A5032311312- Electrocatalysts for Energy Conversion
- CO2 Reduction Techniques and Catalysts
- Surface and Thin Film Phenomena
- Electrochemical Analysis and Applications
- Advanced Chemical Physics Studies
- Molecular Junctions and Nanostructures
- Catalytic Processes in Materials Science
- Physics of Superconductivity and Magnetism
- Advanced Materials Characterization Techniques
- Catalysis and Oxidation Reactions
- Force Microscopy Techniques and Applications
- Catalysts for Methane Reforming
- Advanced battery technologies research
- nanoparticles nucleation surface interactions
- Ionic liquids properties and applications
- Quantum, superfluid, helium dynamics
- Spectroscopy and Quantum Chemical Studies
- Catalysis and Hydrodesulfurization Studies
- Quantum and electron transport phenomena
- Fuel Cells and Related Materials
- Advanced Memory and Neural Computing
- Metalloenzymes and iron-sulfur proteins
- Chalcogenide Semiconductor Thin Films
- Analytical Chemistry and Sensors
- Electrodeposition and Electroless Coatings
Technical University of Denmark
2006-2022
Aarhus University
1997-2007
Arizona State University
1997-1999
Forschungszentrum Jülich
1994-1997
Centre d’Immunologie de Marseille-Luminy
1993
Centre National de la Recherche Scientifique
1993
The identification of the active sites in heterogeneous catalysis requires a combination surface sensitive methods and reactivity studies. We determined site for hydrogen evolution, reaction catalyzed by precious metals, on nanoparticulate molybdenum disulfide (MoS 2 ) atomically resolving this catalyst before measuring electrochemical activity solution. By preparing MoS nanoparticles different sizes, we systematically varied distribution Au(111), which quantified with scanning tunneling...
The electrochemical hydrogen evolution reaction is catalyzed most effectively by the Pt group metals. As H2 considered as a future energy carrier, need for these catalysts will increase and alternatives to scarce expensive be needed. We analyze ability of different metal surfaces enzymes nitrogenase hydrogenase catalyze find necessary criterion high catalytic activity. that binding free atomic catalyst close zero. enables us search new catalysts, inspired active site, we MoS2 nanoparticles...
Oxygen evolution was investigated on model, mass-selected RuO2 nanoparticles in acid, prepared by magnetron sputtering. Our investigations include electrochemical measurements, electron microscopy, scanning tunneling microscopy and X-ray photoelectron spectroscopy. We show that the stability activity of nanoparticulate is highly sensitive to its surface pretreatment. At 0.25 V overpotential, catalysts a mass up 0.6 A mg-1 turnover frequency 0.65 s-1, one order magnitude higher than current...
The one-dimensional diffusion of Pt adatoms in the missing row troughs $(1\ifmmode\times\else\texttimes\fi{}2)$ reconstructed Pt(110) surface is monitored directly from atomically resolved time-lapsed scanning tunneling microscopy images. For this self-diffusion system, it surprisingly found that not only jumps between nearest neighbor sites but also long jumps, i.e., next sites, participate. hopping rate for these to follow an Arrhenius dependence with activation barrier...
We have studied the electrochemical reduction of CO2 on Cu overlayers Pt(111) and Pt(211) surfaces. These systems were chosen to investigate effect strain catalytic activity surfaces obtain information about role steps in this process. The selectivity toward hydrocarbons copper is much lower than polycrystalline due a higher for hydrogen evolution. With aim understanding electroreduction overlayers, we also under reaction condition using scanning tunneling microscopy (EC-STM). In presence...
Abstract An understanding of the influence structural surface features on electrocatalytic reactions is vital for development efficient nanostructured catalysts. Gold most active and selective known electrocatalyst reduction CO 2 to in aqueous electrolytes. Numerous strategies have been proposed improve its intrinsic activity. Nonetheless, atomistic knowledge nature sites remains elusive. We systematically investigated structure sensitivity Au single crystals reduction. Reaction kinetics...
A critical step toward the systematic development of electrocatalysts is determination microscopic structure and processes at electrified solid/electrolyte interface. The major challenges this end for experiment computations are achieving sufficient cleanliness modeling complexity electrochemical systems, respectively. In sense, benchmarks well-defined model systems sparse. This work presents a rigorous joint experimental-theoretical study on single-crystal (SC) Cu/aqueous Within typical...
Single and polycrystalline Cu electrodes serve as model systems for the study of electroreduction CO2 , CO nitrate, or corrosion studies; even so, there are very few reports combining electrochemical measurements with structural characterization. Herein both properties single crystal Cu(1 0 0) in alkaline solutions (0.1 m KOH 0.1 NaOH) investigated. It is demonstrated that pre-treatment plays a crucial role determining their properties. Scanning tunneling microscopy, X-ray photoelectron...
We report on a novel diffusion mechanism for one-dimensional platinum clusters the anisotropic $\mathrm{Pt}\left(110\right)\ensuremath{-}(1\ifmmode\times\else\texttimes\fi{}2)$ surface. The mechanism, which is revealed from atom-resolved, time-lapsed scanning tunneling microscopy movies, entails that end atom of cluster promoted up to next layer, migrates over cluster, and drops down again, resulting in displacement by one lattice spacing. activation barriers ascend descend edges are...
ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTEffect of Dissolved Glassware on the Structure-Sensitive Part Cu(111) Voltammogram in KOHAarti TiwariAarti TiwariDepartment Physics, The Technical University Denmark (DTU), Fysikvej 311, 2800 Kgs. Lyngby, DenmarkMore by Aarti Tiwarihttp://orcid.org/0000-0002-8295-9420, Thomas MaagaardThomas MaagaardDepartment Maagaardhttp://orcid.org/0000-0002-2306-1506, Ib ChorkendorffIb ChorkendorffDepartment Chorkendorffhttp://orcid.org/0000-0003-2738-0325,...
The adsorption of Xe on Pt(111) has been investiaged using scanning tunneling microscopy. At low coverage preferentially adsorbs the upper edge preexisting Pt steps resulting in formation one-dimensional chains atoms. With increasing proceeds with growth compact 2D islands nucleated terraces and at lower step edges, but not adjacent to terraces. This is indicative a repulsive interaction between atoms terrace.
Establishing relationships between the surface atomic structure and activity of Cu-based electrocatalysts for CO2 CO reduction is hindered by probable restructuring under working conditions. Insights into these structural evolutions are scarce as techniques monitoring facets in conventional experimental designs lacking. To directly correlate reconstructions to changes selectivity or activity, development surface-sensitive, electrochemical probes highly desirable. Here, we report...
Chemisorbed iodine adlayers on Au(111) films quartz were studied using scanning tunneling microscopy (STM) at room temperature in air. The was adsorbed by successive deposition of droplets a dilute solution methanol. As function coverage, various adlayer structures obtained. By changing the parameters, either or substrate can be imaged with atomic resolution. In this way, adlattice properties such as periodicity, orientation and local absolute coverage have been characterized high accuracy....
We report on the construction of an ultrahigh vacuum (UHV) scanning tunneling microscope (STM) specially designed for operation in entire range sample temperatures between 10 and 400 K. The is cooled by means a liquid helium continuous-flow cryostat, while supporting manipulator surrounding devices remain at room temperature. This allows rapid variation standard instruments surface preparation analysis STM are contained single UHV chamber. By rotation can be positioned front any these...
Abstract An understanding of the influence structural surface features on electrocatalytic reactions is vital for development efficient nanostructured catalysts. Gold most active and selective known electrocatalyst reduction CO 2 to in aqueous electrolytes. Numerous strategies have been proposed improve its intrinsic activity. Nonetheless, atomistic knowledge nature sites remains elusive. We systematically investigated structure sensitivity Au single crystals reduction. Reaction kinetics...
Scanning tunneling microscopy shows that a nanopattern forms as the $\mathrm{Pt}(110)\mathrm{\text{\ensuremath{-}}}(1\ifmmode\times\else\texttimes\fi{}2)$ surface is exposed to oxygen at room temperature or above. The consists of $[1\overline{1}0]$ oriented O-induced stripes assembling into ($11\ifmmode\times\else\texttimes\fi{}2$) superstructure high O coverage. form because adsorption energy increases by expanding Pt lattice along ridges compared bulk. From interplay with density...
The source area of electron field emission from ultrasharp 〈111〉-oriented tungsten tips terminated by a few (down to one single) atoms is confined the very end tip, thus forming an atomic size source. most remarkable property such tips, angular dispersion emitted beam, measured both qualitatively and quantitatively for well-defined arrangements at tip apex also wide range applied electric fields currents. It shown that only pyramidally shaped emit electrons in sharp beams, with small opening...