World Journal Of Engineering
Synthesis and photocatalytic activity of carbon nanomaterials
BASED CdSe COMPOSITES
Mingliang Chen, Zeda Meng, Lei Zhu and Wonchun Oh
Department of Advanced Materials Science & Engineering, Hanseo University, Seosan-si, Chungnam-do, Korea, 356-706
function groups due to it was very stable. 1 g MCPBA was
Introduction
melted in 60 mL Benzene. And then 0.5 g MWCNT was put
Recently, semiconductor nanaoparticles such as TiO2, ZnO
into the oxidizing agent. The mixture was stirred with a
and CdSe quantum dot have been utilized to decorate CNT or
magnet for 6 h at 343 K. Then the MWCNT was dried at 373
graphene nanosheets to prepared carbon nanomaterials-based
K and spared.
materials with remarkable optical and photovoltaic properties
The same amount of graphene oxide and functionalized
[1]. Cadmium selenide (CdSe) is a kind of semiconductor
MWCNT were mixed with Cd(NH3)42+ solution and
with forbidden zone of 1.7 eV, and its valence electrons can be
Na2SeSO3 solution which prepared at above and the mixtures
easily evoked to conduction band when the light wavelength
were stirred and refluxed for at least 5 h, respectively. After
of evoking light is less than or equal to 730 nm. In addition,
the temperature of the mixtures were brought down to room
CdSe is good photocatalyst as a result of the rapid generation
temperature and the mixtures were filtered through What-man
of electron-hole pairs by photo-excitation and the highly
filter paper. The solids obtained were collected and washed
negative reduction potentials of excited electrons [2].
with distill water for 5 times. After being dried in vacuum at
Functionalizing CNT and graphene anaosheets with CdSe not
353 K for 8 h, the Graphene-CdSe composite and CNT-CdSe
only can combine these advantages of CdSe and CNT and
composite were obtained.
graphene nanosheets but also may result in new properties.
Hence, we used multi-walled carbon nanotube (MWCNT) and
Results and Discussions
graphene as carbon nanomaterials to synthesis of carbon
Fig.
nanomaterials-CdSe composites. The photocatalytic activity
Graphene-CdSe composite and CNT-CdSe composite. For
of the as-synthesized samples was evaluated by degrading
CdSe compound, the XRD diffraction peaks around 2θ of
methylene blue (MB) under irradiation of visible light.
25.4°, 42° and 49.6°, which can be indexed to the
1
shows
X-ray
patterns
of
CdSe
compound,
characteristic peaks (111), (220), and (311) plane reflections
of cubic crystal structure CdSe with lattice constants of 6.05 Å
Experimental
For the synthesis of CdSe compound, the sodium seleno
2+
sulfite (Na2SeSO3) solution and Cd(NH3)4
according to the standard powder diffraction data (JCPDS No.
solution was
65-2891 for CdSe, cubic) [3]. However, for Graphene-CdSe
prepared at first. Na2SO3 (5 g) and Selenium metal powder
composite and CNT-CdSe composite, only the typical peaks
(0.5 g) were dissolved in 30 mL distilled water and refluxed
arose from CdSe were detected. The (002) and (100)
for
Meanwhile,
reflection around 2θ of 25.9° and 42.7° due to graphene
Cd(CH3COO)2 (0.5 g) was dissolved in 2 mL distilled water.
overlaps the cubic (111) and (200) reflection around 2θ of
NH4OH (6 mL) was added to it and the mixture was stirred till
25.4° and 42° of CdSe.
1
h
to
form
Na2SeSO3
solution.
2+
it dissolved completely to form Cd(NH3)4
Cd(NH3)4
2+
solution. Finally,
600
solution and Na2SeSO3 solution were mixed
CdSe
Graphene-CdSe
CNT-CdSe
(111)
550
500
together and the mixture was stirred and refluxed for at least 5
Intensity (Counts)
450
h. After the temperature of the mixture was brought down to
room temperature and the mixture was filtered through
(220)
400
350
300
(311)
250
200
150
What-man filter paper. The solid obtained was collected and
100
50
washed with distill water for 5 times. After being dried in
0
10
20
30
40
50
60
70
80
o
2-Theta ( )
vacuum at 353 K for 8 h, the CdSe compound was obtained.
MWCNTs had to functionalize by MCPBA to introduce active
Fig. 1 XRD patterns of CdSe compound, Graphene-CdSe composite
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World Journal Of Engineering
in aqueous solution rather than the CdSe particles for high
and CNT-CdSe composite.
MB concentration, which can reduce the efficiency of the
Fig. 2 shows the TEM image of Graphene-CdSe composite
catalytic reaction. However, for Graphene-CdSe composite
and CNT-CdSe composite, from which, it can be clearly
and CNT-CdSe composite, a much excellent photocatalytic
observed that the CdSe particles are homogenously coated on
activity toward the photodegradation of MB solution can be
the surface of 2D structure grapheme for Graphene-CdSe
observed and the MB concentration is removed 55% after
composite. For CNT-CdSe composite, the surface of
irradiation under visible light for 240 min. The high activity
MWCNTs has been coated with CdSe layers uniformly with
can be attributed to the synergetic effects of high electron
particle size of about 10 nm.
absorptivity
and
high
charge
mobility
of
carbon
nanomaterials.
(a)
(b)
Relative concentration of MB (c/c0)
1.0
0.8
0.6
0.4
CdSe
Graphene-CdSe
CNT-CdSe
0.2
0.0
0
30
60
90
120
150
180
210
240
Irradiation time under visible light (min)
Fig. 2 TEM images of Graphene-CdSe composite and CNT-CdSe
composite.
Fig. 3. Degradation of MB solution under visible light irradiation for
the
CdSe
compound,
Graphene-CdSe
composite
and
The UV-vis diffuse reflectance spectra of CdSe compound,
CNT-CdSe composite. The MB concentration is 5×10-5
Graphene-CdSe composite and CNT-CdSe composite at
mol/L.
wavelength from 400 nm to 1100 nm. The reflectance
characteristics of the CdSe compound were quite similar to
Conclusions
that of the Graphene-CdSe composite and CNT-CdSe
High purity carbon nanomaterials-CdSe composites were
composite except the CdSe compound has an absorption edge
prepared by a simple hydrothermal method. Typical cubic
at 830 nm. Substituting the critical wavelength of CdSe=830
CdSe structure can be observed in XRD patterns of all of
nm into the Planck equation (E=hv), the band gap energy of
carbon nanomaterials-CdSe composites. From the TEM
CdSe is 1.74 eV, which is fairly close to literature value of
results, for graphene-CdSe composite, spherical-shaped
1.65 to 1.8 eV (CdSe) [2]. Moreover, the prepared samples
agglomerated CdSe particles are homogenously coated on the
exhibit strong absorption in the visible light region with
surface of 2D structure grapheme for Graphene-CdSe
wavelength at 400-800 nm, assigned to the band adsorption of
composite. For CNT-CdSe composite, the surface of
CdSe.
MWCNTs has been coated with CdSe layers uniformly with
The photocatalytic activities of the prepared samples were
particle size of about 10 nm. The carbon nanomaterials-CdSe
evaluated by the photodegradation of MB aqueous solution
composites show a higher absorption under visible light
under visible light irradiation. The decreasing concentration of
region comparing with CdSe compound. The MB degradation
MB in the photocatalytic reaction was used to evaluate the
results suggest the carbon nanomaterials-CdSe composites are
activity of the composite. Fig. 3 represents the degradation of
much more effective photocatalyst than CdSe compound. The
MB over CdSe compound, Graphene-CdSe composite and
high activity can be attributed to the synergetic effects of high
CNT-CdSe composite under visible light irradiation, from
electron absorptivity and high charge mobility of carbon
which we can clearly see that the concentration of the MB
nanomaterials.
solution gradually diminish with increasing irradiation time
for all of samples. After irradiation for 240 min, the CdSe
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World Journal Of Engineering
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