Vladimir V. Roddatis

The Catalytic Use of Onion-like Carbon Materials for Styrene Synthesis by Oxidative Dehydrogenation of Ethylbenzene

-hybridizednanostructuredcarbonhasreceivedincreasingattention both from a fundamental point of view and forpotential applications. A large variety of new fullerene-related materials (giant fullerenes, nanotubes, nanospheres,nanocones, nanofolders, nanobundles, onion-like carbons(OLCs)) have been synthesized.

Carbon Nanofilaments in Heterogeneous Catalysis: An Industrial Application for New Carbon Materials?

Special carbon! Carbon nanofilaments differ from graphite and soot catalysts in their high stability during the oxidative dehydrogenation of ethylbenzene to styrene. The high yields of styrene achieved suggest that a first industrial application of carbon nanofilaments in catalysis is possible.

Large scale synthesis of carbon nanofibers by catalytic decomposition of ethane on nickel nanoclusters decorating carbon nanotubes

A large scale synthesis of carbon nanofibers with a controlled diameter of about 50 nm has been achieved at relatively low temperatures (550–650 °C) by the decomposition of ethane on a carbon nanotube supported nickel catalyst. The carbon nanofibers can be used as a catalyst or a catalyst support without subsequent purification, due to the use of carbon nanotubes as support, the high nanofiber yields, and the purity obtained.

Zwiebelförmige Kohlenstoffe als Katalysatoren in der Styrolsynthese durch oxidative Dehydrierung von Ethylbenzol

Seit der Entdeckung der Fullerene 1985[1] erf‰hrt die Chemie sp2-hybridisierter nanostrukturierter Kohlenstoffe sowohl aus grunds‰tzlichen ‹berlegungen als auch wegen potentieller Anwendungen zunehmendes Interesse. Eine Vielzahl verwandter Materialien wie Riesenfullerene, Nanorˆhren, Nanokugeln, Nanokegel, Nanob ndel oder zwiebelfˆrmige Kohlenstoffe (OLCs, onion-like carbons) wurde synthetisiert.[2] Ihre einzigartigen chemischen und physikalischen Eigenschaften sollten neue Anwendungen ermˆglichen, etwa in den Bereichen Nano-Engineering und -elektronik, f r optoelektronische Sensoren, dreidimensionale Kompositmaterialien, Mikrofilter, magnetische Materialien und in der Katalyse.[3] Die Forschung zu OLCs beschr‰nkt sich zurzeit auf eine Weiterentwicklung der Synthesemethoden und Untersuchung ihrer physikalischen und chemischen Eigenschaften.[4] Wegen ihrer nahezu perfekten graphitischen und trotzdem gespannten Strukturen kˆnnten diese Materialien aus geschlossenen kugelfˆrmigen Kohlenstoffschalen katalytische Eigenschaften aufweisen. folgender Adresse in Gro britannien angefordert werden: Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB21EZ; Fax: ( 44)1223-336-033; oder deposit@ccdc.cam.ac.uk).

The structure of thin zirconia films obtained by self-assembled monolayer mediated deposition: TEM and HREM study

Abstract Transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), and energy dispersive X-ray analysis (EDX) have been performed on thin zirconia films produced by means of self-assembled monolayer (SAM) mediated deposition from aqueous zirconium sulfate dispersion at 50 °C. As-grown films were found to be amorphous. Electron beam irradiation can induce crystallization of the as-grown amorphous zirconia films to tetragonal polycrystalline ZrO 2 films. EELS revealed changes in the oxygen K-edge peak caused by the beam-induced structural transition of the amorphous phase to tetragonal ZrO 2 .

Temperature- and electron-beam-induced crystallization of zirconia thin films deposited from an aqueous medium: A transmission electron microscopy study

Abstract Thin zirconia films prepared by self-assembled monolayer-mediated deposition from an aqueous medium were investigated by transmission electron microscopy and electron-energy-loss spectroscopy. As-grown films were amorphous, and annealing at temperatures below 525°C did not influence the film structure. Annealing at 550°C led to crystallization; amorphous material transformed into the tetragonal phase of ZrO2 (t-ZrO2), yielding a polycrystalline film consisting of 10–50nm sized grains. After annealing at 600°C, a small fraction of monoclinic phase was detected in addition to the tetragonal phase. Sulphur signals were visible in energy-dispersive X-ray spectra of as-grown and of annealed films, with a reduced sulphur content after annealing. Electron-beam irradiation also induced crystallization of amorphous material in as-grown films to give t-ZrO2; in this case the grains forming the polycrystalline film were only 5–10 nm in size.

Tribochemical modification of the microstructure of V2O5

The tribochemical activation of vanadium pentoxide V2O5 is studied by means of X-ray diffraction, electron microscopy and electron energy-loss spectroscopy. The two-stage process can be described as crushing of large crystals into small ones (macroscopic process) followed by amorphisation and reagglomeration of the fragments (microscopic process). No milling equilibrium state can be found. Energy-loss spectra reveal the reduction of vanadium via oxygen loss. The formation and distribution of V4+ or V3+ species depends on the history of milling.

Transmission electron microscopy investigation of Fe3O4 films grown on (111) Pt substrates

Abstract Thin Fe3O4 films prepared by iron deposition and subsequent oxidation on Pt(111) single crystal substrates were studied by selected area electron diffraction and high-resolution transmission electron microscopy (HRTEM). No other iron oxide phases were detected. The formation of Fe3O4 films takes place epitaxially on Pt(111) substrates with the relationships: [111]Pt//[111]Fe3O4, [110]Pt//[110]Fe3O4. The films were free of dislocations but contained antiphase boundaries (APB) between domains shifted by 1.86 or 2.35 A relative to each other along the [111] direction. The lattice mismatch between Fe3O4 and Pt causes periodic arrays of strained regions in the oxide along the interface. The iron oxide lattice parameters near the interface are compressed by approximately 2%. Detailed analysis of the Fe3O4/Pt interface based on HRTEM images and image simulations show that the first layer of the oxide on the Pt substrate consists of iron atoms.