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  4. Iron Resonant Photoemission Spectroscopy on Anodized Hematite Points to Electron Hole Doping during Anodization
 
research article

Iron Resonant Photoemission Spectroscopy on Anodized Hematite Points to Electron Hole Doping during Anodization

Braun, Artur
•
Chen, Qianli
•
Flak, Dorota
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2012
Chemphyschem

Anodization of a-Fe2O3 (hematite) electrodes in alkaline electrolyte under constant potential conditions the electrode surface in a way that an additional current wave occurs in the cyclic voltammogram. The energy position of this current wave is closely below the potential of the anodization treatment. Continued cycling or exchanging of the electrolyte causes depletion of this new feature. The O 1s and Fe 2p core-level X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra of such conditioned hematite exhibit a chemical shift towards higher binding energies, in line with the general perception that anodization generates oxide species with dielectric properties. The valence band XPS and particularly the iron resonant valence band photoemission spectra, however, are shifted towards the opposite direction, that is, towards the Fermi energy, suggesting that hole doping on hematite has taken place during anodization. Quantitative analysis of the Fe 2p resonant valence band photoemission spectra shows that the spectra obtained at the Fe 2p absorption threshold are shifted by virtually the same energy as the anodization potential towards the Fermi energy. The tentative interpretation of this observation is that anodization forms a surface film on the hematite that is specific to the anodization potential.

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Type
research article
DOI
10.1002/cphc.201200074
Web of Science ID

WOS:000307841900011

Author(s)
Braun, Artur
Chen, Qianli
Flak, Dorota
Fortunato, Giuseppino
Gajda-Schrantz, Krisztina
Graetzel, Michael  
Graule, Thomas
Guo, Jinghua
Huang, Tzu-Wen
Liu, Zhi
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Date Issued

2012

Publisher

Wiley-Blackwell

Published in
Chemphyschem
Volume

13

Issue

12

Start page

2937

End page

2944

Subjects

anodization

•

hematite

•

photoelectrochemistry

•

water splitting

•

X-ray absorption spectroscopy

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LPI  
Available on Infoscience
February 27, 2013
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/89648
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