Electronic Supplementary Information file for article:
XANES study of Vanadium and Nitrogen dopants in photocatalytic TiO
2
thin films
by
Zakaria El Koura, Giacomo Rossi, Marco Calizzi, Lucia Amidani, Luca Pasquini, Antonio
Miotello, Federico Boscherini
EXPERIMENTAL AND THEORETICAL METHODS
Sample preparation and characterization
Before each deposition, a base pressure of about 10
-7
mbar was achieved in the deposition chamber
of the RF-sputtering and the target was pre-sputtered for 20 minutes to remove all possible
contaminants from the surface. The target-substrate distance was kept constant at 6.0 cm, and the
substrate holder was kept oscillating in the plasma to improve the homogeneity of the films.
X-ray absorption spectroscopy measurements and data analysis
In the measurements at the BM23 beamline, the incident energy was selected using a double bounce
flat crystal Si (111) monochromator. The Vortex Si drift diode detector was placed in the horizontal
plane at right angles to the impinging beam.
The following reference compounds (Ti and V oxides) were measured in transmission mode using
finely ground powders dispersed in polyethylene:
TiO
2
anatase, Alfa Aesar, 99.6% (code: 36199)
TiO
2
rutile, Alfa Aesar, 99.99% (code: 14631)
V
2
O
3
, Sigma-Aldrich, 99.99% (code:463744)
VO
2
, Alfa Aesar, 99% (code: 22957)
V
2
O
5
, Sigma-Aldrich, 99.6 % (code: 221899)
For High Energy Resolution Fluorescence Detected (HERFD) XANES measurements at ID26
beamline, the V K
fluorescence (4952.2 eV) from the samples was selected and focused on an
avalanche photodiode (APD) by five spherically bent (R = 1 m) Ge crystals in (331) reflection. The
incident energy was selected by the Si (311) reflection of a double crystal monochromator, and higher
harmonics were rejected by three Si mirrors under total external reflection.
For the processing of EXAFS spectra using Athena [1], the pre-edge region was fitted with a linear
function while the post – edge region was fitted with a spline to simulate the atomic cross section. As
a first approximation the energy origin for the energy – to – wavenumber conversion ( ) was chosen
0
as the maximum of the first derivative of the absorption spectrum.
Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics.
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