Photodegradation Properties of Dye in TiO2 Nanocomposite

1
Photodegradation Properties of Dye in TiO2
Nanocomposite
J.H. Jeong, C.R. Cho, J.O. Moon, J.H.
Yang, B.K. Moon, S.M. Son, S.T.
Chung Dept. of Electronic Eng. Dept. of
Image and Information Eng. Dept. of
Physics.,Pukyong National Univ., Daeyon 3 Dong,
Nam Gu, Pusan, Korea
2
Purpose of Research
h?
TiO2
TiO2
TiO2
Dye

TiO2

Dye
degradadtion
3
Block Diagram
UVR 6100(Epoxy)
Bis-(4,4'-p-toluenesulfonylacidic
isoproplylidene)-cyclohexadiol(BTSPC)
Squarylium dye
TiOCH(CH3)24
Glove Box
UVI 6990
Spin Coating
ITO and Pyrex glass
XENON LAMP
Thin Films
Fig. Manufacturing process of dye-coated TiO2
thin films
4
Structure and Mechanism
h?
H
O
O
CH3

H
S
CH3
O
S
C
O
CH3
CH3
O
O
H
5
Device
Fig. Structure of dye-coated TiO2 thin films
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Absorbance Spectrum
UV-Vis was measured in a range of 200
800nm With increasing TiO2, absorption peak
shifted to long-wavelength Absorption wavelength
of TiO2 showed at 360nm
Fig. Absorbance spectrum of thin films vs. amount
of TiO2
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(ah?)2 - h? curves
Optical theory was applied to ah?(h?-Eg)0.5,
where a is absorption peak and h? is photon
energy The major absorbance at wavelength below
360nm is corresponding to its energy gap of 3.32eV
Fig. (ah?)2 - h? curve of thin films vs. amount
of TiO2
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AFM Images
(b)
(a)
White parts of Fig.(a) show nanoparticles of
TiO2. Size was approximately 150nm. Fig.(b) shows
surface of TiO2 thin films. Fig.(c) shows
surface of TiO2 thin films of three-dimension and
distribution.
500nm
500nm
(c)
Fig. AFM images of TiO2 thin films in epoxy
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AFM Images
Size of TiO2 was getting smaller
According to TiO2 amount
20
10
30
50
40
Fig. AFM images of TiO2 thin films according to
TiO2 amount in toluene
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Dye-coated TiO2
Absorption peak of dye in the thin films without
TiO2 was 635nm. Absorption peak of dye-coated
TiO2 thin films did not appear in a visible ray
region.
Fig. Comparative absorbance spectrums of
dye-coated TiO2 and dye.
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Time of Irradiation
In the thin films with longer UV light
irradiation time, more obvious photodegradation
of the dye was observed. UV light caused very
rapid TiO2-sensitized photodegradation of the
dye.
Fig. Absorbance spectrum of dye-coated TiO2 thin
films vs. time of irradiation
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Conclusion