In-situ precipitation synthesis of novel BiOCl/Ag2CO3 hybrids with highly efficient visible-light-driven photocatalytic activity

Article abstract of DOI:10.1016/j.jallcom.2016.05.168

Novel BiOCl/Ag₂CO₃ hybrid photocatalysts were facilely fabricated in situ precipitation method. The as-prepared samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (FE-SEM), X-ray diffra

Full text of DOI:10.1016/j.jallcom.2016.05.168

Accepted Manuscript
In-situ precipitation synthesis of novel BiOCl/Ag CO hybrids with highly efficient
2
3
visible-light-driven photocatalytic activity
Shanshan Fang, Chaoying Ding, Qian Liang, Zhongyu Li, Song Xu, Yanyan Peng,
Dayong Lu
PII:
S0925-8388(16)31501-8
10.1016/j.jallcom.2016.05.168
JALCOM 37688
DOI:
Reference:
To appear in: Journal of Alloys and Compounds
Received Date: 6 January 2016
Revised Date: 12 May 2016
Accepted Date: 16 May 2016
Please cite this article as: S. Fang, C. Ding, Q. Liang, Z. Li, S. Xu, Y. Peng, D. Lu, In-situ precipitation
synthesis of novel BiOCl/Ag CO hybrids with highly efficient visible-light-driven photocatalytic activity,
2
3
Journal of Alloys and Compounds (2016), doi: 10.1016/j.jallcom.2016.05.168.
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In-Situ Precipitation Synthesis of Novel
BiOCl/Ag2CO3 Hybrids with Highly Efficient
Visible-Light-Driven Photocatalytic Activity
Shanshan Fanga, Chaoying Dinga,b, Qian Lianga, Zhongyu Lia,c,d*, Song Xua*,
Yanyan Pengd, Dayong Lud
a Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology,
School of Petrochemical Engineering, Changzhou University, Changzhou 213164, PR
China
b College of Hua Loogeng, Changzhou University, Changzhou 213164, PR China
c Key Laboratory of Regional Environment and Ecoremediation (Ministry of
Education), Shenyang University, Shenyang 110044, PR China
dJilin Institute of Chemical Technology, Jilin 132022, PR China
* Corresponding author. Tel.: +86-519-86334771; Fax: +86-519-86334771
E-mail address: zhongyuli@mail.tsinghua.edu.cn; cyanine123@163.com

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Abstract
Novel BiOCl/Ag2CO3 hybrid photocatalysts were facilely fabricated in situ
precipitation method. The as-prepared samples were characterized by transmission
electron microscopy (TEM), scanning electron microscopy (FE-SEM), X-ray
diffraction (XRD), Raman spectroscopy, UV-vis diffuse reflectance spectra (DRS),
Fourier transform infrared spectra (FT-IR) and photoluminescence (PL). The
photocatalytic experiments indicated that the as-prepared BiOCl/Ag2CO3
photocatalyst exhibited significantly enhanced photocatalytic activity than the pure
BiOCl and Ag2CO3 samples toward degrading Rhodamine B (RhB) under
visible-light irradiation. Moreover, the photocatalytic mechanism of BiOCl/Ag2CO3
hybrid was also discussed. The remarkably improved photocatalytic performance
should be ascribed to the heterostructure between Ag2CO3 and BiOCl, which greatly
promoted the photoinduced charge transfer and inhibited the recombination of
electrons and holes.
Keywords: BiOCl/Ag2CO3 hybrids; Visible-light photocatalyst; Photocatalytic
activity; In-situ precipitation method
1. Introduction
Energy conversion and environmental accountability are two major challenges to
the sustainable development of human society. Over the past decades the various
advancements in the field of semiconductor-based photocatalysis have received
considerable and prime attention, with a focus on solving environment and energy
related issues [1-3]. The oldest and traditional semiconductor photocatalysts such as

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TiO2 and ZnO have been extensively studied for such a purpose, they exhibit
considerable photocatalytic activity only under UV light (2-4% of the solar spectrum),
which greatly limits the practical application for solar energy conversion [2, 4].
Great efforts have been made to develop visible-light-induced photocatalysts in order
to utilize solar energy more efficiently.
Until now, a variety of visible-light-driven photocatalysts have been reported, such
as g-C3N4 [5, 6], Bi-based photocatalysts [7-9], Ag-based compounds [10-15],
plasmonic noble metal (gold, silver) nanoparticles [16], etc. Among which, Ag-based
photocatalysts are believed to be promising photocatalysts with high efficiency and
have been identified to be well-known photosensitive materials in recent years,
including Ag3PO4 [10], Ag3VO4 [11], Ag2O [12], and AgX (X=Cl, Br, I) [13-15].
More recently, Ag2CO3 semiconductor has been reported for its high-efficient
degradation ability for dyes under visible light [17, 18]. Unfortunately, owing to the
photocorrosion, the Ag2CO3 semiconductor also exhibits poor stability. To solve this
problem, Ag2CO3 has been coupled with other semiconductors with matching band
potential to form a heterojunction at the interface, thus producing Ag2O/Ag2CO3 [19],
Ag2CO3/g-C3N4 [20], AgBr/Ag2CO3 [21], AgI/Ag2CO3 [22], Ag2CO3/ZnO [23],
Ag2CO3/TiO2 [24], which exhibit better photocatalytic ability and stability than the
bare Ag2CO3. These results suggest that heterojunction structure can reduce the
recombination of photogenerated charge carriers, and further improve the
visibe-light-responsive photocatalytic activity of Ag-based composites.
As we all know, BiOCl, is another kind of wide gap bismuth salt, and has the

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internal structure of [Bi2O2]2+ layers interleaved by double slabs of Cl ions, which has
been demonstrated to show efficient photocatalytic performance under simulated
sunlight irradiation [25, 26]. However, due to its large indirect band gap of about 3.50
eV, the pure BiOCl has limited photocatalytic activity under sunlight. Moreover, the
rapid recombination of photoinduced electrons and holes greatly lowers the quantum
efficiency [27]. To further improve the photocatalytic of BiOCl, many studies have
highlighted the means of controlling the microstructure and morphology [28], or
doping some elements, compositing it with other semiconductors [27, 29]. Li et al.
[30] synthesized BiOCl/Bi24O31Cl10 heterojunction with highly efficient activity
through a self-combustion of ionic liquids route. To the best of our knowledge, there
is no investigation focused on the BiOCl/Ag2CO3 hybrids for the degradation of dyes.
In this work, the BiOCl/Ag2CO3 hybrids were synthesized by a facile in situ
precipitation method. The as-prepared samples showed relatively high visible-light
photocatalytic activities for the photodegradation of RhB in aqueous solution.
Accordingly, the possible photocatalytic mechanism was proposed.
2. Experimental
2.1 Synthesis of BiOCl
All the reagents are analytical grade and used without further purifications. Briefly,
5.2088 g Bi(NO3)3•5H2O and 1.4912 g KCl were dissolved in 80 mL ethylene glycol,
respectively. Then KCl solution was added into Bi(NO3)3 solution and the mixture
was stirred for 1 h and then transferred into 200 mL Teflon-lined stainless steel
autoclave and maintained at 160 °C for 12 h. The products were washed once with

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ethanol and three times with distilled water and dried at 60 °C for 5 h.
2.2 Synthesis of Ag2CO3
The Ag2CO3 sample was synthesized by a simple ion exchange method. In a typical
procedure, 40 mL of silver nitrate aqueous solution (0.1 M) was placed in a beaker
and an aqueous solution of solution of sodium bicarbonate (0.05 M) was added
dropwise under stirring condition at room temperature. After continuous stirring for
24 h in the dark, the obtained yellowish green precipitation was collected by
centrifugation and washed with double distilled water followed by ethanol for several
times. Then the product was dried in an oven at 80 °C for 2 h.
2.3 Fabrication of the BiOCl/Ag2CO3 hybrids
The BiOCl/Ag2CO3 hybrids were fabricated by an in situ precipitation strategy. An
appropriate amount of BiOCl was ultrasonicated in 50 mL of water for 2 h. To this
suspension, 0.85 g of silver nitrate was added and stirred for 1 h in the dark.
Subsequently, 50 mL of 0.05 M sodium bicarbonate aqueous solution was added
dropwise and stirred for 24 h in the dark. The obtained precipitation was centrifuged,
washed with double distilled water followed by ethanol for several times and finally
dried at 80 °C for 6 h. A series of BiOCl/Ag2CO3 hybrids were synthesized with
different weight ratios of BiOCl and 5, 7.5, 10, 12.5 and 15 wt% BiOCl samples are
denoted as 5%-BiOCl/Ag2CO3, 7.5%-BiOCl/Ag2CO3, 10%-BiOCl/Ag2CO3,
12.5%-BiOCl/Ag2CO3 and 15%-BiOCl/Ag2CO3, respectively.
2.4 Characterization
The XRD, TEM, SEM, FT-IR, PL, Raman and UV-vis absorption spectra were used

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to characterize as-prepared samples. The crystalline catalyst was examined by X-ray
diffraction (XRD) under a Rigaku D/Max-2500PC X-ray diffractometer (Rigaku Co.,
Japan) employing Cu Kα radiation, λ = 1.54056 Å operated at 40 kV and 100 mA. A
JEM-2100 transmission electron microscope (TEM) and a JSM-6360LA scanning
electron microscope (SEM, JEOL, Japan) were used to characterize the morphology
of the samples. Fourier transform infrared spectra (FT-IR) was recorded in the
wavenumber range from 400 to 4000cm-1 by Nicolet (PROTéGé 460) spectrometer.
Raman spectra were measured at room temperature using a LabRAM XploRA Raman
spectrometer (Horiba Jobin Yvon, France) with a 532 nm laser focused on a spot
about 3 ꢀm in diameter. UV-vis diffuse reflectance spectroscopy (DRS) spectra of the
photocatalysts were measured by a UV-vis scanning spectrophotometer (Shimadzu
UV-2550) using an integrating sphere and BaSO4 as white standard. The
photoluminescence (PL) spectra were obtained by an F-280 spectrometer (Tianjin
Keqi, China)..
2.5 Photocatalytic activity
The photocatalytic activity of the BiOCl/Ag2CO3 samples was evaluated by
degradation of Rhodamine B (RhB) solution under visible light irradiation. A 1 kW
Xe lamp was used as the light source. In each experiment, 40 mg of the as-prepared
photocatalyst was added into 50 ml of RhB solution (15 mg/L). Before irradiation, the
suspensions were placed in dark and stirred for 30 min to ensure the establishment of
adsorption-desorption equilibrium between the catalyst and RhB. Subsequently, at
intervals of every 20 min, about 5 mL of suspension was samples and centrifuged to

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remove the photocatalyst particles. The concentration of filtrates was analyzed by
measuring the maximum absorbance at 553 nm for RhB using a UV759 UV-vis
spectrometer (Shanghai Precision & Scientific Instrument Co., Ltd., China). The
decomposition efficiency of the target contaminant was calculated by D = (1 - Ct/C0)
× 100%, where C0 and Ct are the equilibrium concentration of the target contaminant
before and after visible-light irradiation, respectively.
3. Results and discussion
3.1 XRD patterns
XRD studies were carried out to investigate the phase structure and crystalline
nature of the synthesized samples. The XRD patterns of BiOCl, Ag2CO3 and the
as-prepared BiOCl/Ag2CO3 hybrids with different content of BiOCl are shown in Fig.
1. The sharp and intense diffraction peaks of the as-prepared samples indicated that all
the samples were well crystalline. The characteristic diffraction peaks were detected
at 2θ angles of 23.9°, 25.8°, 32.5°, 33.3°, 40.8°, 46.6°, 49.6°, 54.1°, 58.5° and 68.1°
corresponding to the (002), (101), (110), (102), (112), (200), (113), (211), (212) and
(220) crystal planes of pure BiOCl could be indexed to the tetragonal phase of BiOCl
(JCPDS no. 06-0249), suggesting the high purity. In addition, pure Ag2CO3 displays
sharp diffraction peaks (from 15º to 55º) are indexed to (020), (110), (101), (130),
(200), (031), (220), (131), (230) and (221) planes of the monoclinic crystal structure
(JCPD card no. 26-0339). No other impurities were found, including metallic silver,
thus indicating the purity of the as-prepared Ag2CO3. Moreover, following the
increase in content of the BiOCl, the intensity of the diffractions of BiOCl displayed

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improvement. It was also found that the intensity of peaks at 2θ = 24.02º and 46.6º are
attributed to BiOCl in the BiOCl/Ag2CO3 hybrids. These results could confirm that
BiOCl combined with Ag2CO3 closely and that interactions existed between the
photocatalytic semiconductors.
3.2 FE-SEM images
The FE-SEM morphology and size of samples are observed as shown in Fig. 2. In
Fig. 2a, the pure BiOCl appear as two-dimensional sheet-like nanostructures with
uniform thickness of about 40-50 nm and of relatively smooth surface. Fig. 2b shows
that the morphology of as-synthesized Ag2CO3 was composed of microcuboids with a
length of 0.3-1.0 ꢀm. Fig. 2c revealed that the two types of materials were all found in
the sample of 10%-BiOCl/Ag2CO3, and the BiOCl microsphere were assembled on
the surface of the Ag2CO3 nanocuboids. Obviously, the coexistence of BiOCl and
Ag2CO3 does not change their respective morphology. This result further
demonstrated the successful synthesis of BiOCl/Ag2CO3 hybrids photocatalyst.
3.3 TEM images
Moreover, the crystal structure of the pure BiOCl, Ag2CO3 and the
10%-BiOCl/Ag2CO3 hybrid were further investigated by TEM and the HRTEM (Fig.
3). In Fig. 3a, BiOCl exhibits a hierarchical flower-like structure with a diameter of
1-2 ꢀm composed of nanosheets. Fig. 3b displays that the Ag2CO3 has regular
nanoparticle morphology and a relatively smooth surface. From Fig. 3c, it can be seen
that BiOCl closely adhered to the surface of the Ag2CO3, resulting in intimate contact,
which was beneficial to separate the photogenerated charge carriers. The HRTEM

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image of the 10%-BiOCl/Ag2CO3 photocatalyst is shown in Fig. 3d. The clear lattice
stripe indicated that these samples were well crystallized, and the distance of the
lattice fringes is 0.273 nm and 0.267 nm respectively, which match well with the
interplanar spacing of (2 0 0) and (1 0 2) lattice plane of BiOCl.
3.4 UV-vis diffuse reflectance spectra
The light absorption abilities of the as-prepared samples at different light
wavelengths were investigated by UV-Vis diffuse reflectance spectroscopy, and the
results were recorded in Fig. 4a. The absorption band edges of pristine BiOCl and
Ag2CO3 were estimated to be 375 nm and 470 nm, respectively. It displayed that the
as-prepared BiOCl and Ag2CO3 both had strong and broader absorption in the visible
light region, suggesting their potential capabilities in the effective utilization visible
light energy. With the increasing BiOCl content, the BiOCl/Ag2CO3 hybrids exhibited
obviously red-shifted compared with Ag2CO3. More interestingly, the absorption
intensities of all the BiOCl/Ag2CO3 hybrids showed a significant enhancement in the
wavelength range of 500-800 nm compared with BiOCl and Ag2CO3. It can be
attributed to the synergetic effect between BiOCl and Ag2CO3. In the photocatalytic
reaction, light-absorbing property of the samples was crucial for the photocatalysis.
The band gap of the as-prepared samples was calculated by a related curve of
(Ahv)1/2 versus photon energy (A = absorption coefficient, h = Planck’s constant, m =
frequency) plotted, from the intersection of the extrapolated linear portion. The value
of BiOCl, Ag2CO3 and BiOCl/Ag2CO3 hybrids (different BiOCl content) was
estimated to be 3.41 eV, 2.35eV, 1.72 eV, 1.71 eV, 1.60 eV, 1.65 eV and 1.69 eV,

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respectively (Fig. 4b). This reveals that the band gap of BiOCl/Ag2CO3 hybrids is
smaller than that of pure BiOCl and Ag2CO3, and these results also support that all
these BiOCl/Ag2CO3 hybrids have suitable band gaps to be activated by visible-light
for photocatalytic decomposition of organic contaminants.
3.5 FT-IR analysis
In order to attain a better insight for the chemical structures of as-prepared samples,
FTIR analysis was carried out. As shown in Fig. 6, the broad and strong peak in the
range of 3200-3550 cm-1 may belong to the stretching vibrations of –OH of adsorbed
water molecules, while, the obvious absorption at 1637 cm-1 can be ascribed to
deformation vibrations of the –OH groups of adsorbed water molecules [31]. For pure
Ag2CO3, the peaks appearing at 1386 and 887 cm-1 are attributed to the characteristic
2-
absorption bands of CO3 [32]. The representative absorption band of pure BiOCl
could be found at 519 cm-1 which was assigned to the Bi-O bond stretching vibration
[33-34]. Nevertheless, the FT-IR spectra of BiOCl/Ag2CO3 hybrids are similar to
those of the main peaks of pure BiOCl and Ag2CO3. Based upon the FT-IR analysis,
we can deduce that as-synthesized hybrids consist of two components of BiOCl and
Ag2CO3 which maintain their original main hybridized structures.
3.6 Raman spectra
Raman spectra of BiOCl, Ag2CO3 and 10%-BiOCl/Ag2CO3 hybrids are shown in
Fig.6. It was found that pure BiOCl showed two distinctive bands and one weak band.
The strong band at 144 cm−1 and the band at 197 cm−1 can be assigned to the A1g
internal Bi-Cl stretching mode and the Eg internal Bi-Cl stretching mode, respectively.

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The Eg external Bi-Cl stretching was probably overlapped by the strong band at 144
cm−1. The weak band at 396 cm−1 can be ascribed to Eg and B1g band, produced by the
movement of the oxygen atoms [35]. The Raman spectra of Ag2CO3 display four
characteristic peaks located at approximately 710 cm−1, 926 cm−1, 1070 cm−1,
1400cm−1. After the introduction of BiOCl in the BiOCl/Ag2CO3 hybrids, the
intensity of the characteristic peaks showed a significant decrease, which may be due
to the wrapped BiOCl on the surface of Ag2CO3. Not only the typical Raman peaks of
BiOCl were located at about 143 cm−1, but also the Ag2CO3 typical peaks of at 1070
cm−1, indicating the formation of BiOCl/Ag2CO3 hybrids.
3.7 Photocatalytic activity of BiOCl/Ag2CO3 hybrids
To evaluate the photocatalytic properties of pure BiOCl, Ag2CO3 and
BiOCl/Ag2CO3, RhB was degraded as a model dye over these photocatalysts under
visible-light irradiation at room temperature. Fig. 7a shows the time-dependent
absorption spectra of RhB solution in the presence of 10%-BiOCl/Ag2CO3 hybrid
sample. Under visible-light illumination, the color of RhB solution changed gradually
from red to colorless during the reaction. The intensity of the absorption peak at 553
nm decreased drastically within 100 min. The degradation efficiency reached 97%
after 100 min, which indicated that the 10%-BiOCl/Ag2CO3 sample exhibited high
photocatalytic activity.
As shown in Fig. 7b, all BiOCl/Ag2CO3 hybrid photocatalysts exhibit better
photodegradation performance than the pure BiOCl and Ag2CO3. Following the
increasing BiOCl content, the photocatalytic activity of BiOCl/Ag2CO3 gradually

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improved. BiOCl/Ag2CO3 exhibited the highest photocatalytic degradation efficiency
when BiOCl content reached to 10 wt%. However, the photocatalytic activity of
BiOCl/Ag2CO3 samples decreased when the BiOCl content was more than 10 wt%. It
suggested that the optimal content of BiOCl in hybrid photocatalyst was 10 wt%.
More BiOCl may reduce the electron transfer efficiency of the photoinduced electrons
from Ag2CO3 nanoparticles to BiOCl surfaces, so the activity decreased under
visible-light irradiation.
Fig. 7c reveals that the photocatalytic degradation of RhB on different catalysts fits
pseudo-first-order kinetics, ln(C0/Ct) =kappt, where t is the irradiation time and kapp is
the rate constant. It can be seen that the photodegradation rates of all the
BiOCl/Ag2CO3 hybrids are much higher than that of the pure Ag2CO3 and BiOCl
under visible-light. Concretely, the kapp for RhB degradation with Ag2CO3, BiOCl,
5%-BiOCl/Ag2CO3, 7.5%-BiOCl/Ag2CO3, 10%-BiOCl/Ag2CO3, 12.5%-BiOCl/
Ag2CO3, and 15%-BiOCl/Ag2CO3 were estimated to be 0.0004 min-1, 0.0034 min-1,
0.0063 min-1, 0.0127 min-1, 0.0314 min-1, 0.0261 min-1 and 0.0111 min-1, respectively.
These results clearly demonstrated that the BiOCl/Ag2CO3 hybrid photocatalysts
system can significantly enhance their photocatalytic activities because of the
synergistic effect between BiOCl and Ag2CO3.
3.8 PL analysis
In general, photoluminescence emission spectroscopy (PL) is considered as an
effective technology to investigate the migration, transfer and recombination process
of photo-generated charge carriers in semiconductors. The higher PL intensity

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represents the lower separation capacity of photoinduced charge carriers and the lower
photocatalytic activity in semiconductor-based systems. Fig. 8 shows the PL spectra
of the synthesized pure Ag2CO3, BiOCl microsphere and BiOCl/Ag2CO3 hybrids
recorded at room temperature with an excitation wavelength of 300 nm. The
BiOCl/Ag2CO3 hybrid photocatalysts exhibited the emission peaks locating at almost
the same position with the pure Ag2CO3. However, emission intensities decreased,
which suggested that BiOCl/Ag2CO3 hybrids had much lower recombination rate of
photogenerated charge carriers. The intensity of the 10%-BiOCl/Ag2CO3 hybrid
photocatalyst was the lowest among other photocatalysts, indicating that the
10%-BiOCl/Ag2CO3 hybrid had a lowest recombination rate of photo-generated
charge carriers. According to the above results, the recombination of photogenerated
charge carriers was greatly inhibited in the heterostructured BiOCl/Ag2CO3,
demonstrating the as-prepared BiOCl/Ag2CO3 hybrids possessed higher separation
efficiency than the pure BiOCl and Ag2CO3.
3.9 Photocatalytic mechanism
¯
In the photodegradation process of organic pollutants, reactive species ·O2 , h+ and
·OH acted as a bridge, playing the role of photocatalysts under the light irradiation,
therefore, it is necessary to determine the main reactive species for the degradation of
RhB in this study. Some sacrificial agents, such as iso-propyl alcohol (IPA), disodium
ethylenediaminetetraacetate (EDTA) and 1, 4-benzoquinone (BQ) were used as the
¯
scavengers of hydroxyl radical (·OH), hole (h+) and superoxide radical (·O2 ),
respectively. Fig. 9 shows that the photodegradation efficiency of RhB over

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10%-BiOCl/Ag2CO3 is not affected by the addition of BQ, indicating that almost no
¯
superoxide radicals (·O2 ) were involved in the degradation of RhB. When IPA was
added, the photodegradation efficiency of RhB obviously decreased, which revealed
the existence of ·OH radical species. Besides, the photocatalytic activity was
thoroughly suppressed by addition of EDTA, suggesting that the h+ pathways play a
crucial role in the process of RhB degradation. These results indicated that the h+ and
·OH were the main active species in the RhB photodegradation process.
Based on the above analysis, the schematic mechanism of the enhanced
photocatalytic activity of the BiOCl/Ag2CO3 hybrids is proposed and shown in Fig.
10. According to previously reported results [36, 37], the EVB values of Ag2CO3 and
BiOCl were calculated to be 2.67 and 2.4 eV, and then their homologous ECB values
were estimated to be 0.37 and -1.1 eV, respectively. Upon exposure to the visible-light,
both BiOCl and Ag2CO3 are simultaneously excited to generate electron-hole pairs.
The photoexcited electrons on less positive conduction band of BiOCl would prefer to
flow down to the more positive conduction band of Ag2CO3, while the photogenerated
holes would flow from more positive valence band of Ag2CO3 to less positive valence
band of BiOCl. Besides, Due to the more positive VB level of Ag2CO3 than that of
·OH/OH−, some remained h+ could be transformed into ·OH by oxidizing OH− that
absorbed on the surface of the photocatalysts. Thus, the h+ and ·OH were the two
active species and play the crucial roles for photodecomposition of RhB. The charge
transfer effectively inhibited the recombination of photogenerated electron-hole pairs
and thus enhanced the photocatalytic activity.

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In addition, the XRD patterns of the sample before and after the reaction (Fig. 11)
showed that the crystal structure had little change and no additional band appeared
during the photodegradation process. These suggested that the as-prepared
BiOCl/Ag2CO3 hybrid were not photocorroded and presented relatively high stability.
4. Conclusions
In summary, the BiOCl/Ag2CO3 visible-light-induced photocatalyst was fabricated
by facile in situ precipitation method. The photocatalytic experiments demonstrated
that the BiOCl/Ag2CO3 hybrids exhibit the much better photocatalytic performance
than the individual compounds in degradation of RhB under visible-light irradiation.
The remarkable photocatalysis enhancement can be attributed to the effective
separation of photogenerated electrons–hole pairs, which was due to the
heterostructure formed between the two semiconductors. Therefore, the facile process
using BiOCl/Ag2CO3 heterojunction could be an efficient strategy for the destruction
of environmental pollutants.
Acknowledgments
This work was financially supported by Open Fund of Key Laboratory of Regional
Environment and Eco-remediation of Ministry of Education, China (SYU-KF-E-12),
Open Fund of Key Laboratory of Contaminated Environment Control and Regional
Ecology Safety, Shenyang University (SYU-KF-L-12), Natural Science Foundation of
Jiangsu Province, China (No. BK20150259), Project for Six Major Talent Peaks of
Jiangsu Province (2011-XCL-004) and Natural Science Foundation of Changzhou
City (CJ20140053).

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Figures captions
Fig. 1. XRD patterns of pure BiOCl, Ag2CO3 and series of BiOCl/Ag2CO3 hybrids.
Fig. 2. FE-SEM images of the pure BiOCl (a), Ag2CO3 (b), as-prepared
10%-BiOCl/Ag2CO3 hybrids (c).
Fig. 3. TEM images of the pure BiOCl (a), Ag2CO3 (b), and higher magnification
TEM image of 10%-BiOCl/Ag2CO3 hybrids (c, d).
Fig. 4. UV-vis diffuse reflectance spectra (a), and band gap width (b) of BiOCl,
Ag2CO3 and series of BiOCl/Ag2CO3 hybrids.
Fig. 5. FT-IR of pure BiOCl, Ag2CO3 and 10%-BiOCl/Ag2CO3 hybrids.
Fig. 6. Raman spectra of as-prepared BiOCl, Ag2CO3 and 10%-BiOCl/Ag2CO3
hybrids.
Fig. 7. (a) Temporal evolution of the spectra during the photodegradation of RhB over
10%-BiOCl/Ag2CO3 sample; (b) photodegradation of RhB with BiOCl, Ag2CO3 and
BiOCl/Ag2CO3 hybrids under visible-light irradiation; (c) kinetic data for the
degradation of RhB in the presence of different photocatalysts.
Fig. 8. PL spectra of pure BiOCl, Ag2CO3 and series of BiOCl/Ag2CO3 hybrids.
Fig. 9. Effects of different scavengers on the degradation of RhB in the presence of
10%-BiOCl/Ag2CO3 under visible-light irradiation.
Fig. 10. Proposed mechanism for the photodegradation of RhB over BiOCl/Ag2CO3
hybrids under visible-light irradiation.
Fig. 11. XRD pattern of the 10%-BiOCl/Ag2CO3 before and after the long time
experiment.

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♦
200000
160000
120000
80000
40000
0
♦
♦
♦
♦
♦
♦
♦
♦
♦
Ag2CO3
15%-BiOCl/Ag2CO3
12.5%-BiOCl/Ag2CO3
10%-BiOCl/Ag2CO3
7.5%-BiOCl/Ag2CO3
•
•
5%-BiOCl/Ag2CO3
BiOCl
( 2 0 0)•
40
( 0 0 2)
20
•
10
30
50
60
70
80
2 Theta (degree)
Figure 1

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Figure 2

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Figure 3

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5%-BiOCl/Ag CO
2
3
1.5
1.0
0.5
0.0
( a)
7.5%-BiOCl/Ag CO
2
3
10%-BiOCl/Ag CO
2
3
12.5%-BiOCl/Ag CO
2
3
15%-BiOCl/Ag CO
2
3
BiOCl
Ag CO
2
3
300
400
500
600
700
800
Wavelength/nm
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
( b)
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
5%-BiOCl/Ag CO
2
3
7.5%-BiOCl/Ag CO
2
3
10%-BiOCl/Ag CO
2
3
12.5%-BiOCl/Ag CO
2
3
15%-BiOCl/Ag CO
2
3
BiOCl
Ag CO
2
3
2.0
2.5
3.0
3.5
4.0
4.5
5.0
hv( eV)
Figure 4

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Ag2CO3
200
150
100
50
10%-BiOCl/Ag2CO3
BiOCl
0
4000
3500
3000
2500
2000
1500
1000
500
-1
cm
Wavenumber
(
)
Figure 5

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12000
10000
8000
6000
4000
2000
0
Ag CO
2
3
BiOCl
10%-BiOCl/Ag CO
2
3
200
400
600
800
1000
1200
1400
-1
Raman shift ( cm £
Figure 6

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1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
( a )
t=0
t=20min
t=40min
t=60min
t=80min
t=100min
400
500
600
700
800
100
100
Wavelength/nm
1.0
0.8
0.6
0.4
0.2
0.0
( b )
5%-BiOCl
7.5%-BiOCl
10%-BiOCl
12.5%-BiOCl
/
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
/
/
/
15%-BiOCl
/
BiOCl
Ag2CO3
0
20
40
60
80
Time/min
5%-BiOCl/Ag2CO3 k=0.0063
7.5%-BiOCl/Ag2CO3 k=0.0127
10%-BiOCl/Ag2CO3 k=0.0314
12.5%-BiOCl/Ag2CO3 k=0.0261
15%-BiOCl/Ag2CO3 k=0.0111
( c )
3
2
1
0
BiOCl
Ag2CO3
k=0.0034
k=0.0004
0
20
40
60
Time (min)
80
Figure 7

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3500
3000
2500
2000
1500
1000
500
Ag2CO3
BiOCl
5%-BiOCl/Ag2CO3
7.5%-BiOCl/Ag2CO3
10%-BiOCl/Ag2CO3
12.5%-BiOCl/Ag2CO3
15%-BiOCl/Ag2CO3
0
350
400
450
500
Wavelength/nm
Figure 8

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0.04
0.03
0.02
0.01
0.00
1.0
0.8
no scavenger
BQ
0.6
0.4
0.2
0.0
no scavenger
EDTA
BQ
IPA
0
20
40
60
80
100
Time/min
IPA
EDTA
Scavengers
Figure 9