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Chemical and Electron Beam Reduction of Vanadium Oxides Monitored by EELS and NEXAFS

Published online by Cambridge University Press:  02 July 2020

D.S. Su ,
M. Hävecker ,
M. Willinger  and
R. Schlögl
D.S. Su
Affiliation:
Department of Inorganic Chemistry, Fritz-Haber-Institute, Max-Planck Society, Faradayweg 4-6, D-14195, Berlin, Germany
M. Hävecker
Affiliation:
Department of Inorganic Chemistry, Fritz-Haber-Institute, Max-Planck Society, Faradayweg 4-6, D-14195, Berlin, Germany
M. Willinger
Affiliation:
Department of Inorganic Chemistry, Fritz-Haber-Institute, Max-Planck Society, Faradayweg 4-6, D-14195, Berlin, Germany
R. Schlögl
Affiliation:
Department of Inorganic Chemistry, Fritz-Haber-Institute, Max-Planck Society, Faradayweg 4-6, D-14195, Berlin, Germany
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Abstract

The application of modern transmission electron microscopes (TEM) in catalytic research has accelerated the progress in understanding the mechanism of catalytic reactions. For instance, using environmental TEM, the novel glide shear defect process was revealed as an efficient mechanism for the release of the structural oxygen of vanadyl pyrophosphate in the n-butane oxidation [1]. On the other hand, electron energy-loss spectroscopy (EELS), which is nowadays commercially available on modern TEM, appears unknown in the catalytic community. in fact, core-loss EELS is a powerful tool to identify the chemical state of elements and to study the modification of this sate in various compounds.

Fig.l shows EELS-spectra of various vanadium oxides in which the oxidation state of vanadium varies from 2+ (VO) to 5+ (V2O5). The first two features, marked as V L3 and V L2 edges, are attributed to the excitations from V 2p3/2and V 2p1/2core levels to the unoccupied V 3dstates, respectively.

Type
Novel Microscopy Assisted Ceramic Developments in Materials Scienceand Nanotechnology (Organized by P. Gai and J. Lee)
Information
Microscopy and Microanalysis , Volume 7 , Issue S2: Proceedings: Microscopy & Microanalysis 2001, Microscopy Society of America 59th Annual Meeting, Microbeam Analysis Society 35th Annual Meeting, Long Beach, California August 5-9, 2001 , August 2001 , pp. 440 - 441
Copyright
Copyright © Microscopy Society of America 2001

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References

[1]Gai, P.L., Topics in Catalysis 8 (1999) 97CrossRefGoogle Scholar
[2]Knop-Gericke, A., Hävecker, M., Neisius, T., Schedel-Niedrig, T., Nucl. Instr. Meth. A 406 (1998)311CrossRefGoogle Scholar