Preparation and characterization of Fe3O4/SiO2/CdS nanocomposites as efficient magnetic photocatalysts for the reduction of nitro compounds under visible LED irradiation

Article abstract of DOI:10.1016/j.jphotochem.2018.06.011

A series of magnetic Fe₃O₄/SiO₂/CdS nanocomposites were synthesized through a facile and convenient method. The characterization of the prepared nanocomposites was performed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), vibrating sample magnetometer (VSM), UV–Vis spectroscopy, and UV–vis diffuse reflectance spectroscopy (DRS). The prepared magnetic photocatalysts were first utilized for the photocatalytic reduction of nitro compounds under visible LED irradiation. The Fe₃O₄/SiO₂/CdS nanocomposites exhibited enhanced photoactivity compared with the bare CdS and commercial CdS (Aldrich). The results demonstrated that Fe₃O₄/SiO₂/CdS nanocomposites have potential to provide a promising visible light driven photocatalyst for the selective reduction of nitro compounds to corresponding amines under mild conditions. The prepared photocatalyst can be recovered by magnetic separation and successfully reused for 3 cycles.

Full text of DOI:10.1016/j.jphotochem.2018.06.011

Accepted Manuscript
Title: Preparation and characterization of Fe O /SiO /CdS
3
4
2
nanocomposites as efficient magnetic photocatalysts for the
reduction of nitro compounds under visible LED irradiation
Authors: Parvin Eskandari, Foad Kazemi
PII:
S1010-6030(18)30154-0
DOI:
Reference:
https://doi.org/10.1016/j.jphotochem.2018.06.011
JPC 11328
To appear in:
Journal of Photochemistry and Photobiology A: Chemistry
Received date:
Revised date:
Accepted date:
4-2-2018
3-6-2018
4-6-2018
Please cite this article as: Eskandari P, Kazemi F, Preparation and characterization of
Fe O /SiO /CdS nanocomposites as efficient magnetic photocatalysts for the reduction
3
4
2
of nitro compounds under visible LED irradiation, Journal of Photochemistry and
Photobiology, A: Chemistry (2018), https://doi.org/10.1016/j.jphotochem.2018.06.011
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Preparation and characterization of Fe
3
O
4
/SiO /CdS nanocomposites as
2
efficient magnetic photocatalysts for the reduction of nitro compounds under
visible LED irradiation
a
b,c
Parvin Eskandari , Foad Kazemi *
a
Department of Chemistry, Zanjan Branch, Islamic Azad University, 49195-467, Zanjan, Iran
Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, 49195-1159,
b
Zanjan, Iran
c
Center for Climate and Global Warming (CCGW), Institute for Advanced Studies in Basic Sciences (IASBS), Gava
Zang, 45137-66731, Zanjan, Iran
Tel: 33153219
Fax: 33153232
Email: kazemi_f@iasbs.ac.ir
Graphical Abstract
1

Highlights


Fe
3
O
4
/SiO /CdS photocatalysts were synthesized through a facile and convenient method.
2
The photocatalytic reduction of aromatic nitro compounds to their corresponding amines
was achieved under blue LED (3W) irradiation.


Fe
3
O
4
/SiO /CdS nanocomposite had higher photocalaystic activity than bare CdS and
2
commercial CdS (Aldrich).
The magnetic photocatalyst could be recovered easily using an external magnetic field and
reused three times.
Abstract:
3 4 2
A series of magnetic Fe O /SiO /CdS nanocomposites were synthesized through a facile and convenient method. The
characterization of the prepared nanocomposites was performed by Fourier transform infrared spectroscopy (FT-IR),
X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy
dispersive X-ray (EDX), vibrating sample magnetometer (VSM), UV–Vis spectroscopy, and UV-Vis diffuse
reflectance spectroscopy (DRS). The prepared magnetic photocatalysts were first utilized for the photocatalytic
reduction of nitro compounds under visible LED irradiation. The Fe
photoactivity compared with the bare CdS and commercial CdS (Aldrich). The results demonstrated that
Fe /SiO /CdS nanocomposites have potential to provide a promising visible light driven photocatalyst for the
3 4 2
O /SiO /CdS nanocomposites exhibited enhanced
3
O
4
2
selective reduction of nitro compounds to corresponding amines under mild conditions. The prepared photocatalyst
can be recovered by magnetic separation and successfully reused for 3 cycles.
Keywords: Photocatalysis, Magnetic CdS nanocomposite, Aromatic nitro compounds, LED irradiation
1
. Introduction:
Semiconductor photocatalysis has been gaining increasing attention as the most promising potential for solar energy
conversion and environmental remediation [1-6]. Among various semiconductor photocatalysts, cadmium sulfide
(
CdS), owing to its suitable band gap (2.4 eV), corresponds well to the spectrum of sunlight [7]; and for its size-
2

dependent electronic and optical properties [8] is being considered for the wide range of applications including solar
cells [9-11], biosensors [12], field-effect transistors (FET) [13], and as a photocatalyst [14-18]. In order to control the
size, stabilize, and enhance the visible light activity of semiconductors nanocrystals, numerous papers describe the
deposition and immobilization of nanoparticles on inert materials, such as silica [15], carbon [16, 17], graphene [5,
1
8-21], zeolites [22], and other mesoporous matrices [23]. Among various supporting materials, magnetically
separable nanoparticles have been intensively studied because of their unique properties to facilitate the separation of
photocatalyst from the reaction mixture by simply applying an external magnetic field [24-27]. Recently, some groups
have achieved delightful success in this area; for example, Liu and co-workers have synthesized Fe
nanocomposites that exhibited both fluorescence and photocatalytic activity toward the decomposition of methyl
orange in aqueous solution [14]. Hu and co-workers have synthesized one-dimensional (1D) Fe /C/CdS coaxial
nanochains as highly efficient and recyclable photocatalysts for water treatment [16]. Fe -doped CdS hollow sphere
has been synthesized by combining Fe with nanoparticulate CdS and applied as a photocatalyst in the degradation
of organic dyes [27]. Moreover, TiO based magnetic photocatlysts have been enjoying great research interest for their
potential in photocatalysis [28-32]. In addition, some novel magnetic photocatalytic nanoreactors [33, 34] and a novel
magnetic intercalation Fe -QDs@g-C /ATP photocatalyst have been developed more recently by Zhu et al.
35]. However, the methods in which they have been utilized often involve photocatalytic degradation of pollutants
3 4
O /CdS
3 4
O
3
O
4
3 4
O
2
3O
4
3N
4
[
and water treatment [36-38]. Notably, the photocatalytic reduction of nitro compounds has attracted increasing
attention as it holds great promise for providing an alternative to the conventional synthetic process [17, 18, 39-47].
The required mild conditions and the possibility to decrease the generation of undesired products highlight its potential
as a promising and green technique for selective reduction of nitro compounds to corresponding amines. Through a
literature survey, it can be found that the investigation of magnetic based photocatalysts for photocatalytic selective
organic transformation is very limited. In this paper, the magnetically separable Fe
3
O
4
/SiO
2
/CdS photocatalysts were
prepared via a simple method, using direct loaded CdS on the surface of silica-coated Fe
3
O
4
nanoparticles (Fe /SiO
3
O
4
2
core/shell) to develop novel methods for the photocatalytic reduction of nitro compounds [48-52]. The prepared
nanocomposites were firstly employed as effective and magnetically recyclable photocatalysts in the reduction of
aromatic nitro compounds to their corresponding amines under the blue LED irradiation in a very simple condition.
The results showed that Fe
3
O
4
/SiO
2
/CdS nanocomposites exhibited higher photocatalytic activity than bare CdS and
commercial CdS (Aldrich).
3

2
2
. Experimental Section:
.1. Materials
Chemicals and apparatus: FeCl
3 2 2 2
.6H O, FeCl .4H O, cadmium acetate, 3-(mercaptopropyl) trimethoxysilane
(
MPTMS), and tetraethyl orthosilicate (TEOS) were purchased from Aldrich Co. Ammonia solution (25%), thiourea,
toluene, dimethylformamide (DMF), and acetone were purchased from Merck Co. All reagents were used without
further purification. Deionized water was used in all experiments.
2
.2. Preparation of Fe
3
O
4
/SiO /CdS nanocomposites:
2
Synthesis of Fe
3 4 3 4 2 2
O nanoparticles: In order to prepare Fe O nanoparticles after mixing FeCl .4H O (5.4 g) and
FeCl .6H O (2 g) in 2 M hydrochloric acid (25 mL) solution, ammonia solution [25% (v/v), 40 mL] was added
3
2
dropwise over a period of 30 minutes under vigorous stirring. During the reaction, argon gas was allowed to flow
through the flask. The magnetic nanoparticles were rinsed with deionized water (3×30 mL) and dried at 60 °C for 12
h in a vacuum oven [53].
Synthesis of Fe
3
O
4
/SiO
nanoparticles were dispersed in 50 mL of EtOH and 10 mL deionized water and sonicated for
5 min. 1.5 mL tetraethylorthosilicate (TEOS) was added dropwise and the mixture was sonicated for 10 min. Then
mL of ammonia solution [25% (v/v)] was added dropwise during 10 min. The hydrolysis of TEOS under alkaline
2
nanoparticles: In order to prepare silica coated magnetic cores Fe
3
O
4
/SiO
2
nanoparticles,
2
g of nanosized Fe
3
O
4
1
1
condition was carried out in an ultrasonic bath for 3 h and the mixture was left to stand overnight. The silica coated
particles were separated using an external magnet, washed three times with ethanol, and dried in a vacuum oven at 60
°
C for 12 h [54].
Synthesis of thiolated magnetic nanoparticles: In a typical procedure, 2 mL of 3-(mercaptopropyl) trimethoxysilane
MPTMS) was added to 40 mL of a toluene suspension containing 2 g of Fe /SiO nanoparticles. The mixture was
refluxed for 24 h under constant stirring. The product Fe -SiO PrSH (TMNP) was separated by external magnet,
(
3
O
4
2
3
O
4
2
washed with EtOH, and dried in a vacuum oven at 45 °C for 12 h.
4

3 4 2
Synthesis of Fe O /SiO /CdS nanocomposites: The obtained thiopropyl-coated nanomagnets (TMNP) were subjected
to supporting CdS. 200 mg of TMNP was added to 25 ml of DMF solution, containing different amounts of cadmium
acetate and thiourea (The amount of cadmium acetate : thiourea were 1:1.82, 2:3.75, 4:7.5 mmol). Then the reaction
mixture was exposed to ultrasound for 15 min followed by heating at 135 °C for 15 min. The resulting brownish solids
were magnetically separated, washed with EtOH three consecutive times, and dried in an oven at 45 °C for 12 h.
(
Figure 1) The products obtained with different amounts of cadmium acetate 1, 2, and 4 mmol were named as S1, S2,
and S4 respectively, while Fe /SiO was labeled as S0.
3
O
4
2
Synthesis of bare CdS: 25 mL of a DMF solution containing cadmium acetate (2 mmol) and thiourea (3.75 mmol)
were heated at 135 °C for 15 min. The resulting yellow solids were filtered and washed with EtOH three consecutive
times and dried in an oven at 45 °C for 12 h.
3 4 2
Figure 1. Illustration of the preparation of Fe O /SiO /CdS nanocomposites
The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-
IR), transmission electron microscopy (TEM), UV-Vis spectroscopy, energy dispersive X-ray (EDX), and UV-Vis
diffuses reflectance spectroscopy (DRS). Magnetic properties of the prepared samples were investigated using a
vibrating sample magnetometer (VSM) with an applied field between 10000 and 10000 Oe at room temperature.
2
.3. Photocatalytic activity:
3 4 2
The Fe O /SiO /CdS (S2) with average amount of CdS has been chosen as a photocatalyst for the photocatalytic
reduction of nitro compounds under the blue LED irradiation. In a 10 mL flask, 5 ml of 0.01 M nitro compounds
solution and 0.02 g photocatalyst were charged. Then the flask was charged with pure argon. The resulting mixture
was stirred for 20 h under LED irradiation. After this time, the catalyst was simply separated by employing an external
5

magnetic field and the remaining solution was analyzed using thin-layered chromatography (TLC) and Varian gas
chromatograph (CP-3800). The conversion of nitro substrate, yield of amine, and selectivity for amine were defined
as follows:
0 0
Conversion (%) = (C −Cnitro)/C ×100
0
Yield (%) = Camine/C ×100
0
Selectivity (%) =Camine/(C −Cnitro)×100
0
Where C is the initial concentration of nitro compound and Cnitro and Camine are the concentration of the nitro substrate
and the corresponding amine respectively, after the photocatalytic reaction.
3
. Result and discussion:
In order to prepare the photocatalysts, a known silica-coated nanomagnet was chosen, which can be easily prepared
from cheap starting materials according to the reported procedure with little modification [53, 54]. The resulting
Fe
mercaptopropyl) trimethoxysilane to give thiol-functinalized silica-coated nanomagnets (Fe
end, the obtained thiolpropyl-coated nanomagnets were subjected to react with cadmium acetate and thiourea to form
the Fe /SiO /CdS nanocomposites (TMN-CdS) (Figure 1).
3
O
4
/SiO
2
nanoparticles were then allowed to react under vigorous stirring with an appropriate concentration of (3-
3
O
4
/SiO /PrSH). To this
2
3
O
4
2
The crystal structure of the prepared materials was characterized using XRD pattern and TEM images. The diffraction
patterns of the prepared Fe /SiO /CdS nanocomposites are similar and in good agreement with cubic phase of CdS.
The XRD patterns of TMNP, Fe /SiO /CdS nanocomposites, and bare CdS are shown in Figure 2. All the diffraction
peaks can be indexed to the Fe
3
O
4
2
3
O
4
2
3
O
4
(JCPDS card no.; 75-1609) and cubic phase CdS (JCPDS card no. 10-0454) [14].
6

Figure 2. X-ray powder diffraction patterns of (a) TMNP, (b) S4, (c) S2, (d) S1, and (e) bare CdS
The morphology of the Fe /SiO /CdS nanocomposites was examined by SEM. An overview of the images for the
3
O
4
2
prepared samples demonstrates that the product consists of small nanostructures. The SEM image of TMN-CdS (S2)
is shown in Figure 3a. The TEM image of the same sample (Figure 3b) indicates that the average size of the
nanostructures is less than 40 nm. The energy dispersive X-ray spectroscopy (EDX) analysis of TMN-CdS
nanocomposites confirmed the presence of the elements Cd, S, Fe, and Si (Figure 4). Additionally, the EDX results
indicates that the wt % of Cd and S increased by increasing the amount of CdS precursors. The FT-IR spectrum of the
3 4 2
prepared samples showed peaks that are characteristic of Fe O /SiO /CdS nanocomposites, which clearly differ from
those of the unfunctionalized silica coated nanomagnets and thiol functionalized magnetic nanoparticles. This
analysis, in combination with XRD and EDX data, indicated the successful anchoring of the CdS particles on the
surface of magnetic nanoparticles.
Figure 3. SEM (a) and TEM (b) images of Fe
3
O
4
/SiO
2
/CdS nanocomposites (S2)
7

3 4 2
Figure 4. EDX spectrum of the Fe O /SiO /CdS nanocomposites (S2)
The ultraviolet-visible (UV-Vis) and diffuse reflectance spectra (DRS) were used to determine the optical properties
of the samples (Figure 5). The UV–Vis spectra showed extended absorption within the visible light range compared
3 4 2
with bare CdS. The enhanced absorption capability of visible light of Fe O /SiO /CdS nanocomposites suggests that
it might have the higher photocatalytic activity for target reactions under visible light irradiation. A plot obtained via
the transformation based on Kubelka-Munk function versus the energy of light is shown in (Figure 5b and 5c). As the
amount of CdS precursors increased, the amount of band gap decreased as a result of the increase in particles size.
2
The BET specific surface area of the samples was calculated for N isotherm and was found to be about 103.25, 23.65,
2
1
1.26, and 10.92m /g for S0, S1, S2, and S4. These results showed that growing CdS particles on the surface of
3 4 2
Fe O /SiO nanoparticles led to a decreased BET surface area.
3 4 2
Figure 5. (a) UV-Vis diffuse reflectance spectra (DRS) of the bare CdS and Fe O /SiO /CdS nanocomposites (S1, S2,
and S4), (b, c) the plot of transformed Kubelka-Munk function versus the energy of light
8

Magnetic measurements were investigated using VSM at room temperature in the applied magnetic field sweeping
from -10 to 10 kOe (Figure 6). The saturation magnetization of these magnetic nanoparticles was between 20-18
emu/g. The decrease in Ms is attributed to the increased mass of CdS nanoparticles. Good magnetic properties imply
3 4 2
strong magnetic responsivity of Fe O /SiO /CdS, which enable them to be separated easily.
Figure 6. Room temperature magnetization curve of Fe
and S4)
3 4 2 3 4 2
O /SiO (S0) and Fe O /SiO /CdS nanocomposites (S1, S2,
Quantitative weight fraction of CdS in each sample was calculated based on atomic absorption spectrometer. The
results show that the weight fraction of CdS in the sample increases by increasing the amount of CdS precursors. More
specifically, it is 40%, 54%, and 60% in samples S1, S2, and S4, respectively.
In a series of further experiments, it was found that as the amount of CdS precursors increased, the CdS formation
was not only led on the surface of MNPs and the CdS particles tended to rapidly aggregate in a random manner.
Additionally, in this condition, the magnetic properties of nanocomposites decreased and good separation was not
achieved by external magnet.
3 4 2
The photocatalytic activity of Fe O /SiO /CdS nanocomposite (S2) was examined in the photocatalytic reduction of
nitrobenzene under the blue LED irradiation. According to the DRS spectra, the maximum absorption of the
synthesized samples was near the wavelengths distribution of the blue LED [55]. Therefore, the blue LED was selected
as a light source to examine the photocatalytic activity of the photocatalyst. In addition, using LED lamps as a light
source is associated with several advantages such as high photon efficiency, low voltage electrical power source,
power stability, emission in broader spectral wavelength, and no need for cooling during long time operation for
complete photocatalytic reactions [56-58].
9

In order to determine optimal experimental condition, the reduction of nitrobenzene was subjected to a series of
experimental conditions: first, the impact of various solvents such as EtOH and i-PrOH were examined.
Table 1. Optimization of the photocatalytic reduction condition of nitro benzene with Fe
3
O
4
/SiO
2
/CdS nanocomposites
Selectivity (%)
(S2) under blue LED (3 W) irradiation and argon atmosphere, irradiation time: 20 h.
a
a
Entry
Nitrobenzene (M)
Solvent
Fe
3
O
4
/SiO
2
/CdS (mg)
Aniline (%)
Conversion (%)
1
2
3
4
5
0.01
0.01
0.01
0.01
0.001
0.01
0.01
0.01
EtOH
20
20
40
10
20
7
98
48
100
30
100
0
7
i-PrOH
i-PrOH
i-PrOH
i-PrOH
i-PrOH
i-PrOH
i-PrOH
43
36
25
12
0
90
36
25
12
0
b
6
100
0
7
0
0
0
c
8
20
0
0
0
a
b
c
Determined by gas chromatography.
In the dark.
Under air atmosphere.
It was found that i-PrOH was better as a reaction solvent for this photocatalytic reaction (Table 1, entries 1 and 2). In
the presence of EtOH, the low selectivity of amine was observed. Notably, increasing the amount of photocatalyst
from 10 to 20 mg resulted in higher yields, but increasing the amount of photocatalyst to 40 mg did not produce
significant higher yields than the 20 mg of the photocatalyst (Table 1, entries 2-4). It was also noted that the reduction
of nitrobenzene was not observed neither without Fe
3 4 2
O /SiO /CdS under LED irradiation nor using the
Fe /SiO /CdS without LED irradiation (Table 1, entries 6 and 7). In addition, photocatalytic activity was observed
3
O
4
2
only in argon atmosphere (Table 1, entry 8). Other optimum results are illustrated in Table 1. With optimal reaction
conditions for the photocatalytic reduction of nitrobenzene under blue LED irradiation, the scope of this new
photocalytic reduction protocol was then investigated for other aromatic nitro compounds. As shown in Table 2,
various types of aromatic nitro compound, including those with both electron-withdrawing and electron-donating
groups, were converted to the corresponding amines in good yields under the optimal reaction conditions. These results
show that electronic effects have significant effect on the products yields. Electron-deficient nitrobenzene derivatives
have higher yields in this reaction condition due to their higher reduction potential.
1
0

3 4 2
Table 2. Photocatalytic reduction of nitrobenzene derivatives to corresponding amines via Fe O /SiO
/CdS nanocomposite (S2).a
b, c
b, c
c
Entry
1
Starting material
Amine
Yield (%)
95(94)
Conversion (%)
100(100)
Selectivity
95(94)
O
O
O2N
H2N
NO2
NH2
2
3
4
98(96)
94(93)
40(18)
100(98)
100(100)
50(25)
98(98)
94(93)
80(72)
NC
NC
NO2
NH2
O2N
O2N
NO2
NO2
O
NO2
NH2
O
NO2
H3C
NH2
5
6
H3C
100(81)
43(2)
100(82)
52(3)
100(98)
83(66)
NO2
NH2
NO2
NH2
7
30(4)
79(5)
40(80)
CH3
NO2
CH3
NH2
8
9
80(15)
60(3)
60(2)
100(17)
100(7)
90(64)
80(88)
60(42)
67(31)
Cl
Cl
NO2
NH2
H3C
H3C
NO2
NH2
1
0
NO2
NH2
1
1
1
1
2
3
63(3)
55(6)
19
100(5)
65(8)
21
63(60)
85(75)
90
OMe
OMe
NO2
NH2
ClH2C
ClH2C
NH2
NO2
d
a
b
c
d
−2
Photocatalyst: 20 mg; nitro compound alcoholic solution (1 × 10 M) 5 mL; blue LED irradiation (3 W) 80 Lumen; irradiation time: 20 h.
Determined by gas chromatography.
Numbers in parentheses represent results in the presence of 20 mg of the bare CdS.
In the presence of commercial CdS (Aldrich).
1
1

3 4 2
Fe O /SiO /CdS nanocomposite exhibited a much higher activity than bare CdS (Table 2). The photoirradiation of
CdS photocatalysts leads to optical excitation across the band gap resulting in charge separation within the particles,
that is, the excitation of electrons into the conduction band and the accompanying hole generation in the valence band
3 4 2
under visible light irradiation. The high efficiency of Fe O /SiO /CdS nanocomposites as a photocatalyst is attributed
to a large driving force for electron transfer from CdS to nitro compounds. The reduction potential of aromatic nitro
compounds has been reported between −0.59 and −0.25 V vs NHE [59] and suitable levels of CdS conduction band
(
CB: −0.75 V vs NHE) [60] clearly recognized the thermodynamic aspect of electrons realizing from CdS conduction
bond to the aromatic nitro compounds. In addition, the silica core as a photochemically inactive support exerts a
positive influence on the reaction rate through including selective substrate adsorption, providing stability of nano
sized CdS, and effective prevention of CdS agglomeration [61, 62]. As a result, the adsorbed nitro compounds on
silica surface can be effectively reduced to their corresponding amines by accepting photocatalytic generated electrons
(
Figure 7). The photoactivity of Fe
3 4 2
O /SiO /CdS nanocomposites in the photoreduction of nitrobenzene was also
compared with that of commercial CdS (Aldrich) as a typically available photocatalyst. Commercial CdS tended to
agglomerate to the size of more than 100 nm [52]. It was observed that the synthesized Fe
nanocomposites are more efficient than commercial CdS (Aldrich) (Table 2, entries 13).
3 4 2
O /SiO /CdS
3 4 2
Figure 7. Photocatalytic reduction of nitro compounds in the presence of Fe O /SiO /CdS nanocomposites
3 4 2
To study the reusability and stability of the Fe O /SiO /CdS nanocomposites, the photocatalytic reduction of 3-
nitroacetophenone was repeated for five times with the same photocatalyst (Figure 8). After each run, the photocatalyst
was separated by external magnet and washed with i-PrOH, then used again in the photocatalytic reduction of
3 4 2
nitrocompound. The little decrease observed after each run can be attributed to the loss of Fe O /SiO /CdS
1
2

nanocomposites during washing and separating steps. In addition, some CdS particles were detached from the
core/shell surface during the recycling of the photocatalyst. However, the amount of Cd2+ is detected
3 4 2
Fe O /SiO
before and after each reaction (runs 1–5) by atomic absorption spectroscopy (AAS) (which was 0.9 and 2.1, 2.3, 3.7,
.1, and 4.2 ppm respectively), demonstrating the negligible detaching of CdS from the surface of the photocatalyst.
This indicates that the Fe /SiO /CdS catalysts are fairly stable and possess the potential for practical application.
4
3
O
4
2
Figure 8. Representation of 3-amino acetophenone yields at different reuses of the photocatalyst
4
. Conclusions
In conclusion, magnetic Fe
The photocatalytic performance of the as-prepared photocatalysts was examined by the reduction of a wide range of
aromatic nitro compounds under visible LED irradiation. The Fe /SiO /CdS nanocomposites exhibited enhanced
3 4 2
O /SiO /CdS nanocomposites were synthesized through a facile and convenient method.
3
O
4
2
photoactivity as compared with bare CdS and commercial CdS (Aldrich). This system couples the advantages of LED
irradiation with low electrical power as a visible light source and easy separation and reusability of the photocatalyst,
which makes it as a promising photocatalyst for other organic transformations.
Acknowledgments
The authors gratefully acknowledge the support provided by the Institute for Advanced Studies in Basic Sciences
(
IASBS).
1
3

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