A5003997094- Electrocatalysts for Energy Conversion
- Catalytic Processes in Materials Science
- 2D Materials and Applications
- Electronic and Structural Properties of Oxides
- Catalysis and Hydrodesulfurization Studies
- Advanced Chemical Physics Studies
- MXene and MAX Phase Materials
- Nanomaterials for catalytic reactions
- Molecular Junctions and Nanostructures
- Force Microscopy Techniques and Applications
- Graphene research and applications
- Copper-based nanomaterials and applications
- Catalysis and Oxidation Reactions
- Surface and Thin Film Phenomena
- Advanced Photocatalysis Techniques
- nanoparticles nucleation surface interactions
- Surface Chemistry and Catalysis
- CO2 Reduction Techniques and Catalysts
- Ionic liquids properties and applications
- Electrochemical Analysis and Applications
- ZnO doping and properties
- Advanced Materials Characterization Techniques
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Electron and X-Ray Spectroscopy Techniques
Aarhus University
2016-2025
Elettra-Sincrotrone Trieste S.C.p.A.
2021
Universidad de Oviedo
2021
Lawrence Berkeley National Laboratory
2016
Rutherford Appleton Laboratory
2016
Haldor Topsoe (Denmark)
2006-2008
Netherlands Institute for Radio Astronomy
2005-2008
Helmholtz-Zentrum Dresden-Rossendorf
2008
Technische Universität Dresden
2008
We have studied using scanning tunneling microscopy (STM) the atomic-scale realm of molybdenum disulfide ( MoS2) nanoclusters, which are interest as a model system in hydrodesulfurization catalysis. The STM gives first real space images shape and edge structure single-layer MoS2 nanoparticles synthesized on Au(111), establishes new picture active sites nanoclusters. results demonstrate way to get detailed information catalysts general.
By the use of density functional calculations it is shown that edges a two-dimensional slab insulating MoS2 exhibit several metallic states. These edge states can be viewed as one-dimensional conducting wires, and we show they observed directly using scanning tunneling microscopy for single-layer nanoparticles grown on support.
Copper offers unique capability as catalyst for multicarbon compounds production in the electrochemical carbon dioxide reduction reaction. In lieu of conventional catalysis alloying with other elements, copper can be modified organic molecules to regulate product distribution. Here, we systematically study which extent is affected by film thickness and porosity. On a polycrystalline electrode, immobilization porous bipyridine-based films varying thicknesses shown result almost an order...
Nanostructures often have unusual properties that are linked to their small size. We report here on extraordinary chemical associated with the edges of two-dimensional MoS2 nanoclusters, which we show be able hydrogenate and break up thiophene (C4H4S) molecules. By combining atomically resolved scanning tunnelling microscopy images single-layer nanoclusters density functional theory calculations reaction energetics, chemistry can one-dimensional metallic states located at perimeter otherwise...
Atomic force microscopy in the non-contact mode (nc-AFM) can provide atom-resolved images of surface of, principle, any material independent its conductivity. Due to complex mechanisms involved contrast formation nc-AFM imaging, it is, however, far from trivial identify individual atoms or adsorbates AFM images. In this work, we successfully demonstrate how extract detailed information about defects and chemical identity on a metal oxide We make use observation that apex tip be altered...
Supported MoS(2) nanoparticles constitute the active component of important hydrotreating catalysts used for industrial upgrading and purification oil feedstock production fossil fuels with a low environmental load. We have synthesized studied model system catalyst consisting nanoclusters supported on graphite surface in order to resolve number very fundamental questions related atomic-scale structure morphology clusters particular effect substrate some types catalysts. Scanning tunneling...
In hydrodesulfurization (HDS) of fossil fuels, the sulfur levels are reduced by extraction from hydrocarbons through a series catalyzed reaction steps on low-coordinated sites molybdenum disulfide (MoS2) nanoclusters. By means scanning tunneling microscopy (STM), we show that adsorption properties MoS2 nanoclusters toward HDS refractory dibenzothiophene (DBT) vary dramatically with small changes in cluster size. STM images reveal size above threshold value 1.5 nm react hydrogen to form...
MoS2 nanoparticles are proven catalysts for processes such as hydrodesulphurization and hydrogen evolution, but unravelling their atomic-scale structure under catalytic working conditions has remained significantly challenging. Ambient pressure X-ray Photoelectron Spectroscopy (AP-XPS) allows us to follow in-situ the formation of catalytically relevant edge sites in active state. The XPS fingerprint is described by independent contributions Mo3d core level spectrum whose relative intensity...
In this work, we demonstrate direct van der Waals epitaxy of MoS2-graphene heterostructures on a semiconducting silicon carbide (SiC) substrate under ultrahigh vacuum conditions. Angle-resolved photoemission spectroscopy (ARPES) measurements show that the electronic structure free-standing single-layer (SL) MoS2 is retained in these due to weak interaction between adjacent materials. The synthesis based reactive physical vapor deposition technique involving Mo evaporation and sulfurization...
When transition metal sulfides such as MoS2 are present in the single-layer form, electronic properties change fundamental ways, enabling them to be used, e.g., two-dimensional semiconductor electronics, optoelectronics, and light harvesting. The is related a subtle modification of band structure due confinement direction perpendicular sheets, there considerable interest understanding how this can controlled adjusted generate 2D-materials with functional properties. In article we report...
The electronic structure of epitaxial single-layer ${\mathrm{MoS}}_{2}$ on Au(111) is investigated by angle-resolved photoemission spectroscopy. Pristine and potassium-doped layers are studied in order to gain access the conduction band. layer found have a $(1.39\ifmmode\pm\else\textpm\fi{}0.05)\text{ }\text{ }\mathrm{eV}$ direct band gap at $\overline{K}$ with valence top $\overline{\mathrm{\ensuremath{\Gamma}}}$ having significantly higher binding energy than $\overline{K}$. moir\'e...
ZnO is a wide band gap metal oxide with very interesting combination of semiconducting, transparent optical and catalytic properties. Recently, an amplified interest in has appeared due to the impressive progress made nanofabrication tailored nanostructures functional surfaces. However, fundamental principles governing structure even clean low-index surfaces have not been adequately explained. From interplay high-resolution scanning probe microscopy (SPM), X-ray photoelectron spectroscopy...
The dynamics of excited electrons and holes in single layer (SL) MoS$_2$ have so far been difficult to disentangle from the excitons that dominate optical response this material. Here, we use time- angle-resolved photoemission spectroscopy for a SL on metallic substrate directly measure free carriers. This allows us ascertain direct quasiparticle band gap 1.95 eV determine an ultrafast (50 fs) extraction carriers via metal contact with MoS$_2$. process is key importance optoelectronic...
The electronic structure of epitaxial single-layer MoS$_2$ on Au(111) is investigated by angle-resolved photoemission spectroscopy, scanning tunnelling and first principles calculations. While the band dispersion supported close to a free-standing layer in vicinity valence maximum at $\bar{K}$ calculated gap similar that for layer, significant modifications are observed other points two-dimensional Brillouin zone: At $\bar{\Gamma}$, has significantly higher binding energy than free expected...
We present a method for synthesizing large area epitaxial single-layer MoS2 on the Au(111) surface in ultrahigh vacuum. Using scanning tunneling microscopy and low energy electron diffraction, evolution of growth is followed from nanoscale islands to continuous layer. An exceptionally good control over coverage maintained using an approach based cycles Mo evaporation sulfurization first nucleate nanoislands then gradually increase their size. During this process native herringbone...
Abstract Transition metal oxides show great promise as Earth-abundant catalysts for the oxygen evolution reaction in electrochemical water splitting. However, progress development of highly active oxide nanostructures is hampered by a lack knowledge location and nature sites. Here we show, through atom-resolved scanning tunnelling microscopy, X-ray spectroscopy computational modelling, how hydroxyls form from dissociation at under coordinated cobalt edge sites nanoislands. Surprisingly, find...