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plays an important role in enlarging or inhibiting the polarisation
5
9
effect . When the metal clusters are too thick for their surface to
be affect by the underlying polarisation, it will behave similarly
to the other nonpolar systems. But in our system, the size of Ag
nanoparticles is only 5-10nm, which is not likely to block the
effect from polarisation, although the exact critical thickness is
not known. Thus the first reason is more likely. Nevertheless, our
initial attempt to probe into the degradation mechanism,
intermediates and pathways in degradation of RhB dye molecules
using ferroelectric BaTiO3 provides a deeper understanding in
ferroelectric catalytic system and add directions to the
development of a new efficient photocatalyst.
(
(
(
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We have used UV-Vis spectroscopy, NMR and GC-MS to
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1
2
2
3
5
0
5
0
simulated solar light with silver modified BaTiO3 as
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photocatalyst. Our results indicate that a tight Stern layer is
formed consisting of the dye cation and counter anions around the
ferroelectric catalyst. The polarisation of the dipole associated
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photosensitized oxidation process between adsorbed dye and the
catalyst, such that we see no evidence of direct electron injection
from the dye into the Ag-BTO. The hypsochromic wavelength
shift of the maximum absorption peak shown by UV-vis
demonstrates that the cleavage of the chromophore structure was
the primary initial process of molecule breakdown. The use of
NMR analysis further supported the hypothesis that during
degradation there was cleavage of the chromophore structure
followed by deethylation of the dye molecule. Analysis of the
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Materials Research Institute, School of Engineering and Materials Science, Queen
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†
Electronic Supplementary Information (ESI) available: [Dye adsoprtion
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conditions, zeta potential of Ag-BTO, photodegradation profiles, reaction
mechanisms, uv-vis spectra and H NMR spectra in P25 system, GC-MS
spectra and identified intermediates in P25 system and the comparsion
with standard compounds ]. See DOI: 10.1039/b000000x/
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