Two dimensional and layered transition metal oxides

http://w0.rz-berlin.mpg.de/hjfdb/pdf/546e.pdf

Monolayer iron oxide film on platinum promotes low temperature CO oxidation

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

In this work, a series of Pd/Fe2O3 catalysts were synthesized, characterized, and evaluated for the hydrodeoxygenation (HDO) of m-cresol. It was found that the addition of Pd remarkably promotes the catalytic activity of Fe while the product distributions resemble that of monometallic Fe catalyst, showing high selectivity toward the production of toluene (C–O cleavage without saturation of aromatic ring and C–C cleavage). Reduced catalysts featured with Pd patches on the top of reduced Fe nanoparticle surface, and the interaction between Pd and Fe, was further confirmed using X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and X-ray absorption near edge fine structure (XANES). A possible mechanism, including Pd assisted H2 dissociation and Pd facilitated stabilization of the metallic Fe surface as well as Pd enhanced product desorption, is proposed to be responsible for the high activity and HDO selectivity in Pd–Fe catalysts. The synergic catalysis derived from P...

Synergistic Catalysis between Pd and Fe in Gas Phase Hydrodeoxygenation of m-Cresol

We have investigated the magnetic and electronic properties of a FeO film grown on Pt(111). Coupling first-principles density-functional theory calculations with scanning tunneling microscopy (STM) measurements we have identified the principal mechanisms for the structural and electronic characteristics observed in the Moire unit cell formed between oxide film and metal support. We show that both free and supported FeO(111) monolayers present an antiparallel alignment of the magnetic moments. Due to the lattice mismatch between Pt(111) and the FeO film, the interface properties are different in different regions of the supercell. The resulting modulation of the structural and electronic properties of the film is determined by the strength of the film-substrate interaction in various regions of the supercell. In particular, for the Fe-top site, where this interaction is weak, there is a small rumpling of the FeO layer which increases the interface separation. In correspondence of this structural modification, we observe a change in the work function, coherent with the most recent experimental findings. Our results show that a good agreement with the experimental interpretation of the work function modulation and of the STM images can be obtained only within the more robust, nonpseudomorphic computational models.

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Interplay between structural, magnetic, and electronic properties in a FeO/Pt(111) ultrathin film

http://w0.rz-berlin.mpg.de/hjfdb/pdf/478e.pdf

Characterization of a Pd–Fe bimetallic model catalyst

The electronic structure around the Fermi energy of a thin film of iron monoxide on Pt(111) is studied using low temperature scanning tunneling spectroscopy. The surface exhibits a coincidence structure (Moir\'e pattern) due to a lattice mismatch between the oxide thin film and the metal substrate. While the local density of states around the Fermi energy is featureless at most positions in the unit cell, a pronounced depression is observed at one particular site. The origin of this local zero-bias anomaly is discussed in relation to results from first-principle calculations. As a preliminary conclusion, it is suggested that the anomaly is a Kondo resonance due to a frustrated antiferromagnetic layer.

/pdf/local-zero-bias-anomaly-in-tunneling-spectra-of-a-transition-2fdyv8mkeh.pdf

Marcella P. Felicissimo

Papers

Characterization of a Pd–Fe bimetallic model catalyst

Local zero-bias anomaly in tunneling spectra of a transition-metal oxide thin film