https://doi.org/10.1140/epjd/e2011-10529-2
Regular Article
Kinetics of the plasmon optical response of Au nanoparticles/TiO2 catalyst under O2 and H2 followed by differential diffuse reflectance spectroscopy
1
Institut des NanoSciences de Paris, CNRS and UPMC Univ. Paris 6,
UMR 7588, 4 place
Jussieu, case courrier 840, 75252
Paris Cedex 05,
France
2
Laboratoire de Réactivité des Surfaces, CNRS and UPMC Univ. Paris
6, UMR 7197, 4 place
Jussieu, 75252
Paris Cedex 05,
France
3
Instituto de Fisica, Universidad Nacional Autonoma de Mexico,
Mexico D.F.,
Mexico
a
e-mail: yves.borensztein@insp.jussieu.fr
Received:
19
September
2010
Received in final form:
24
January
2011
Published online:
17
May
2011
The changes in the optical properties of Au/TiO2 powder catalyst, prepared by the deposition-precipitation method, are measured in the visible range by use of a home-made diffuse differential reflectance spectrometer, when the ambient atmosphere is switched between H2 and O2. Two main features are observed: (i) a short wavelength one, located between 400 and 600 nm, is shown to be related to the modifications of the plasmon resonance of the 3-dimensional metallic gold particles with mean size around 4 nm, induced by the exposure to oxygen or by its removal; (ii) a second feature, observed at long wavelengths between 600 and 1100 nm, is extremely sensitive to the exposure to oxygen. This optical feature could be due to the presence in the catalyst, either of Au0 clusters of several tens atoms, which are expected to display molecular-like transitions in this optical range, or to specific sites of the Au particles (edge atoms or peripheral atoms at the interface with the TiO2 support), which could be highly reactive to oxygen.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2011