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Synthesis and Photocatalytic Applications of
of TiO2 and its Nanocomposites
Pragati R. Thakur
Department of Chemistry
University of Pune
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Applications of TiO2 in heterogeneous photocatalysis
Limitations of TiO2 as an efficient photocatalyst
Ways to surmount these limitations
Synthesis, characterization and applications of TiO2
Synthesis and applications of composites of TiO2
OUTLINE
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HETEROGENEOUS PHOTOCATALYSIS
Complete mineralization of pollutants to environmentally harmless compounds.
Destruction of non-biodegradable refractory contaminants.
Operate at or slightly above ambient conditions.
Mechanism of Photocatalysis
e -
h +
O2.
Reduction
O2
OH.
Oxidation
H2O
OH. + Pollutants
CO2 + H2O
Schematic representation of the processes occurring in and
on semiconductor particles during the photo-catalytic mineralization
of organic molecules by oxygen.
hR P < 390 nm
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THESE LIMITATIONS CAN BE SURMOUNTED BY
Composite photocatalyst preparation
Metal/Nonmetal doping
LIMITATIONS OF TiO2 AS AN EFFICIENT PHOTOCATALYST
Only active in near UV region
Charge carrier recombination
Low surface area for adsorption
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SYNERGISTIC EFFECT OF CARBON NANOTUBES ON COMPOSIT PHOTOCATALYST
Applied Catal. B: Environ. 2005, 56, 305-312
Environ. Sci. Technol. 2008, 42, 4952-4957
AdsorbentDispersing agent
Large surface area
JMaterial Sci. 2008 43, 2348-2355.
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Preparation of TiO2 nanoparticles
(i) Microemulsion method
(ii) Sol gel method
Characterization of as prepared TiO2 nanoparticles by XRD, FTIR,
DRS, TG-DTA, BET, SEM and TEM.
Application of as prepared TiO2 nanoparticles for the
photocatalytic degradation of targeted pollutant Methyl Orange.
Experimental
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TiO2/activated carbon (TA) composite has been prepared with
enhanced photocatalytic activity by a very simple mechanical
grinding method, which could preserve the respective initial surface
states of the individual solid constituents, giving a synergistic effect.
The as prepared composite was characterized by SEM, XRD, BET
surface area, UV-visible absorbance spectroscopy and Raman
spectroscopy.
p-Nitrophenol was used as target pollutant to test the photocatalytic
activity.
ACTIVATED CARBON-TiO2 COMPOSITE
Synergistic effect of Adsorption and Photocatalysis
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XRD ofMerck TiO2, AC-200 and TA-200(5:1)
Raman spectra
UV-Visible diffuse reflectance
CHARACTERIZATION OF ACTIVATED CARBON-TiO2 COMPOSITE
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Synthesis of Silver Doped TiO2 NanoparticlesSynthesis of Silver Doped TiO2 Nanoparticles
TiOTiO22 nanoparticles were prepared by solnanoparticles were prepared by sol--gel method using Titaniumgel method using Titanium
tetraisotetraiso--propoxide as precursor.propoxide as precursor.
Silver was then photodeposited on the TiOSilver was then photodeposited on the TiO22 Nanoparticles byNanoparticles by
Photodeposition method.Photodeposition method.
Photocatalytic activity was determined by degradation of Methyl OrangePhotocatalytic activity was determined by degradation of Methyl Orange
Dye as target pollutant.Dye as target pollutant.
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a. Ag-TiO2 b. TiO2 c. Merck TiO2
Characterization of Prepared TiO2 and AgCharacterization of Prepared TiO2 and Ag--TiO2TiO2
The XRD pattern shows theThe XRD pattern shows the
presence of pure anatasepresence of pure anatase
phase in TiOphase in TiO22 ..
Solid UVSolid UV--Visible absorbance spectraVisible absorbance spectra
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SEM images of TiOSEM images of TiO22 and Agand Ag--TiOTiO22
TEM images of TiOTEM images of TiO22 and Agand Ag--TiOTiO22
Characterization of Prepared TiOCharacterization of Prepared TiO22 and Agand Ag--TiOTiO22
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AeratorPump
Magnetic Stirrer
Water OutletWater Inlet
Sample Aliquot
Mercury Vapor Lamp
Quartz Tube
EXPERIMENTAL SET UP FOR PHOTOCATALYSIS
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TiO2 Samples BET Surface Area in m2/g
TiO2 microemulsion method
TiO2 Sol-gel method
27.012 0.138 m2/g
150 m2/g
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200 300 400 500 600 700 8000.0
0.2
0.4
0.6
0.8
1.0
Absorbance
wavelength in nm
DiffuseReflectance Spectra ofRT-TiO2 Nanoparicles
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Spectral changes occurred during the photodegradation of MO dye
350 400 450 500 550 600-0.05
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 min.
30 min.
60 min.
90 min.
120 min.
150 min.
Absorbance
wavelength in nm
Spectral changes occurred during
the photodegradation of MO at RT
3 5 0 4 0 0 4 5 0 5 0 0 5 5 0 6 0 0
0 . 0 0
0 . 0 5
0 . 1 0
0 . 1 5
0 . 2 0
0 . 2 5
0 . 3 0
0 . 3 5
0 . 4 0
0 m in.
30 m in .
60 m in .
90 m in .
120 m in .
150 m in .
A
bsorbance
w a v e l e n g t h i n n m
Specta l changes occurred dur ing
the photod egradat ion of M O at RT
T iO2(w ithout surfactant )
3 5 0 4 0 0 4 5 0 5 0 0 5 5 0 6 0 0
0 . 0 0
0 . 0 5
0 . 1 0
0 . 1 5
0 . 2 0
0 . 2 5
0 . 3 0
0 . 3 5
0 . 4 0S p e c t r a l c h a n g e s o c c u r r e d d u r i n g
t h e p h o t o d e g r a d a t i o n o f
M O for w itho ut T iO2
0 m in .
3 0 m in .
6 0 m in .
9 0 m in .
1 2 0 m in .
1 5 0 m in .
A
bsorban
ce
w a ve le n g th in n m
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COD graph of photodegradation of TiO2
0 30 60 90 120
0
10
20
30
40
50
60
70
80
90
%C
D
ti
i
i
i
.
0 30 60 90 120
0
10
20
30
40
%C
D
ti
i i i .
80% COD reduction of TiO2(with
surfactant)41% COD reduction of TiO2 (without
surfactant)
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SEM image of TiO2
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Photocatalytic degradation ofMO dye using TiO2
0 20 40 60 80 100 120 140 1600.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
TiO2
with surfactant
TiO2
without surfactant
without TiO2
/
0
Irradiation time in min.
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XRD pattern of TiO2
2 0 3 0 4 0 5 0 6 0 7 0 8 0
1 0 0
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
B
I
t
ityi
.
U
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FTIR of TiO2
40 00 3 50 0 30 00 25 0 0 20 00 15 0 0 10 00 5 0 0
10
15
20
25
30
35
40
45
B
%
r i-1
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TG-DTA plot of prepared TiO2
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Results and discussion
TiO2 nanoparticles have been synthesized by a reverse microemulsion process using TiCl4
as a precursor and sol-gel method. XRD study shows pure rutile phase for TiO2 prepared by microemulsion method and pure
anatase phase by using sol-gel method.
FTIR study shows strong band for surfactant and broad band corresponding to surface
hydroxyl group on TiO2
TGA shows observable weight loss about 19% and exhaust of HCl gas from the precursor
which is confirmed by chloride test and DTA shows decomposition of hydrated oxide. From DRS calculated band gap energy is 3.0 eV.
BET Analysis shows surface area of microemulsion mediated TiO2 is 27.012 0.138 m2/g
and 150 m2/g for sol-gel method.
TEM images shows spherical shape of TiO2 for both methods.
HigherPhotocatalytic degradation of MO dye has been found for TiO2 prepared by using
surfactant as compared to TiO2 prepared without surfactant.
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REFERENCES
1. Wang Y., Jiang Z., Synthesis of anatase titania-carbon nanotubes nanocomposites with enhanced photocatalytic activity
through a nanocoating-hydrothermal process. J NanoparticleRes. 2007, 9, 1087-1096.
2. Yan J., Song H., Yang S., Yan J., Chen X., Preparation and electrochemical properties of carbon nanotubes loaded with
Ag and TiO2 nanoparticle for use as anode material in lithium-ion batteries. Electrochimica Acta. 2008, 53, 6351-6355.
3. Yu Y., Yu J.C., Chan C.Y., Che Y. K., Zhao J.C., Ding L., Ge W. K., Wong P.K., Enhancement of adsorption andphotocatalytic activity of mesoporous TiO2 by using carbon nanotubes. Appl. Catal. A: Gen. 2005, 289, 186-196.
4.Mishra A., Banerjee S., Sushanta K.M., Graeve O.A.,MishraM., Synthesis of carbon nanotube-TiO2 nanotubular
material for reversible hydrogen storage J. Nanotech. 19, 2008, 445607.
5. Yu H., Quan X., Chen S., Zhao H., TiO2-Multiwalled carbon nanotube heterojunction arrays and their charge
separation capability, J. Phys. Chem. C, 2007, 111, 12987-12991.
6. Rim S., Vittal R., Kim K. J., Incorporation of funtionalized single wall carbon nanotubes in dye sensitized TiO2 solar
cells, Langmuir, 2004, 20, 9807-9810.
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Thank You !