Ex situ chemical synthesis of CoFe2O4-TiO2 nanocomposites
for photodegradation studies
V.B. Shevale a, S.D. Delekar a,b *
a
Department of Chemistry, Shivaji University, Kolhapur 416 001 (MS) India.
b
Department of Chemistry and Biochemistry, Florida State University, Tallahassee 30306
30306-4390 (FL) United States of America.
E-mail addresses:
shevalevrushali@gmail.com,
sddelekar7@rediffmail.com
1. Introduction:
Among various photocatalytic materials, TiO2 (T) is one of the most promising
materials and hence used in various chemical transformations. But due to wide band gap, T
is active in ultraviolet region only, which greatly limits its practical applications. To
enhance its catalytic activity in visible light irradiation, various attempts have been
developed [1]. In the present context, the attempts are made to make the composites of T
with CoFe2O4 (CF), in their varying compositions, for photodegradation of Azaorubine
dye.
2. Materials and Method
All chemicals were of AR grade. Nanocrystalline CF was prepared by sol-gel
auto-combustion method with the stoichiometric amount of metal nitrates, citric acid,
polyethylene glycol (PEG), NH3. Similarly, T nanoparticles were prepared using titanium
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(IV) precursor, acetylacetone, PEG, NH3. These precipitates were filtered, dried and
calcinated at respective temperatures. Then T-CF nanocomposites, with varying
compositions, were synthesized by ex-situ chemical method by using ultra-sonicator.
3. Significant Results and Discussion:
3.1 XRD and FESEM analysis
The composites were consists of tetragonal anatase phase for T particles (JCPDS
No. 84-1285) as well as cubic phase for CF particles (JCPDS No.22-1086 ) with change in
their reflection intensity as per the dominance of the individual materials and also increase
in the crystallite size with increase in CF concentration. XRD patterns are shown in Fig.1.
20
30
(440)
(511)
(400)
40
50
2 (degree)
(203)
(105)
(200)
(004)
(101)
(311)
(004)
Intensity (a. u.)
(220)
(311)
CF
CF (95 %) + T (5 %)
T (95 %) + CF (5 %)
T
60
70
80
Figure 1: XRD of T-CF nanocomposite
FESEM images showed the well defined spherical particles with agglomeration of few
particles.
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Figure 2: FESEM of T-CF nanocomposite
3.2 FTIR analysis
Broad band, in the range of 400-800 cm-1, is ascribed to the Ti-O-Ti stretching
vibrations, while band at 584 cm-1 is due to tetrahedral site of M-O stretching vibrations in
the composites [2].
3.3 UV- vis DRS measurements
The optical band gap of all the samples were calculated using Tauc method [3]
and observed in the range of 3.2 to 2.9 eV.
3.4 Photocatalytic degradation studies
The photocatalytic activity of the T, CF and T-CF samples were evaluated by the
degradation studies of Azorubine S solution in presence of UV or visible light, with
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optimization of various parameters. The kinetic parameters of photodegradation studies are
summarized in the table.1.
Table 1: Photodegradation study
Rate constant (min-1)
Time (min)
60
120
180
240
300
T
CF
3.59 x 10-3
2.90 x 10-3
2.98 x 10-3
3.20 x 10-3
3.65 x 10-3
2.49 x 10-4
2.09 x 10-4
1.88 x 10-4
1.77 x 10-4
1.64 x 10-4
T (95%) + CF
(5%)
2.29 x 10-3
1.30 x 10-3
1.87 x 10-3
2.12 x 10-3
2.33 x 10-3
4. Conclusions:
T-CF nanocomposites were synthesized for photo-degradation of Azorubine under
visible irradiation. The photocatalytic investigation revealed the higher photocatalytic
degradation rate for T-CF ( 95 wt % T + 5 wt % CF ) composites compared than others.
This significant improvement in photocatalytic performance of T-CF ( 95 wt % T + 5 wt %
CF ) composition was mainly attributed to lower band gap energy, and higher surface area.
References:
[1] Li. Li, X. Liu, Y. Zhang, N. T. Nuhfer, K. Barmak, P. A. Salvador, G. S. Rohrer,
Appl. Mater. Interfaces., 5, 2013, 5064-5071.
[2] J. Li, Z. Huang, D. Wu, G. Yin, X. Liao, J. Gu, D. Han, J. Phys. Chem. C.,114,
2010, 1586–1592.
[3] G. Fan, Ji Tong, F. Li, Ind. Eng. Chem. Res., 51, 2012, 13639−13647.
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