In situ synthesis of C3N4/Bi2S3 composites with enhanced photocatalytic degradation performance under visible light irradiation

Article abstract of DOI:10.1002/jccs.201800002

Carbon nitride/bismuth sulfide (C₃N₄/Bi₂S₃) nanocomposites were prepared by a facile one-step in situ calcination method using ammonium thiocyanate and bismuth chloride as reagents. The crystal structure, composition, and morphology of the nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photocatalytic degradation of rhodamine B (RhB) was carried out to evaluate the photocatalytic activity of the nanocomposites under visible light irradiation. The as-prepared C₃N₄/Bi₂S₃ nanocomposites displayed enhanced visible light absorption. These photocatalysts exhibited superior photodegradation performance under visible light irradiation compared to pure C₃N₄. Meanwhile, the C₃N₄/Bi₂S₃ nanocomposites exhibited remarkably stable photocatalytic efficiency after five cycles of photodegradation of RhB. The C₃N₄/Bi₂S₃ heterostructure improved the separation and transfer efficiency of the photogenerated electron–hole pairs. It played an important role for the enhanced photocatalytic performance of the nanocomposite photocatalysts.

Full text of DOI:10.1002/jccs.201800002

Received: 2 January 2018
Revised: 26 March 2018
Accepted: 12 April 2018
DOI: 10.1002/jccs.201800002
A R T I C L E
In situ synthesis of C3N4/Bi2S3 composites with enhanced
photocatalytic degradation performance under visible light
irradiation
Jian Yin1,2 | Zhenyu Wu1 | Min Fang1,3 | Ying Xu1 | Weiju Zhu1,3 | Cun Li1,2
1School of Chemistry and Chemical Engineering,
Carbon nitride/bismuth sulfide (C3N4/Bi2S3) nanocomposites were prepared by a
Anhui University, Hefei, China
2AnHui Province Key Laboratory of Chemistry for
Inorganic/Organic Hybrid Functionalized
Materials, Anhui University, Hefei, China
3Anhui Province Key Laboratory of Environment-
friendly Polymer Materials, Anhui University,
Hefei, China
facile one-step in situ calcination method using ammonium thiocyanate and bis-
muth chloride as reagents. The crystal structure, composition, and morphology of
the nanocomposites were characterized by X-ray diffraction (XRD), Fourier trans-
form infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and
transmission electron microscopy (TEM). The photocatalytic degradation of rhoda-
mine B (RhB) was carried out to evaluate the photocatalytic activity of the
nanocomposites under visible light irradiation. The as-prepared C3N4/Bi2S3 nano-
composites displayed enhanced visible light absorption. These photocatalysts
exhibited superior photodegradation performance under visible light irradiation
compared to pure C3N4. Meanwhile, the C3N4/Bi2S3 nanocomposites exhibited
remarkably stable photocatalytic efficiency after five cycles of photodegradation of
RhB. The C3N4/Bi2S3 heterostructure improved the separation and transfer effi-
ciency of the photogenerated electron–hole pairs. It played an important role for
the enhanced photocatalytic performance of the nanocomposite photocatalysts.
Correspondence
Cun Li, School of Chemistry and Chemical
Engineering, Anhui University, Hefei 230601,
China.
Email: cun_li@126.com
Funding information
Graduate Academic Innovation Research Project
Fund of Anhui University, Grant/Award Number:
yqh100085; Natural Science Foundation of
Education Department of Anhui Province,
Grant/Award Number: KJ2017A008; Dr. Research
Project Fund of Anhui University, Grant/Award
Number: 33190213; National Natural Science
Foundation of China, Grant/Award Numbers:
51472001, 21404001
KEYWORDS
bismuth sulfide, carbon nitride, photocatalyst, photodegradation
efficiency during the photocatalytic reaction.[6–8] In addition,
g-C3N4 can absorb and utilize only ultraviolet and visible
1
| INTRODUCTION
Photocatalysis using nanomaterials holds extensive potential
applications in the energy and environmental fields. Wang
et al.[1] first reported that graphitic carbon nitride (g-C3N4)
could be used as a photocatalyst to produce hydrogen from
water using visible light. Since then, g-C3N4 with a
π-conjugated inorganic polymer semiconductor has drawn
much attention, especially as a promising semiconductor
photocatalyst for use in environmental and energy
photocatalysis.[2–5] However, owing to the high exciton
binding energy and low mobility of carriers, the photogener-
ated electron–hole pair separation efficiency in C3N4 semi-
conductor is low, which leads to high recombination rate of
the photo-induced electrons and holes and low quantum
light in a narrow wavelength range of less than 460 nm
because of its bandgap of ~2.7 eV.[9] These main drawbacks
limit its practical application as an efficient photocatalyst in
the visible light region.
It is well known that the formation of a heterojunction
structure with two different coupled semiconductors is an
efficient method to accelerate the separation of photogener-
ated electron–hole pairs. It has been reported that the cou-
pling of C3N4 with TiO2 is a simple technique to improve its
photocatalytic performance.[10] Sun et al. reported that the
C3N4/ZnO heterojunction showed higher photodegradation
activity and cyclic stability than those of the individual com-
ponents.[11] Therefore, in order to extend the range of visible
© 2018 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J Chin Chem Soc. 2018;1–9.
http://www.jccs.wiley-vch.de
1

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light absorption and overcome the disadvantages of g-
C3N4,[6] the novel photocatalyst composites with narrow-
bandgap semiconductors were considered.
Bismuth sulfide (Bi2S3) is a promising inorganic semi-
conductor material because of its good photocatalytic activ-
ity, nontoxicity, chemical stability, and visible light
response.[12,13] It has been investigated and exploited largely
for optoelectronic applications.[14,15] C3N4/Bi2S3 composites
are advanced materials for photocatalytic applications.
Recently, a nanocomposite of C3N4 coupled to the narrow-
bandgap semiconductor Bi2S3 was synthesized by a two-step
method.[16] The photocatalytic efficiency of this nanocompo-
site was much higher than that of the individual components.
Zhou et al.[17] obtained C3N4/Bi2S3 composites by using the
microwave-assisted method and found that its visible light
photocatalytic degradation activity with methyl orange
increased significantly. The well-matched bandgap of the
C3N4/Bi2S3 heterojunction could be constructed to improve
the separation and transfer efficiency of photo-induced car-
riers and visible light response. All these results demonstrate
that C3N4/Bi2S3 composites are efficient photocatalysts for
the photocatalytic degradation of environmental pollutants.
It has been reported that ammonium thiocyanate could
be used as a precursor to synthesize C3N4 by pyrolysis
polymerization,[18] but sulfur is lost during the synthesis pro-
cess. It has been found that in situ growth could not only
greatly increase the specific surface area but also reduce the
size of the nanoparticles.[19] Here we report a simple one-
step in situ calcination method by using ammonium thiocya-
nate and bismuth chloride mixture to prepare C3N4/Bi2S3
nanocomposites. Bi2S3 nanoparticles are produced from the
reaction of BiCl3 and sulfur, and the sulfur is produced from
the pyrolysis polymerization of NH4SCN; this is one of the
novel strategies to utilize the sulfur source of NH4SCN. The
photocatalytic activity of the nanocomposites on the envi-
ronmental contaminant rhodamine B (RhB) was carried out
and investigated in detail. We found that C3N4/Bi2S3 nano-
composites exhibited superior photocatalytic performance
and higher stability toward RhB degradation under visible
light irradiation compared to those with the C3N4 component
alone. The obtained results show that C3N4-based nanocom-
posite photocatalysts with high efficiency and stability can
be developed for practical applications in the environmental
and energy fields.
FIGURE 1 XRD patterns of different C3N4/Bi2S3(X) samples
of hexagonal g-C3N4 (JPCDS No.87-1526).[17] It can also be
seen that with increasing amounts of Bi2S3 in composites,
the diffraction peaks of Bi2S3 become obvious and coexist
with those of g-C3N4. The new high-intensity diffraction
peaks at 24.9o and 28.7ꢀ correspond to the (130) and (211)
planes of the orthorhombic phase Bi2S3 (JCPDS
No. 17-320). This indicates that the Bi2S3 nanocrystals are
embedded in the bulk C3N4 from this one-step in situ syn-
thesis route. These results also indicate that the in situ pro-
duced Bi2S3 nanocrystals might have deposited on the
surface of graphite-like layer structure of g-C3N4.
Fourier transform infrared (FT-IR) spectra of the as-
synthesized C3N4/Bi2S3 nanocomposites are displayed in
Figure 2. It is worth noting that bulk C3N4 and C3N4/Bi2S3
samples show similar FT-IR absorption peaks. The broad
absorption band at 3100–3300 cm−1 can be assigned to the
stretching modes of the secondary and primary amines as well
as the stretching vibration of O–H of the absorbed water mol-
ecule and their intermolecular hydrogen-bonding interac-
tions.[6,21] All the samples are characterized by a series of
bands in the 1200–1600 cm−1 region and a strong peak at
about 800 cm−1. The bands at 1200–1600 cm−1 are character-
istic of the aromatic carbon nitride heterocycles.[22] The
band around 806 cm−1 corresponds to the stretching vibra-
tions of the triazine ring.[23] These IR bands are typical molec-
ular vibration modes of the triazine and heptazine rings in g-
C3N4. The results indicate that the layer structure of g-C3N4 is
not changed upon the formation of Bi2S3 nanocrystals.
To investigate the morphology of the as-prepared C3N4/
Bi2S3 samples, scanning electron microscopy (SEM) images
of pure C3N4 and C3N4/Bi2S3(0.5%) samples were taken,
which are shown in Figure 3. It can be seen from Figure 3a
that pure C3N4 is composed of irregular lamellar particles of
micrometer size. Figure 3b shows the morphology of
C3N4/Bi2S3(0.5%) composites. The composites also display
the major characteristic layer morphology of C3N4. Mean-
while, the surfaces of the composites are relatively smooth,
2
| RESULTS AND DISCUSSION
2.1 | Structure and morphology study
Figure 1 shows the X-ray diffraction (XRD) ꢀpatterns of the
C3N4/Bi2S3 nanocomposites prepared at 550 C with differ-
ent Bi2S3 contents. For all samples, the diffraction peaks
appeared at 12.9ꢀ and 27.6ꢀ, which can be assigned to the g-
C3N4 layers,[20] corresponding to the (100) and (002) planes

YIN ET AL.
3
FIGURE 2 FT-IR spectra of different C3N4/Bi2S3(X) samples
indicating that the nanoparticles of Bi2S3 are dispersed uni-
formly in the C3N4 bulk. The corresponding energy disper-
sive X-ray spectrum (EDS) result of C3N4/Bi2S3(0.5%) is
displayed in Figure 3c. It can be seen that C3N4/Bi2S3(0.5%)
consists of C, N, Bi, and S. This indicates that the in situ
growth of a small number of Bi2S3 nanoparticles does not
influence the structure of graphite-like C3N4.
Transmission electron microscopy (TEM) and high-
resolution (HR)TEM were used to characterize the morphol-
ogy and crystalline structure of the Bi2S3 nanoparticles in the
nanocomposites. Figure 4a and b show typical TEM images
of pure C3N4 and C3N4/Bi2S3(0.5%), respectively. The Bi2S3
nanoparticles with size 5–7 nm are embedded in the C3N4
matrix, as seen from the TEM image of C3N4/Bi2S3(0.5%)
(Figure 4b). Figure 4c presents the HRTEM photograph of
the nanocomposite. Some Bi2S3 nanocrystallites of several
nanometers show clear fringe spacing with an interval of
0.36 nm, which could be indexed to the (130) lattice plane
of Bi2S3.[24,25] The lattice fringes at the interface of the com-
posites are discontinuous, and the interfacial edge of Bi2S3
nanoparticles displays the obscure flake folds of C3N4, indi-
cating that special heterostructures have been formed.
X-ray photoelectron spectroscopy (XPS) gives the struc-
tural environment of the elements of C3N4/Bi2S3 sample.
Figure 5 shows the XPS spectra of C3N4/Bi2S3(0.5%). There
are some peaks due to C, N, S, and Bi in the survey spec-
trum (Figure 5a), which is consistent with the elements of
the C3N4/Bi2S3 composite. The higher resolution spectra of
the C 1s, N 1s, Bi 4f, and S 2p regions were also obtained.
The C 1s spectrum contains two peaks at 288 and 284.6 eV.
The peak of 288 eV is ascribed to the sp2 hybrid carbon in
the aromatic ring. The C 1s peak at 284.6 eV is usually
assigned into graphitized carbon or sp2 C–N.[26] The N 1s
peak can be deconvoluted into three peaks. The main peak at
398.2 eV is attributed to the sp2 hybrid N on the triazine
ring, while the peak at 400 eV corresponds to the bridging N
atoms connected to three triazine rings N–(C)3.[27] The high-
FIGURE 3 SEM images of (a) pure C3N4 and (b) C3N4/Bi2S3(0.5%)
(c) EDS results
.
energy peak at 404.1 eV comes from the charging effect or
positive charge localization in the heterocycles.[28] In addi-
tion, the characteristic Bi 4f peaks were present at 158.4 and

4
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FIGURE 5 XPS survey spectrum of C3N4/Bi2S3(0.5%) (a) and the
corresponding high-resolution XPS spectra of C 1s (b), N 1s (c), Bi 4f (d),
and S 2p (e)
2.2 | Optical characterization
The UV–vis–NIR absorption spectra of the as-prepared
C3N4/Bi2S3 nanocomposites are shown in Figure 6. It is
obvious that all the curves have a stronger absorption edge
at about 460 nm, which corresponds to the bandgap of
C3N4 of ~2.7 eV. All the C3N4/Bi2S3 nanocomposite sam-
ples show a distinct absorption band at ~950 nm, which
corresponds to the bandgap of Bi2S3, which is
~1.3 eV.[31,32] With increasing the Bi2S3 content, the
FIGURE 4 TEM images of (a) pure C3N4 and (b) C3N4/Bi2S3(0.5%)
.
(c) HRTEM images of C3N4/Bi2S3(0.5%)
163.6 eV. These peaks are lower in energy compared to the
standard XPS binding energy (158.8 and 164.3 eV) for Bi3+
4f, which indicates an increase in the electron density of
Bi2S3.[29] This may have originated from the electron trans-
fer between C3N4 and Bi2S3 in the composites. Meanwhile,
the XPS spectrum also confirms the existence of sulfur spe-
cies from the appearance of an S 2p peak at 163.7 eV, which
is consistent with the literature.[30] The results show that the
existence of Bi2S3 nanoparticles does not change the basic
chemical structure of C3N4. The formation of the heterojunc-
tion composites may favor the electron transfer between
C3N4 and Bi2S3.
FIGURE 6 UV–vis–NIR spectra of the C3N4 and different C3N4/Bi2S3(X)
samples

YIN ET AL.
5
TABLE 1 Surface area, total pore volume, and average pore diameter of
the as-prepared samples
Total pore
Average pore
diameter (nm)
Samples
X = 0
Surface area (m2/g)
18.003
volume (cm3/g)
0.772
0.19
46.171
40.131
42.147
47.366
43.692
X = 0.1%
X = 0.3%
X = 0.5%
X = 1%
31.657
40.752
0.225
0.48
44.029
27.325
0.323
spectral region of sunlight. This is attributed to the narrow
bandgap of Bi2S3 nanoparticles and the heterojunction
between C3N4 and Bi2S3.
The efficiency of recombination of the photogenerated
electron–hole pairs in the nanocomposites was investigated
from the photoluminescence (PL). It can be seen in Figure 7
that all the samples exhibit a broad emission peak centered
at ~480 nm, which can be attributed to the electron–hole
recombination PL phenomenon with the photon energy
approximately close to the bandgap energy (2.7 eV) of
C3N4.[33] The PL intensity of C3N4 significantly decreases
when it is blended with the Bi2S3, and it reduces with the
increase in Bi2S3 content. But X = 1% was abnormal, indi-
cating that Bi2S3 plays a leading role in the composites as
the Bi2S3 content increases.[16] The PL intensity of C3N4 in
C3N4/Bi2S3(0.5%) sample is the lowest. The fluorescence
quenching effect indicates that the C3N4 coupled with Bi2S3
will inhibit the recombination of photogenerated electron–
hole pairs. The main advantage of the heterojunction struc-
ture is to promote the separation of the electrons and holes
and the mobility of free carriers.[34–36] This will lead to high
separation efficiency and low recombination rate of the
photogenerated charge carriers, which is of great benefit to
photocatalytic reactions.
FIGURE 7 PL spectra of C3N4 and C3N4/Bi2S3 samples
absorption of C3N4/Bi2S3 in the visible and near-infrared
(NIR) regions increases, which is attributed to the good
optical absorption ability of Bi2S3. The increase in light
absorption can improve the utilization of the visible
FIGURE 8 (a) Nitrogen adsorption–desorption isotherms and (b) the
corresponding pore size distribution curves of the as-prepared samples
FIGURE 9 Photocatalytic degradation of RhB over different C3N4/Bi2S3(X)
samples obtained at 550 ꢀC under visible light irradiation

6
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2.3 | Specific surface area analysis
temperature. It has been reported that defects would increase
in bulk C3N4 prepared at higher temperature, which can pro-
mote electron localization.[37] The RhB degradation process
was fitted using quasi-first-order kinetics, and the apparent
rate constants are shown in Figure 10c. Compared to that of
The nitrogen adsorption–desorption isotherms of the as-
prepared samples are presented in Figure 8a. Type-III
isotherms with a sharp capillary condensation step at high
relative pressures with H3 hysteresis loops are observed. The
H3 hysteresis loops might be ascribed to the slits due to the
aggregation of plate-like particles. Figure 8b shows the cor-
responding pore size distribution curves centered at ~45 nm.
Table 1 gives the surface area, total pore volume, and aver-
age pore diameter in detail. It is found that C3N4/Bi2S3(0.5%)
exhibits the highest surface area of 44.029 m2/g, with a total
pore volume of 0.48 cm3/g and an average pore diameter of
47.366 nm. The larger surface area favors heterogeneous
photocatalysis reaction. Therefore, this sample is expected to
exhibit the highest photocatalytic activity.
2.4 | Photocatalytic activity
The photocatalytic activity of the C3N4/Bi2S3 nanocompo-
sites with different Bi2S3 contents was evaluated by the
photodegradation of the organic dye RhB under visible light
irradiation. The results are displayed in Figure 9. It can be
seen that all nanocomposites demonstrate enhanced photode-
gradation performance compared to pure C3N4 and pure
Bi2S3. The photocatalytic degradation activity of C3N4/
Bi2S3 was significantly improved with increase in the Bi2S3
content. The C3N4/Bi2S3(0.5%) sample showed the best
photodegradation activity, while the photocatalytic activity
of C3N4/Bi2S3(1%) was slightly reduced. In our experiments,
the Bi2S3 nanoparticles dispersed uniformly in the C3N4
bulk instead of depositing on the surface of C3N4 as reported
earlier. Hence, heterojunction structures exist throughout the
composites, not only on the surface of the catalyst. The
photocatalyst with the higher Bi2S3 content did not possess
higher activity. It might be due to the formation of some
recombination centers of photo-induced electron–hole pairs
in the bulk of the catalyst. This is consistent with the results
of the PL investigation (Figure 7). On the other hand, exces-
sive Bi2S3 in the composites increased the agglomeration of
the nanoparticles.
The effects of the preparation conditions on photocataly-
tic activity of C3N4/Bi2S3 nanocomposites were investigated.
The corresponding photocatalytic activity of pure C3N4 and
C3N4/Bi2S3(0.5%) samples synthesized at different tempera-
tures was measured, and the results are shown in Figure 10a
and b. It can be seen that the photodegradation of RhB by
pure C3N4 and C3N4/Bi2S3 was influenced obviously by the
calcination temperature. The results reveal that the photoca-
talytic activity of pure C3N4 and C3N4/Bi2S3 samples syn-
ꢀ
thesized at 500 and 450 C was poꢀor. However, when the
calcining temperature exceeded 500 C, the activity of these
two kinds of catalysts improved significantly. Especially, the
photocatalytic activity of C3N4/Bi2S3 samples was much
higher than that of pure C3N4 prepared at the same
FIGURE 10 Photocatalytic activity of (a) C3N4 and (b) C3N4/Bi2S3(0.5%-T)
prepared at different temperatures. (c) Photocatalytic degradation rate
constant of RhB for the first-order kinetics (the “ꢀC” had been modified
in (c))

YIN ET AL.
7
FIGURE 11 Stability of C3N4/Bi2S3(0.5%) for RhB photodegradation under
visible light irradiation
pure C3N4, the photocatalytic reaction of C3N4/Bi2S3 nano-
composites was accꢀelerated significantly. For the samples
synthesized at 550 C, the apparent rate constant of RhB
photodegradation of C3N4/Bi2S3 was 1.5 times that of pure
C3N4. C3N4/Bi2S3(0.5%-600) sample shows the largest reaction
rate, which is 2 times that of pure C3N4. This apparent
kinetic constant is higher than that of the best composite
sample (Bi2S3/g-C3N4–4) synthesized by two steps.[16]
FIGURE 12 Schematic of photogenerated charge transfer in the C3N4/
Bi2S3 system under visible light irradiation
decomposition products.[10,16,38] In the process, the accelera-
tion in charge separation reduces the probability of charge
recombination. The photo-erosion of Bi2S3 can be prevented
by the encapsulated C3N4 sheets. As a result, the photocata-
lytic activity and stability of the composites material are
increased.
2.5 | Photocatalytic stability
The impacts of active species such as O2•−, OH•, h+,
and e− in the photocatalytic degradation process are shown
in Figure 13. When isopropanol (10−3 M, 5 mL) was
selected as the scavenger for the OH• radicals, the degrada-
tion rate only slightly decreased, indicating that OH• did not
play an important part during the photocatalytic process.
This may be because the generation of OH• radicals was
very fast, so isopropanol did not have enough time to take
part in the reaction. Thus the influence of isopropanol was
To determine the photostability of the nanocomposite cata-
lysts, the photodegradation of RhB by C3N4/Bi2S3(0.5%) was
repeated for five cycles under the same conditions. After five
recycling experiments, the catalyst still maintained its high
photodegradation activity and no apparent reduction in
photocatalytic performance was detected (Figure 11). The
results show that the nanocomposite photocatalyst was stable
under the experimental conditions. This is important for the
practical application of the photocatalyst.
2.6 | Photocatalytic mechanism
A plausible mechanism of the separation and transport of the
photogenerated charges of C3N4/Bi2S3 during the photode-
gradation is shown in Figure 12. The conduction band
(CB) and valence band (VB) potentials of Bi2S3 are esti-
mated to be −0.2 and 1.1 eV, while those of C3N4 are −1.3
and 1.4 eV.[16] When a C3N4/Bi2S3 sample is irradiated by
visible light (λ > 400 nm), C3N4 and Bi2S3 can be excited
to produce photogenerated electrons (e−) and holes (h+).
Because of the connected heterojunction interface and the
well-matched VB structure, some holes in the VB of C3N4
can easily transfer to the VB of Bi2S3 spontaneously. This
will promote the separation of electrons and holes. The
active free-radical species of superoxide radical (O2•−) can
react with H2O to generate active hydroxyl radical (OH•),
and abundant OH• can oxidize organic substrates to
FIGURE 13 Effects of O2•−, OH•, h+, and e− during the degradation of
RhB with the addition of different scavengers

8
YIN ET AL.
not obvious. However, after adding N2 and EDTA-2Na
(10−3 M, 5 mL), respectively, the photocatalytic activity was
First, 15 g NH4SCN was mixed with different amounts of
BiCl3 in 20 mL ethanol solution. Then, ethanol was
greatly suppressed, indicating that the O2 and/or h+ were
•−
ꢀ
removed by evaporation at 80 C. After thorough drying in
ꢀ
the main oxidative species in the degradation of RhB. Oxy-
gen was reduced with the purging of nitrogen, which limited
the generation of the superoxide radical. This led to more
recombination of electron and holes, as seen from Figure 12.
EDTA-2Na can act as an effective electron donor to trap
holes produced from the VB of nanoparticles due to irradia-
tion by visible light,[39] thus inhibiting the oxidation capacity
of holes in the nanocomposites (as shown in Figure 12). In
addition, it is found that the degradation rate is drastically
promoted by the addition of the electron capture agent silver
nitrate (10−3 M, 5 mL), which further shows that electrons
play an important role in the organic contaminant degrada-
tion process. It could be considered that the Ag+ was
reduced by the electrons. Then, the advantage of Ag to act
as an electron storage increases, minimizing the electron–
hole pair recombination rate while enhancing the perfor-
mance of photocatalysis.[40]
an oven, the solid mixtures were calcined at 550 C for 2 hr
ꢀ
at a ramp rate of 5 C/min in N2 atmosphere to acquire yel-
low samples. The obtained samples were denoted as C3N4/
Bi2S3(X-T), where X (X = 0, 0.1, 0.3, 0.5, 1%) refers to the
initial mass ratio of BiCl3/NH4SCN, and T refers to the cal-
cination temperature. The productivity of C3N4 acquired
using NH4SCN as a precursor was about 6%, and according
to the inductively coupled plasma (ICP) test results, the real
mass ratio of Bi2S3 to C3N4 in the composites was about 5%
for C3N4/Bi2S3(0.5%-550). The letter “T” of the samples pre-
pared at 550 ꢀC was omitted unless otherwise noted.
4.2 | Characterization
XRD measurements were carried out on a DX-2700 diffrac-
tiometer using Cu Kα radiation (λ = 1.5406 Å) at 40 kV
and with a 30 mA flux, at the scanning rate of 4ꢀmin−1. FT-
IR spectra were recorded using a Vertex80 FT-IR spectrom-
eter in KBr pellets. Field-emission (FE)SEM measurements
were performed on a Hitachi S-4800 scanning electron
microscope. HRTEM images were obtained on a JEM-2100
high-resolution TEM (Japan Electron Co.) at an accelerating
voltage at 200 kV. The UV–visible–near infrared (UV–vis–
NIR) adsorption spectra were recorded on a Hitachi U-4100
spectrometer in the range 240–1800 nm. The room-
temperature PL spectra were recorded on a fluorescence
spectrophotometer (Hitachi F-4500). XPS data were
obtained on a ESCALAB 250Xi instrument. ICP tests were
carried out on an iCAP 7400 Duo device.
3
| CONCLUSIONS
C3N4/Bi2S3 nanocomposite catalysts with different Bi2S3
contents were successfully prepared by a one-step in situ
technique using NH4SCN and BiCl3 as precursors. Small
Bi2S3 nanocrystals were uniformly distributed in the bulk of
the C3N4 matrix. A well-constructed heterojunction between
C3N4 and Bi2S3 of the nanocomposites resulted in enhanced
visible light absorption and acceleration of the separation
rate of the photoexcited charger carriers. Under visible light
irradiation, the photocatalytic degradation of RhB by the
nanocomposites was more efficient compared to that with
the pure C3N4 photocatalyst. The content of Bi2S3 and the
preparation temperature had significant influence on the
photocatalytic activity of the C3N4/Bi2S3 catalyst. C3N4/
Bi2S3(0.5%-550) demonstrated good photocatalytic activity and
reusability under the experimental conditions. The experi-
mental results prove that one-step in situ synthesis of carbon
nitride-based composites modified with small amounts
narrow-bandgap semiconductors of metal sulfides with high
photocatalytic efficiency and good stability is feasible.
4.3 | Photocatalytic test
The photodegradation activity of C3N4/Bi2S3 nanocomposite
photocatalysts were evaluated using RhB solution
(1.0 × 10−5 mol/L) as a simulation of wastewater. The light
source for the photocatalytic reaction was a 300 W Xe lamp
combined with a cutoff filter to remove light wavelengths
below 400 nm. Fifty milligrams of the photocatalyst was
added to 100 mL of the model pollutant solution. After stir-
ring in the dark for 30 min to ensure adsorption–desorption
equilibrium, the solution was exposed to visible light radia-
tion. The RhB concentration was analyzed by the UV–vis
spectrophotometer at certain irradiation time intervals.
4
| EXPERIMENTAL
All the reagents were purchased from Sinopharm Chemical
Reagent Co, Ltd. (Shanghai, China) and used as received
without further purification.
ACKNOWLEDGMENTS
This work was financially supported by the National Natural
Science Foundation of China (no. 21404001, 51472001), the
Dr. Research Project Fund of Anhui University
(no. 33190213), the Natural Science Foundation of Educa-
tion Department of Anhui Province (No. KJ2017A008), and
4.1 | Synthesis of C3N4/Bi2S3 nanocomposites
C3N4/Bi2S3 samples were synthesized by a one-step in situ
calcination method from a mixture of NH4SCN and BiCl3.

YIN ET AL.
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How to cite this article: Yin J, Wu Z, Fang M,
Xu Y, Zhu W, Li C. In situ synthesis of C3N4/Bi2S3
composites with enhanced photocatalytic degradation
performance under visible light irradiation. J Chin
Chem Soc. 2018;1–9. https://doi.org/10.1002/jccs.
201800002