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Photoinduced reduction of surface states in Fe:ZnO.

Knut, R; Lagerqvist, U; Palmgren, P; Pal, Prabir LU ; Svedlindh, P; Pohl, A and Karis, O (2015) In Journal of Chemical Physics 142(20).
Abstract
We report on the electronic structure of nano-crystalline Fe:ZnO, which has recently been found to be an efficient photocatalyst. Using resonant photoemission spectroscopy, we determine the binding energy of Fe 3d states corresponding to different valencies and coordination of the Fe atoms. The photo-activity of ZnO reduces Fe from 3+ to 2+ in the surface region of the nano-crystalline material due to the formation of oxygen vacancies. Electronic states corresponding to low-spin Fe2+ are observed and attributed to crystal field modification at the surface. These states are potentially important for the photocatalytic sensitivity to visible light due to their location deep in the ZnO bandgap. X-ray absorption and x-ray photoemission... (More)
We report on the electronic structure of nano-crystalline Fe:ZnO, which has recently been found to be an efficient photocatalyst. Using resonant photoemission spectroscopy, we determine the binding energy of Fe 3d states corresponding to different valencies and coordination of the Fe atoms. The photo-activity of ZnO reduces Fe from 3+ to 2+ in the surface region of the nano-crystalline material due to the formation of oxygen vacancies. Electronic states corresponding to low-spin Fe2+ are observed and attributed to crystal field modification at the surface. These states are potentially important for the photocatalytic sensitivity to visible light due to their location deep in the ZnO bandgap. X-ray absorption and x-ray photoemission spectroscopy suggest that Fe is only homogeneously distributed for concentrations up to 3%. Increased concentrations does not result in a higher concentration of Fe ions in the surface region. This is limiting the photocatalytic functionality of ZnO, where the most efficient Fe doping concentration has been shown to be 1%-4%. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Chemical Physics
volume
142
issue
20
publisher
American Institute of Physics
external identifiers
  • pmid:26026457
  • wos:000355919300030
  • scopus:84930669625
ISSN
0021-9606
DOI
10.1063/1.4921570
language
English
LU publication?
yes
id
693edf66-1fbf-43f7-b799-2aa706d2e9bd (old id 7508731)
date added to LUP
2015-07-22 09:27:39
date last changed
2017-09-17 04:00:09
@article{693edf66-1fbf-43f7-b799-2aa706d2e9bd,
  abstract     = {We report on the electronic structure of nano-crystalline Fe:ZnO, which has recently been found to be an efficient photocatalyst. Using resonant photoemission spectroscopy, we determine the binding energy of Fe 3d states corresponding to different valencies and coordination of the Fe atoms. The photo-activity of ZnO reduces Fe from 3+ to 2+ in the surface region of the nano-crystalline material due to the formation of oxygen vacancies. Electronic states corresponding to low-spin Fe2+ are observed and attributed to crystal field modification at the surface. These states are potentially important for the photocatalytic sensitivity to visible light due to their location deep in the ZnO bandgap. X-ray absorption and x-ray photoemission spectroscopy suggest that Fe is only homogeneously distributed for concentrations up to 3%. Increased concentrations does not result in a higher concentration of Fe ions in the surface region. This is limiting the photocatalytic functionality of ZnO, where the most efficient Fe doping concentration has been shown to be 1%-4%.},
  articleno    = {204703},
  author       = {Knut, R and Lagerqvist, U and Palmgren, P and Pal, Prabir and Svedlindh, P and Pohl, A and Karis, O},
  issn         = {0021-9606},
  language     = {eng},
  number       = {20},
  publisher    = {American Institute of Physics},
  series       = {Journal of Chemical Physics},
  title        = {Photoinduced reduction of surface states in Fe:ZnO.},
  url          = {http://dx.doi.org/10.1063/1.4921570},
  volume       = {142},
  year         = {2015},
}