نتایج جستجو برای: alumina nanoparticles

تعداد نتایج: 117787  

2006
S. Guimond M. Abu Haija S. Kaya J. Lu J. Weissenrieder S. Shaikhutdinov H. Kuhlenbeck H.-J. Freund J. Döbler J. Sauer

The information obtained from the characterization of vanadium oxide single crystal surfaces is related to the study of vanadia nanoparticles supported on silica and alumina thin films, model systems for the so-called ‘‘supported monolayer vanadia catalysts’’. It is found that these particles have properties similar to V2O3 surfaces, where the topmost V ions are involved in vanadyl groups and h...

2017
Xinjiang Cui Kathrin Junge Xingchao Dai Carsten Kreyenschulte Marga-Martina Pohl Sebastian Wohlrab Feng Shi Angelika Brückner Matthias Beller

Catalytic hydrosilylation represents a straightforward and atom-efficient methodology for the creation of C-Si bonds. In general, the application of homogeneous platinum complexes prevails in industry and academia. Herein, we describe the first heterogeneous single atom catalysts (SACs), which are conveniently prepared by decorating alumina nanorods with platinum atoms. The resulting stable mat...

2014
Aaron D. Franklin David B. Janes Jonathan Claussen Timothy Fisher Timothy D. Sands Jonathan C. Claussen Timothy S. Fisher

Fields of thin-film porous anodic alumina !PAA" are fabricated within a SiO2 support and on independently addressable underlying metal pads. The underlying metallization provides a means for unique postprocessing to be performed on the PAA fields. Customized postprocessing is demonstrated with the synthesis of single-walled carbon nanotubes !SWCNTs" from an embedded catalyst in the PAA, followe...

2013
Mohammad Eftekhari Yazdi Saeed Dinarvand

In this study, the two-dimensional Magnetohydrodynamic (MHD) boundary layer of stagnation-point flow in a nanofluid in the presence of thermal radiation is investigated. Using a similarity transform, the NavierStokes equations are reduced to a set of nonlinear ordinary differential equations. The similarity equations are solved numerically for three types of nanoparticles, namely copper (Cu), a...

Journal: :Physical chemistry chemical physics : PCCP 2012
Laura Roldán Sabino Armenise Yanila Marco Enrique García-Bordejé

A well attached coating of nitrogen-functionalised carbon nanofibers (N-CNFs) has been prepared on the walls of cordierite monolith channels. It is formed via concurrent decomposition of ethane and ammonia catalysed by nickel nanoparticles dispersed on alumina coated cordierite monolith. N-CNF/monoliths synthesis employing several growth temperatures and NH(3) compositions was exhaustively char...

2015
S. A. Hassanzadeh-Tabrizi

In the present work, Al2O3-CeO2 composite nanopowders were synthesized via co-precipitation method. The sinterability of the synthesized powders was investigated. The results showed that the transformation of transition phases of alumina to α-Al2O3 takes place at 1200 °C. TEM images showed that the powders was composed of nanoparticles in the range of 30−70 nm. The densification of composites s...

2006
H.-J. Freund Fritz Haber

Three case studies to demonstrate the ability to characterize oxidation model catalysts and reactions of these systems at the atomic level are reviewed. Firstly, results on small Au aggregates on a clean MgO(100) surface which are interesting model systems for low temperature oxidation are considered. Secondly oxidative dehydrogenation of methanol on alumina supported Pd is addressed. The probl...

Journal: :Physical review letters 2008
Daniel Mulugeta Ki Hyun Kim Kazuo Watanabe Dietrich Menzel Hans-Joachim Freund

NO dimers adsorbed on alumina supported silver nanoparticles (Ag NPs, radii R approximately 1-6 nm) show decreasing desorption temperatures and complex behavior of photoinduced desorption with decreasing NP size. In particular, for resonant excitation of the (1,0) Mie plasmon at 3.5 eV the photoinduced desorption cross section increases with 1/R, showing a pronounced enhancement (40 times) at R...

2017
Wenpei Gao Massimo Colombo Sheng Dai Shuyi Zhang George Graham Xiaoqing Pan Frederick Reines Hall

The use of closed, electron transparent gas cells to perform in situ scanning/ transmission electron microscopy (S/TEM) now enables visualization of the atomic structure of catalysts at variable temperature in a gas environment, which may be close to real operational conditions [1]. When coupled with energy dispersive spectroscopy (EDS) detector, in situ composition analysis can be achieved at ...

Journal: :Journal of the American Chemical Society 2004
Norbert Magg Javier B Giorgi Martin M Frank Boonchuan Immaraporn Thomas Schroeder Marcus Bäumer Hans-Joachim Freund

Alumina-supported vanadium particles were prepared under ultrahigh vacuum (UHV) conditions and characterized with respect to their structural and CO adsorption properties. As supporting oxide, we used a thin, well-ordered alumina film grown on NiAl(110). This allows the application of scanning tunneling microscopy (STM), infrared reflection-absorption spectroscopy (IRAS), and X-ray photoelectro...

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