to correct the error with this erratum. In Fig. 5 the process C and B were incorrectly labelled. The corrected Fig. 5 with the right labelling is included in this erratum. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
Article
An electrode for the oxygen evolution reaction based on a conductive bi-layered free standing graphene support functionalized with iridium nanoparticles was fabricated and characterized by means of potentiometric and advanced X-ray spectroscopic techniques. It was found that the electrocatalytic activity of iridium nanoparticles is associated to th...
Article
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The selective hydrogenation of propyne over a Pd-black model catalyst was investigated under operando conditions at 1 bar making use of advanced X-ray diffraction (bulk sensitive) and photo-electron spectroscopy (surface sensitive) techniques. It was found that the population of subsurface species controls the selective catalytic semi-hydrogenation...
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Alloying provides a means by which to tune a metal catalyst's electronic structure and thus tailor its performance; however, mean-field behaviour in metals imposes limits. To access unprecedented catalytic behaviour, materials must exhibit emergent properties that are not simply interpolations of the constituent components' properties. Here we show...
Article
A novel type of temporal and spatial self-organization in a heterogeneous catalytic reaction is described for the first time. Using in situ x-ray photoelectron spectroscopy, gas chromatography, and mass spectrometry, we show that, under certain conditions, self-sustained reaction-rate oscillations arise in the oxidation of propane over Ni foil beca...
Article
In this account the application of synchrotron radiation based X-ray photoelectron spectroscopy (XPS) for the investigation of electrochemically active gas-solid and liquid-solid interfaces will be discussed. The potential of Near Ambient Pressure XPS (NAP-XPS) for the estimation of the electronic surface structure of electrochemically active inter...
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We activated gold electrodes for their use as electrocatalyst for water splitting by electrodepositing Cu, Ni and Co. A combination of operando x-ray absorption spectroscopy and potentiometric control under aqueous conditions revealed the trends in reactivity yielded by these electrodes, which are directly associated with the cross-and overpotentia...
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In the transition from graphene to graphite, the addition of each individual graphene layer modifies the electronic structure and produces a different material with unique properties. Controlled growth of few-layer graphene is therefore of fundamental interest and will provide access to materials with engineered electronic structure. Here we combin...
Data
In situ SEM movie showing the shrinking behavior of IWC stacking FLG during etching in 25 Pa H2 at 800-900 °C. Images were recorded at a scan rate of one frame per 90 s.
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In situ SEM movies showing the shrinking behavior of a SLG and of a WC stacked FLG during etching in 25 Pa H2 at 900 °C. Etching rates abstracted from this video are discussed in detail in the main manuscript. Images were recorded at a scan rate of one frame per 90 s.
Data
In situ SEM movie showing the growth of multi-layer graphene on Pt in a flow of 10 sccm H2 and 0.1 sccm of C2H4 at 25 Pa and a substrate temperature of 900 °C. Images for this movie were recorded at a scan rate of one frame per 10 s.
Data
In situ SEM movie showing the evolution of a vacancy island on a faceted substrate grain during graphene etching at 25 Pa H2 900 °C. Due to the large number of steps, the etching shows a pronounced anisotropy. Images were recorded at a scan rate of one frame per 90 s.
Data
In situ SEM movies showing the shrinking behavior of a larger number of WC stacked FLG domains during etching in 25 Pa H2 at 900 °C. Etching rates abstracted from this video demonstrate that second layers consistently etch faster than third layers. Images were recorded at a scan rate of one frame per 90 s.
Data
Supplementary Figures 1-5, Supplementary Notes 1-4 and Supplementary References
Data
In situ SEM movie showing the evolution of a vacancy island during graphene etching on a smooth substrate grain at 25 Pa H2 900 °C. In this case, etching gives rise to more regularly shaped holes. Images were recorded at a scan rate of one frame per 90 s.
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The dynamics of graphene growth on polycrystalline Pt foils during chemical vapor deposition (CVD) are investigated using in situ scanning electron microscopy and complementary structural characterization of the catalyst with electron backscatter diffraction. A general growth model is outlined that considers precursor dissociation, mass transport,...
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One of the main goals in catalysis is the characterization of solid/gas interfaces in a reaction environment. The electronic structure and chemical composition of surfaces become heavily influenced by the surrounding environment. However, the lack of surface sensitive techniques that are able to monitor these modifications under high pressure condi...
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Special Issue: Energy Conversion and Storage. Critical issues in current energy-based societies are its generation through methods utilizing alternatives to fossil fuels as well as its storage. Considering the scope, it is not surprising that the research becomes more and more multidisciplinary. Therefore, it is important to keep focused. The ChemE...
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The role of the nitrogen incorporation into titanium, its chemical nature, the location in the titanium lattice and its electrochemical performance were investigated by a combination of several spectroscopy and microscopy techniques using samples prepared by CVD of NH3 at different temperatures and successive electrochemically tested in 1 M of HClO...
Conference Paper
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The surface of functional materials like catalysts responds to the ambient conditions. X-ray photoelectron spectroscopy (XPS) and soft X-ray absorption spectroscopy (XAS) are one of the most versatile methods for the investigation of surfaces on the atomic scale providing quantitative information about the elemental composition and chemical specifi...
Conference Paper
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A knowledge-based approach towards developing a new generation of solar energy conversion devices requires a fast and direct feedback between sophisticated analytics and state-of-the-art processing/test facilities for all relevant material classes. A promising approach is the coupling of synchrotron-based X-ray characterization techniques, providin...
Conference Paper
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One of the main goals in electrochemistry is the characterization of electrode-electrolyte interfaces under operating conditions, to capture their electronic structure and chemical composition when in contact with the electrolyte and in the presence of applied electrical bias. However, the lack of surface sensitive techniques able to monitor the el...
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We report on the demonstration of ferromagnetic spin injectors for spintronics which are protected against oxidation through passivation by a single layer of graphene. The graphene monolayer is directly grown by catalytic chemical vapor deposition on pre-patterned nickel electrodes. X-ray photoelectron spectroscopy reveals that even with its monoat...
Conference Paper
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The activation of gold in catalytic reactions is a topic of intensive research yielding a good catalyst with excellent activity and selectivity. The electrochemical activation of Au by means of electrodeposited transition metals of fourth row was investigated. Their activity and chemical characterization was performed by means of in situ XAS-FY rev...
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Spatial coupling during catalytic ignition of CO oxidation on μm-sized Pt(hkl) domains of a polycrystalline Pt foil has been studied in situ by PEEM (photoemission electron microscopy) in the 10(-5)mbar pressure range. The same reaction has been examined under similar conditions by FIM (field ion microscopy) on nm-sized Pt(hkl) facets of a Pt nanot...
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This work highlights the importance of in situ experiments for an improved understanding of graphene growth on copper via metal-catalyzed chemical vapor deposition (CVD). Graphene growth inside the chamber of a modified environmental scanning electron microscope under relevant low-pressure CVD conditions allows visualizing structural dynamics of th...
Article
Producing propene by the oxidative dehydrogenation of propane (ODH) has become an attractive and feasible route for bridging the propene production-demand gap, either as a complementary route of the existing oil-based processes or as a new alternative from propane separated from natural gas. The industrial application of propane ODH has not succeed...
Article
Geometric and electronic properties of the K[VO(O-2)Hheida] complex, which serves as a functional model for vanadium haloperoxidase enzymes, as well as of the molecular ions (VO(O-2)Hheida)(-) and (VO(O)Hheida)(-) are evaluated using density-functional theory (DFT). Theoretical results of equilibrium structures, vibrational excitations, oxygen 1s c...
Article
The structures of different titania, vanadia, and vanadia–titania clusters located on the surface of mesoporous silica SBA-15 are optimized using density functional theory (DFT). The apparent absorption spectra arising from these clusters are calculated with the aid of the ORCA package. The silica support is shown to contribute to the absorption sp...
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The morphology, crystallinity, and chemical state of well-defined Ir oxide nanoscale thin-film catalysts prepared on Ti substrates at various calcination temperatureswere investigated. Special emphasiswas placed on the calcination temperature-dependent interaction between Ir oxide film andTi substrate and its impact on the electrocatalytic oxygen e...
Article
Based on our newly developed microwave cavity perturbation technique the electrical conductivity (i.e. catalyst-substrate charge transfer) of vanadium oxide and phosphate catalysts is studied under reaction conditions for the selective oxidation of ethane, propane and n-butane. The conductivity response on temperature, gas phase, gas flow and time...
Article
Simplified IrOx electrodes lacking typical mud crack structure have been produced on polycrystalline Ti cylinders with spin-coating using an iridium acetate solution and are compared to thicker samples in terms of stability, composition, and suitability as a model system. The spin-coating process forms smooth, thin islands of IrOx with limited crac...
Article
Using pulsed EPR and ENDOR, the full set of g matrix and vanadium hyperfine parameters of the persistent paramagnetic V4+ center in "as prepared" and H-2 reduced SBA-15 supported VOx catalysts has been measured. The determination of relative signs of the vanadium hyperfine tensor elements by ENDOR using orientation selection allowed an unambiguous...
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of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
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of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
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The mechanism of the reaction of NO with ashless carbon black was studied in detail. The differences between the amounts of oxygen and nitrogen measured and the calculated concentrations of oxygen and nitrogen suggest the formation of surface carbon–oxygen complexes C(O) and carbon–nitrogen complexes C(N). The dependence of the specific rate of rea...
Article
The role of artificially created defects and steps in the local reaction kinetics of CO oxidation on the individual domains of a polycrystalline Pd foil was studied by photoemission electron microscopy (PEEM), mass spectroscopy (MS), and scanning tunneling microscopy (STM). The defects and steps were created by STM-controlled Ar(+) sputtering and t...
Article
Current methods allow quantitative local structure determination of adsorbate geometries on surfaces in ultrahigh vacuum (UHV) but are incompatible with the higher pressures required for a steady-state catalytic reactions. Here we show that photoelectron diffraction can be used to determine the structure of the methoxy and formate reaction intermed...
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The effect of silicon oxide surface segregation on the locally-resolved kinetics of the CO oxidation reaction on individual grains of a polycrystalline Pd foil was studied in situ by PEEM, MS and XPS. The silicon oxide formation induced by Si-impurity segregation at oxidizing conditions, was monitored by XPS and its impact on the global and local (...
Article
Self-sustained oscillations in the propane oxidation over a nickel foil were studied in situ with the use of ambient-pressure X-ray photoelectron spectroscopy (XPS) coupled with on-line mass-spectrometry and gas chromatography (GC). Regular oscillations of a relaxation type were observed at 0.5 mbar in the temperature range of 600–750 °C in oxygen-...
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Oxygen core excitations in different molecular titania–silica model clusters are evaluated using density-functional theory (DFT). These results are compared with in situ X-ray absorption fine structure (NEXAFS) measurements near the O K-edge of titania model catalysts supported on mesoporous silica, SBA-15, with low Ti loading. The comparison allow...
Article
Our recent surface characterization studies of extended and nanosized PtCo alloys under hydrogen and oxygen atmospheres, indicated significant and reversible surface segregation in response to the gas phase environment [ J. Phys. Chem. Lett. 2011, 2, 900]. In the present communication, an insight into the effect of the support on the PtCo alloy sta...
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Replacing noble metals in heterogeneous catalysts by low-cost substitutes has driven scientific and industrial research for more than 100 years. Cheap and ubiquitous iron is especially desirable, because it does not bear potential health risks like, for example, nickel. To purify the ethylene feed for the production of polyethylene, the semi-hydrog...
Article
We report on the growth of single-walled carbon nanotubes from a monometallic Co catalyst on an oxidized Si wafer support by the most simple growth recipe (vacuum annealing, growth by undiluted C2H2). Nevertheless, multiwavelength Raman spectroscopy and transmission electron spectroscopy show a remarkable selectivity for chiral indices and thus, e....
Article
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The active phase of a bulk metallic copper catalyst is investigated by surface sensitive X-ray absorption spectroscopy at the oxygen K-edge and the Cu L-edges in the total electron yield mode under practical steady state flow-through conditions. The active catalyst surface contains oxygen atoms revealing significant spectral differences compared to...
Article
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The possible role of ammonia in a future energy infrastructure is discussed. The review is focused on the catalytic decomposition of ammonia as a key step. Other aspects, such as the catalytic removal of ammonia from gasification product gas or direct ammonia fuel cells, are highlighted as well. The more general question of the integration of ammon...
Article
The partial substitution of Co by Ru in lanthanum cobaltite perovskites (LaCo1−xRuxO3, x = 0.05 and 0.2) and its influence on the reducibility and structural modifications in the perovskite lattice have been evaluated by N2 adsorption isotherms, in situ X-ray diffraction (XRD), temperature-programmed reduction (TPR) and X-ray photoelectron spectros...
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The locally-resolved reaction kinetics of CO oxidation on individual (100)-type grains of a polycrystalline Pt foil was monitored in situ using photoemission electron microscopy (PEEM). Reaction-induced surface morphology changes were studied by optical differential interference contrast microscopy and atomic force microscopy (AFM). Regions of high...
Article
Oxygen core excitations in different molecular molybdena–silica models are evaluated using density-functional theory (DFT). These results can be compared with in situ X-ray absorption fine structure (NEXAFS) measurements near the O K-edge of molybdena model catalysts supported on SBA-15 silica, used for exploratory catalytic activity studies. The c...
Article
The growth of high density vertically aligned carbon nanotube forests on conductive CoSi2 substrate layers is characterized by in situ x-ray photoemission spectroscopy and x-ray diffraction. We use in situ silicidation to transform as loaded, low conductivity CoSi supports to highly conductive CoSi2 during nanotube growth. These cobalt silicide fil...
Article
AbstractThe reaction kinetics of catalytic CO oxidation on individual grains of a polycrystalline Pt foil has been studied simultaneously by photoemission electron microscopy (PEEM) and mass spectroscopy (MS), in the pressure range ~10−5mbar. By processing the video-PEEM images of ongoing catalytic reaction, the kinetic transitions were tracked for...
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The Publisher regrets that this article is an accidental duplication of an article that has already been published, doi:10.1016/j.cattod.2010.11.051. The duplicate article has therefore been withdrawn.
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The superconducting properties of several binary and ternary fullerene compounds are investigated by means of ac susceptibility technique. The susceptibility X = X'-iX” is observed as a function of temperature for different magnetic field amplitudes (0.01 G - 20 G). The samples are characterized by X-ray diffraction (XRD) analysis and the fcc-latti...
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Prompted by earlier work showing that graphite intercalation compounds form superconducting ternary compounds in which thallium plays an important role C60 has been doped with Tl-alloys. Results of dc-magnetization, ac-susceptibility, X-ray analysis and NMR investigations will be presented. How to Cite This Article Link to This Abstract Blog Thi...
Article
Production of the industrial chemical propylene oxide is energy-intensive and environmentally unfriendly. Catalysts based on bulk silver surfaces with direct propylene epoxidation by molecular oxygen have not resolved these problems because of substantial formation of carbon dioxide. We found that unpromoted, size-selected Ag3 clusters and ~3.5-nan...
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We report the application of commercial carbon nanotubes (CNTs) in two important heterogeneously catalyzed reactions, i.e., NH3 decomposition and oxidative dehydrogenation of ethylbenzene (EB). For NH3 decomposition, CNTs were used as supports for Co–Mo nanoparticles. The structure of fresh and used catalysts was characterized by X-ray diffraction...
Article
The characteristics and reactivity of two anodes based on Pt supported on carbon nanotubes (CNTs) without or with defects induced by ball-milling are studied by SEM, TEM, cyclic voltammetry (CV) and single-cell measurements using a flow of pure H2 or containing 50 ppm CO. It is evidenced that the presence of defects influences several properties an...
Article
Carbon nanofibers were obtained by thermo-catalytic decomposition of methane at 700 degrees C over Ni and Ni-Cu catalysts prepared by different methods (co-precipitation, impregnation and fusion) and using either Al or Mg as textural promoter. Characterization of the carbon thus obtained was performed by N2 adsorption isotherms (BET surface area),...
Article
The structurally well-defined intermetallic compound PdGa – a highly selective catalyst for the semi-hydrogenation of acetylene – was characterized by Fourier transform infrared spectroscopy (FTIR) in situ X-ray photoelectron spectroscopy and in situ prompt gamma activation analysis. A strong modification of the electronic states in PdGa compared t...
Article
Unsupported and SiO2 supported GePt bimetallic catalysts were prepared by depositing Ge on to Pt underpotentially. Surface-sensitive cyclic voltammetry of Pt black indicated that Ge covered ca. 40-45 % of the Pt surface, whereas XPS showed just ~96 % Pt and ~4 % Ge (normalized to Pt+Ge=100 %). High-resolution Ge map of GePt black obtained by Energy...
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The catalytic partial oxidation of methane on platinum was studied in situ under atmospheric pressure and temperatures between 1000 and 1300 °C. By combining radical measurements using a molecular beam mass spectrometer and threshold ionization with GC, GC–MS and temperature profile measurements it was demonstrated that a homogeneous reaction pathw...
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In this study we combine density-functional theory (DFT) calculations on oxygen core excitations in vanadia-silica model clusters with experi-mental in situ X-ray absorption fine structure (NEXAFS) near the oxygen K edge of vanadia model catalysts supported by SBA-15 silica in order to identify structural details of the vanadia species. The silica...
Article
An attempt to measure integral molar extinction coefficients (IMEC) of C-H and C=C stretching bands of propene specifically adsorbed by Na+, Ca2+ and Mg2+ cations in Y zeolite was carried out via parallel IR spectroscopic and volumetric measurements. Propene was adsorbed at low pressures (< 0.5 mbar) on self-supporting wafers pressed from the zeoli...
Article
The NH3 + O2 reaction on a Pt(533) surface has been studied in the 10−4 mbar range and close to 1 mbar pressure with in situ X-ray photoelectron spectroscopy using synchrotron radiation. The coverages of the various O- and N-containing surface species have been followed in T-cycling experiments with varying mixing ratios O2/NH3 and varying total pr...