Rationally designed laterally-condensed-catalysts deliver robust activity and selectivity for ethylene production in acetylene hydrogenation.

Future carbon management strategies require storage in elemental form, achievable through a sequence of CO hydrogenation reactions. Hydrogen is recycled from molecular intermediates by dehydrogenation, and side product acetylene selectively hydrogenated to ethylene. Existing Pd alloy catalysts for gas purification underperform in concentrated feeds, necessitating novel concepts.

Effect of Iron Doping in Ordered Nickel Oxide Thin Film Catalyst for the Oxygen Evolution Reaction.

Water splitting has emerged as a promising route for generating hydrogen as an alternative to conventional production methods. Finding affordable and scalable catalysts for the anodic half-reaction, the oxygen evolution reaction (OER), could help with its industrial widespread implementation. Iron-containing Ni-based catalysts have a competitive performance for the use in commercial alkaline electrolyzers.

Facet Dependence of the Oxygen Evolution Reaction on CoO, CoFeO, and FeO Epitaxial Film Electrocatalysts.

The main obstacle for the electrocatalytic production of "green hydrogen" is finding suitable electrocatalysts which operate highly efficiently over extended periods of time. The topic of this study is the oxygen evolution reaction (OER), one of the half-reactions of water splitting. It is complex and has intricate kinetics, which impairs the reaction efficiency.

Comparative study of CoO(111), CoFeO(111), and FeO(111) thin film electrocatalysts for the oxygen evolution reaction.

Water electrolysis to produce 'green H' with renewable energy is a promising option for the upcoming green economy. However, the slow and complex oxygen evolution reaction at the anode limits the efficiency. CoO with added iron is a capable catalyst for this reaction, but the role of iron is presently unclear.

Adatom Bonding Sites in a Nickel-Fe O (001) Single-Atom Model Catalyst and O Reactivity Unveiled by Surface Action Spectroscopy with Infrared Free-Electron Laser Light.

Single-atom (SA) catalysis presently receives much attention with its promise to decrease the cost of the active material while increasing the catalyst's performance. However, key details such as the exact location of SA species and their stability are often unclear due to a lack of atomic level information. Here, we show how vibrational spectra measured with surface action spectroscopy (SAS) and density functional theory (DFT) simulations can differentiate between different adatom binding sites and determine the location of Ni and Au single atoms on Fe O (001).

Surface oxygen Vacancies on Reduced Co O (100): Superoxide Formation and Ultra-Low-Temperature CO Oxidation.

The activation of molecular oxygen is a fundamental step in almost all catalytic oxidation reactions. We have studied this topic and the role of surface vacancies for Co O (100) films with a synergistic combination of experimental and theoretical methods. We show that the as-prepared surface is B-layer terminated and that mild reduction produces oxygen single and double vacancies in this layer.

Elucidating Surface Structure with Action Spectroscopy.

Surface Action Spectroscopy, a vibrational spectroscopy method developed in recent years at the Fritz Haber Institute is employed for structure determination of clean and HO-dosed (111) magnetite surfaces. Surface structural information is revealed by using the microscopic surface vibrations as a fingerprint of the surface structure. Such vibrations involve just the topmost atomic layers, and therefore the structural information is truly surface related.

Surface core level BE shifts for CaO(100): insights into physical origins.

The relationship between the electronic structure of CaO and the binding energy, BE, shifts between surface and bulk atoms is examined and the physical origins of these shifts are established. Furthermore, the contribution of covalent mixing to the interaction, including the energetic importance, is investigated and found to be small. In particular, the small shift between surface and bulk O(1s) BEs is shown to originate from changes in the polarizable charge distribution of surface O anions.

Growth of well-ordered iron sulfide thin films.

In this paper a growth recipe for well-ordered iron sulfide films and the results of their characterisation are presented. The film was studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM). XRD data reveal that the film has a NiAs-like structure with Fe vacancies, similar to iron sulfides such as pyrrhotite and smythite, although no indication of any ordering of these vacancies was observed.

Oxidation of Reduced Ceria by Incorporation of Hydrogen.

The interaction of hydrogen with reduced ceria (CeO ) powders and CeO (111) thin films was studied using several characterization techniques including TEM, XRD, LEED, XPS, RPES, EELS, ESR, and TDS. The results clearly indicate that both in reduced ceria powders as well as in reduced single crystal ceria films hydrogen may form hydroxyls at the surface and hydride species below the surface. The formation of hydrides is clearly linked to the presence of oxygen vacancies and is accompanied by the transfer of an electron from a Ce species to hydrogen, which results in the formation of Ce , and thus in oxidation of ceria.

Surface action spectroscopy with rare gas messenger atoms.

Action spectroscopy with inert gas messengers is commonly used for the characterization of aggregates in the gas phase. The messengers, often rare gas atoms or D molecules, are attached to the gas phase aggregates at low temperature. Vibrational spectra of the aggregates are measured via detection of inert gas desorption following a vibrational excitation by variable-energy infrared light.

Vibrational Action Spectroscopy of Solids: New Surface-Sensitive Technique.

Vibrational action spectroscopy employing infrared radiation from a free-electron laser has been successfully used for many years to study the vibrational and structural properties of gas phase aggregates. Despite the high sensitivity of this method no relevant studies have yet been conducted for solid sample surfaces. We have set up an experiment for the application of this method to such targets, using infrared light from the free-electron laser of the Fritz Haber Institute.

Reducing the V2O3(0001) surface through electron bombardment--a quantitative structure determination with I/V-LEED.

The (0001) surface of vanadium sesquioxide, V2O3, is terminated by vanadyl groups under standard ultra high vacuum preparation conditions. Reduction with electrons results in a chemically highly active surface with a well-defined LEED pattern indicating a high degree of order. In this work we report the first quantitative structure determination of a reduced V2O3(0001) surface.

Surface structure of V_{2}O_{3}(0001) revisited.

In a recent paper [A. J. Window et al.

Surface core-level binding energy shifts for MgO(100).

Theoretical and experimental results for the surface core-level binding energy, BE, shifts, SCLS, for MgO(100) are presented and the anomalous O(1s) SCLS is interpreted in terms of the surface electronic structure. While the Mg(2p) surface BE shifts to a higher value than bulk by ≈1 eV as expected from the different surface and bulk Madelung potentials, the O(1s) SCLS is almost 0 rather than ≈-1 eV, expected from the Madelung potentials. The distortion of the surface atoms from the spherical symmetry of the bulk Mg and O atoms is examined by a novel theoretical procedure.

Formaldehyde formation on vanadium oxide surfaces V2O3(0001) and V2O5(001): how does the stable methoxy intermediate form?

Hydroxy-mediated methoxy formation or stabilization is probably an important process in many methanol adsorption systems. Hydrogen atoms originating from the scission of the methanol O-H bond react with the substrate and form water. This process may result 1) in the production of additional surface defects as reactive centers for methoxy formation and 2) in the stabilization of methoxy groups by suppression of methanol formation.