Facile microwave synthesis of 3D flowerlike BiOBr nanostructures and their excellent CrVI removal capacity

Article abstract of DOI:10.1002/ejic.201101427

A facile and fast microwave irradiation method has been developed to synthesize uniform well-defined 3D flowerlike BiOBr nanostructures through a self-assembly process. Cetyltrimethylammonium bromide (CTAB), which acts as both the bromide source and soft template, plays a critical role in the formation of 3D flowerlike BiOBr nanostructures. Different flowerlike BiOBr nanostructures could be obtained by varying the CTAB concentration. A possible formation process is discussed. The as-prepared flowerlike BiOBr nanostructures possessed a large surface area and exhibited an excellent removal capacity and fast adsorption rate for Cr^VI ions in a wide pH range. Copyright

Full text of DOI:10.1002/ejic.201101427

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FULL PAPER
DOI: 10.1002/ejic.201101427
Facile Microwave Synthesis of 3D Flowerlike BiOBr Nanostructures and Their
Excellent CrVI Removal Capacity
Guangfang Li,[a] Fan Qin,[a] Hao Yang,[a] Zhong Lu,[a] Hongzhe Sun,[b] and Rong Chen*[a]
Keywords: Bismuth oxybromide / Nanostructures / Templated synthesis / Microwave chemistry / Chromium
A facile and fast microwave irradiation method has been
developed to synthesize uniform well-defined 3D flowerlike
Different flowerlike BiOBr nanostructures could be obtained
by varying the CTAB concentration. A possible formation
process is discussed. The as-prepared flowerlike BiOBr nano-
structures possessed a large surface area and exhibited an
excellent removal capacity and fast adsorption rate for CrVI
ions in a wide pH range.
BiOBr nanostructures through
a self-assembly process.
Cetyltrimethylammonium bromide (CTAB), which acts as
both the bromide source and soft template, plays a critical
role in the formation of 3D flowerlike BiOBr nanostructures.
cause of its unique electrical, magnetic, and optical proper-
ties, as well as its promising application in environmental
remediation. Nanostructured BiOBr demonstrates not only
excellent photocatalytic activity for NO oxidation, degrada-
tion of organic pollutants, and sterilization, but also an ef-
fective adsorption ability for organic dyes.[16–19] Various Bi-
OBr micro/nanostructures, which include nanoparticles,[20]
nanobelts, nanotubes,[21,22] nanoplates, and micro-
sheets,[23,24] have been successfully fabricated by means of
microemulsion, solvothermal, and sol-gel method. Apart
from this, 3D hierarchically nanostructured BiOBr, which
includes microspheres and microflowers, has also been syn-
thesized by solvothermal method.[15,25–28] Unfortunately,
these fabrications led to characteristic crystalline structures,
which thus showed significant differences in their perform-
ance. For example, almost all of the obtained 3D BiOBr
hierarchical structures are closely packed and are domi-
nated by large crystal size or irregular shape, which severely
limit its potential adsorptive ability as well as its catalytic
performance. In addition, the reported synthetic strategies
suffered from the drawbacks of harsh conditions, long reac-
tion times, and complexity. Thus, a facile and fast approach
is highly desirable for the fabrication of diverse well-defined
BiOBr hierarchical nanostructures. Recently, microwave ir-
radiation method has been successfully developed to be a
facile, fast, and mild synthetic route for the fabrication of
various nanomaterials with controllable shape and
Introduction
The controlled synthesis of nanostructures with unique
size and shape-dependent properties has attracted increas-
ing attention during the past decades. In particular, the de-
sign and fabrication of three-dimensional (3D) hierarchical
nanostructures are of great interest and are being inten-
sively pursued by virtue of their broad application in bio-
medical fields, energy storage, and catalysis.[1–5] Recently,
it was also found that 3D hierarchical nanostructures with
porous and hollow structures exhibited excellent perform-
ance in the removal of heavy metal ions as highly effective
adsorbents. Compared with the corresponding bulk materi-
als and traditional adsorbents, hierarchical nanostructures
possess improved removal capacity and a faster adsorption
rate owing to their large surface area, special surface prop-
erty, and so forth.[6–11] Consequently, more research work
focused on the fabrication and application of 3D hierarchi-
cal nanostructures. In the literature, most of the 3D nano-
structures have been fabricated by a solvothermal strategy
with the assistance of biomolecule, hard template, and mi-
croemulsion.[1,12–15] Hence, it is still a challenge to develop
simple and reliable synthetic methods for 3D nanostruc-
tures with the desired morphology.
As an important V–VI–VII ternary compound, bismuth
oxybromide (BiOBr) has been extensively investigated be-
[a] Key Laboratory for Green Chemical Process of Ministry of size.[29–32] It offers the advantage of uniform and dielectric
Education and School of Chemical Engineering & Pharmacy,
heating without thermal gradient effects, which promote the
Wuhan Institute of Technology,
reaction rate and led to an important advancement in the
large-scale production of nanomaterials.
Xiongchu Avenue, Wuhan, 430073, P.R. China
Fax: +86-2787194465
E-mail: rchenhku@hotmail.com
In this work, we report for the first time the successful
synthesis of well-defined flowerlike BiOBr hierarchical
nanostructures by a facile and fast microwave irradiation
method. The obtained flowerlike BiOBr nanostructure pos-
sesses a highly specific surface area and large pore volume.
[b] Department of Chemistry and Open Laboratory of Chemical
Biology of the Institute of Molecular Technology for Drug
Discovery and Synthesis, The University of Hong Kong,
Pokfulam Road, Hong Kong SAR, China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201101427.
Eur. J. Inorg. Chem. 0000, 0–0
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G. Li, F. Qin, H. Yang, Z. Lu, H. Sun, R. Chen
FULL PAPER
As an example of its potential application in environmental mation). The ratio of the bismuth, bromide, and oxygen
remediation, the as-synthesized flowerlike BiOBr nano- elements is approximately 1:1:1, which is in good agreement
structure was used as an adsorbent in water treatment and with the stoichiometry of BiOBr.
exhibited an excellent removal capacity for CrVI ions, which
has not been reported in previous studies.
In this fabrication BiOBr was obtained under different
CTAB concentrations (3–30 mm) as confirmed by its XRD
patterns (Figure S2, Supporting Information). When the
CTAB concentration was lower than 3 mm, no BiOBr prod-
uct was collected. It was also found that CTAB played a
unique role in controlling the morphology and size of
the BiOBr nanostructure. Different flowerlike BiOBr nano-
structures could be formed when the CTAB concentration
was in the range of 3 to 16 mm (S2–S4). The typical SEM
and TEM images of BiOBr products prepared in different
CTAB concentrations are depicted in Figure 2. It is clear
that the variation of CTAB concentration in this synthesis
led to a dramatic change in the shape and size of the ob-
tained BiOBr flowerlike nanostructures. When the CTAB
concentration was 3 mm, SEM and TEM images revealed
that well-defined flowerlike nanostructures with a uniform
diameter of 350 nm were fabricated, which consisted of
dozens of thin petals (S2, Figures 2a and 2b). With an in-
crease in the CTAB concentration to 8 mm, the size of the
flowerlike nanostructures decreased to about 150 nm in dia-
meter (S3, Figures 2c and 2d). However, irregular flowerlike
structures with fewer petals and a diameter of ca. 110 nm
were obtained in the presence of 16 mm CTAB solution (S4,
Figures 2e and 2f). When the CTAB concentration was
higher than 16 mm, there was an obvious tendency to form
bulk agglomeration (S5, Figure S3, Supporting Infor-
Results and Discussion
Structure and Morphology of BiOBr Nanostructures
The X-ray powder diffraction (XRD) pattern of the as-
prepared product (S1) is shown in Figure 1a. All of the dif-
fraction peaks could be readily indexed to pure tetragonal
phase BiOBr (JCPDS 73-2061) with a space group of P4
(No. 129) and lattice constants of a = 3.915 Å and c =
8.076 Å. The diffraction peaks were remarkably broadened,
which might be ascribed to the small crystalline size of the
BiOBr crystals. The scanning electron microscopy (SEM)
image (Figure 1b) of the BiOBr product revealed that the
product is composed of a large quantity of uniform 3D
flowerlike nanostructures with a diameter of 200 to 300 nm.
The transmission electron microscopy (TEM) image is pro-
vided in Figure 1c for further investigation of the detailed
morphology and structure of the flowerlike nanostructure,
which showed that the entire structure is built from thin
petals. These petals are loosely packed and connected to
each other through the center to form flowerlike structures.
A representative high-magnification TEM image taken
from a piece of petal of the flowerlike structure is depicted
in Figure 1d. It clearly revealed that these petals are con-
structed by very small nanoparticles (5–10 nm), which
could explain the broadening of the XRD peaks. The corre-
sponding selected-area electron diffraction (SAED) pattern
illustrated that the as-prepared BiOBr nanostructure has a
highly polycrystalline structure (Figure 1e). The energy dis-
persive X-ray (EDX) analysis also confirmed the formation
of the BiOBr compound (Figure S1, Supporting Infor-
Figure 1. (a) XRD pattern, (b) SEM image, (c) TEM image, (d)
high-magnification TEM image, and (e) SAED pattern of the flow-
erlike BiOBr nanostructures that were fabricated in the presence of
5 mm CTAB (S1).
Figure 2. SEM and TEM images of BiOBr nanostructures synthe-
sized in different CTAB concentrations: (a and b) 3 mm, S2; (c and
d) 8 mm, S3; (e and f) 16 mm, S4.
2
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BiOBr Nanostructures and CrVI Removal Capacity
mation). This indicated that CTAB acted as not only the mation), which indicates that the formation of flowerlike
bromine source but also as a soft template and that proper nanostructures is affected by the reaction temperature.
CTAB concentration facilitated the assembly of petals into However, the influence of the reaction temperature is a
3D flowerlike nanostructures with controllable shape and complicated issue in the microwave synthesis and needs fur-
size through the interaction between the CTAB molecules ther detailed investigation.
and the petals, which is similar to the cases reported in the
In the literature, it was reported that CTAB might form
literature.[9,33] In order to verify the role of CTAB, control spherical micelles, wormlike micelles, or even high-order
experiments were carried out using KBr instead of CTAB. phases. Generally, spherical micelles are dominant in a
However, only platelike BiOBr nanostructures were ob- CTAB solution concentrated over its critical micelle con-
tained in the presence of different KBr concentrations un- centration (CMC) and wormlike micelles predominate at
der the identical reaction conditions (S6–S8, Figure S4, higher concentrations.[34,35] In the present synthesis, a dra-
Supporting Information).
matic variation in the size and shape of flowerlike BiOBr
nanostructures might be due to the different micelle struc-
tures depending on the CTAB concentration. From the ex-
perimental results, a micelle-dependent model was proposed
for the formation of flowerlike BiOBr nanostructures. As
illustrated in Scheme 1, uniform spherical micelle structures
were formed at low CTAB concentrations near CMC,
which were surrounded by BiO+ ions generated from the
bismuth precursor.[2] Under microwave irradiation, BiO+
ions reacted with CTAB to form BiOBr nuclei. In the
growth process that followed, 2D petals were preferentially
formed depending on the intrinsic BiOBr layered struc-
ture.[26] The petals then assembled to construct the well-
defined flowerlike BiOBr nanostructure through the inter-
action between CTAB molecules and the petals. With the
increase of CTAB concentration, wormlike micelles grad-
ually predominated but these micelles break and transfer
into spherical ones when the temperature is increased.[36,37]
Thus, it was imagined that more but smaller spherical mi-
celle structures might be generated from the broken worm-
like micelles at relatively high concentration under micro-
wave heating, which leads to the formation of BiOBr flow-
erlike nanostructures with smaller size and fewer petals.
However, the particles would be totally capped by CTAB
molecules at very high CTAB concentration in the forma-
tion process of BiOBr, which would finally result in the ag-
glomeration (S5). In fact, our present understanding of the
formation of BiOBr flowerlike nanostructures is quite lim-
ited and further investigation is in progress.
Possible Formation Process of Flowerlike BiOBr
Nanostructures
In order to investigate the formation process of the flow-
erlike nanostructure further, time-dependent experiments
were conducted. The SEM images of the products prepared
in the presence of 5 mm CTAB at different reaction times
are displayed in Figure 3. At the early stage (5 min, S9), the
product was composed of BiOBr nanoplates together with
partial flowerlike nanostructures (Figure 3a). After
a
10 min microwave reaction, the amount of flowerlike nano-
structures increased (S10, Figure 3b). As the reaction pro-
ceeded to 20 min, there was a tendency to form flowerlike
nanostructures for the whole sample (S11, Figure 3c).
Eventually, well-defined flowerlike nanostructures were ob-
tained after a 30 min reaction (S1, Figure 3d). This process
involved two stages. Nanopetals formed quickly in the ini-
tial stage, which was followed by a relatively slow aggrega-
tion of the petals into flowerlike nanostructures. In ad-
dition, the reaction temperature is an important parameter
during the fabrication process of BiOBr flowerlike nano-
structures. In this synthesis, different BiOBr flowerlike
nanostructures (S1–S4) were fabricated at the same reaction
temperature (110 °C). At low temperatures (30 or 60 °C),
for instance, only large crystals with irregular morphology
were obtained (S12 and S13, Figure S5, Supporting Infor-
Figure 3. SEM images of BiOBr products obtained at different re-
action times: (a) 5 min, S9; (b) 10 min, S10; (c) 20 min, S11; and
(d) 30 min, S1.
Scheme 1. Illustration of possible formation mechanism of flower-
like BiOBr nanostructures in the presence of different CTAB con-
centrations.
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G. Li, F. Qin, H. Yang, Z. Lu, H. Sun, R. Chen
FULL PAPER
Nitrogen Adsorption–Desorption Isotherm of BiOBr
Nanostructures
of the CrVI ions could be adsorbed within 15 min. The
K2Cr2O7 removal capacity of flowerlike and platelike Bi-
OBr was measured to be 56.2 and 31.4 mgg–1, respectively,
which is much higher than that of the reported nanoscaled
adsorbents.[9,40–42] It was evident that the flowerlike BiOBr
nanostructure showed superior removal capacity, which
should be mainly ascribed to its highly specific surface area
and loosely packed structure.
A nitrogen adsorption–desorption isotherm measure-
ment was conducted to further investigate the structural
characteristics of the flowerlike BiOBr nanostructure ob-
tained in a 5 mm CTAB solution (S1). As shown in Fig-
ure 4a, it displayed a type IV isotherm with a type H3 hys-
teresis loop at high relative pressures between 0.8 and 1.0,
which indicates the presence of mesopores (2–50 nm).[38]
Moreover, the hysteresis loop shifted approach p/p0 ≈ 1,
which demonstrates the presence of large macropores
(Ͼ 50 nm).[39] This was further confirmed by the corre-
sponding Barrett–Joyner–Halenda (BJH) pore diameter
distribution in which the peaks for both mesopores and
macropores up to 100 nm were found (Figure 4b). Con-
sidering the observed morphology and structure of the
product, the smaller pores with sharp peaks at about 2 and
6 nm might be generated during the crystal growth process,
whereas the larger pores with a wide pore diameter distribu-
tion could be attributed to the space between the inter-
crossed BiOBr petals. The Brunauer–Emmett–Teller (BET)
specific surface area of S1 was estimated to be 63.5 m2 g–1,
which is much larger than that of platelike BiOBr nano-
structures (33.6 m2 g–1, Figure S6, Supporting Information).
The large BET surface area, ideal pore size distribution,
and pore volume (0.19 m3 g–1) make the as-obtained BiOBr
flowerlike nanostructure a promising candidate as an ad-
sorbent for heavy metal ion removal in water treatment.
Figure 5. (a) Time-dependent optical absorption spectra of
K2Cr2O7 solution with an initial CrVI concentration of 21 mgL–1
in the presence of 20 mg of flowerlike BiOBr nanostructure S1; (b)
time-dependent CrVI concentration variation over different BiOBr
nanostructures.
More importantly, the superior removal capacity of the
as-obtained flowerlike BiOBr nanostructure could be real-
ized in a wide pH range. The CrVI removal capacity of the
flowerlike BiOBr nanostructure S1 at various pH values is
illustrated in Figure 6. It was found that CrVI ions could be
effectively removed over a wide pH range from 3 to 11 and
that the removal capacity decreased when the pH value was
below 3 or above 11. It was proposed that the removal ca-
pacity at different pH values was strongly related to the
surface charge of BiOBr as well as the CrVI species present
in solution. The zeta potential of flowerlike BiOBr nano-
structures was estimated to be 30.6 mV in deionized water
(Figure S8, Supporting Information), which illustrated the
existence of positive charge on the BiOBr surface. In the
–
2–
K2Cr2O7 solution, the HCrO4 and CrO4 ions with nega-
tive charge are the dominant species of CrVI in the pH
range of 3 to 11.[43,44] It is believed that the highly efficient
removal of CrVI in the pH value of 3 to 11 is probably due
to the strong coulombic attraction between the positively
charged BiOBr nanostructures and the negatively charged
Figure 4. (a) Nitrogen adsorption–desorption isotherm and (b)
pore size distribution of the flowerlike BiOBr nanostructures ob-
tained in 5 mm CTAB solution (S1).
Adsorption Capacity for CrVI
–
CrVI ions (HCrO4 or CrO42–). The poor adsorption ca-
The time-dependent optical absorption spectra of a pacity at low pH values (Ͻ 3) is mainly owing to the forma-
K2Cr2O7 solution with an initial CrVI concentration of tion of the uncharged H2CrO4 species, which cannot be ad-
21 mgL–1 in the presence of 20 mg of flowerlike BiOBr sorbed efficiently. Large quantities of OH– ions in the high
nanostructure S1 is shown in Figure 5a. With the increase pH value (Ͼ 11) solutions would compete with the CrVI
in the adsorption time, the absorption peak of the K2Cr2O7 species for adsorption sites on the surface of BiOBr, which
solution intensely decreases. The removal efficiency was would result in the decrease in efficiency of CrVI removal.
about 94% after 2 h of adsorption, which was much higher Generally, most reported absorbents reached their maxi-
than that of platelike BiOBr nanostructures (Figure S7, mum adsorptive capacity of heavy metals only at the opti-
Supporting Information). The time-dependent CrVI concen- mal pH value.[40,41,45,46] Hence, we believe that the flower-
tration variation curve over the flowerlike and platelike Bi- like BiOBr nanostructure with its remarkable removal ca-
OBr products is given in Figure 5b. It indicated that the pacity in a wide pH range would be a significant potential
flowerlike BiOBr nanostructure exhibited a very fast ad- absorbent, which could be used in practical water treat-
sorption rate for CrVI ions at the initial stage and that 79% ment.
4
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BiOBr Nanostructures and CrVI Removal Capacity
Table 1. Experimental conditions for the preparation of BiOBr
nanostructures.
Br precursor
C [mm][a]
Temp. [°C]
Time [min]
S1
S2
S3
S4
S5
S6
S7
S8
S9
CTAB
CTAB
CTAB
CTAB
CTAB
KBr
KBr
KBr
CTAB
5
3
8
16
30
3
5
30
5
5
5
110
110
110
110
110
110
110
110
110
110
110
30
30
30
30
30
30
30
30
30
5
10
20
30
30
Figure 6. Effect of pH on the CrVI ions removal in the presence of
20 mg of flowerlike BiOBr nanostructure S1.
S10 CTAB
S11 CTAB
S12 CTAB
S13 CTAB
5
5
60
[a] The concentration of Br source.
Conclusions
In summary, a facile and fast microwave irradiation
method has been developed for the first time to synthesize
Characterizations: X-ray powder diffraction (XRD) was carried out
with a Bruker axs D8 Discover (Cu-Kα = 1.5406 Å) instrument at
well-defined 3D flowerlike BiOBr nanostructures by using a scan rate of 2°min–1 in the 2θ range from 10 to 70°. Scanning
electron microscopy (SEM) and energy dispersive X-ray (EDX)
images were taken with a Hitachi S4800 scanning electron micro-
scope operating at 5.0 kV. TEM and selected-area electron diffrac-
tion (SAED) images were recorded with a Philips Tecnai 20 elec-
tron microscope by using an accelerating voltage of 200 kV. Sam-
ples for TEM analysis were prepared by drying a drop of nanocrys-
tal dispersion in absolute ethanol on carbon-coated copper grids.
The Brunauer–Emmett–Teller (BET) specific surface area of the
powders was analyzed by nitrogen adsorption with a Micromeritics
ASAP 2020 nitrogen adsorption apparatus (USA). All of the as-
CTAB as the bromide source and soft template. In this fab-
rication, CTAB played a crucial role in directing the con-
struction of 3D hierarchical BiOBr nanostructures. A pos-
sible formation process of flowerlike BiOBr nanostructures
in different CTAB concentrations was discussed. The as-
synthesized BiOBr 3D flowerlike nanostructure possessed
a large BET surface area and exhibited excellent removal
capacity and fast adsorption rate for CrVI in a wide pH
range, which demonstrated that it could be used as an ideal
material for the removal of CrVI ions from water. It is also prepared samples were degassed at 100 °C for 4 hours prior to the
nitrogen adsorption measurements. The zeta potential for the prod-
uct was determined with a Malven ZEN3690 zeta potential ana-
lyzer. The pH of the K2Cr2O7 solution was adjusted with 1 m HCl
or 2 m NaOH and measured with a pH meter (Sartorius).
expected to be useful in many other applications, such as
sterilization, degradation of organic pollutants, and so
forth.
Adsorption Experiment of BiOBr Nanostructures: The initial CrVI
solution (21 mgL–1) was prepared by dissolving K2Cr2O7 (60 mg)
in deionized water (1 L) at room temperature. BiOBr powders
(20 mg) were added to the prepared CrVI solution (20 mL) whilst
stirring. At each given time interval, the suspension was sampled
(2 mL) and centrifuged to remove the BiOBr powders. The concen-
tration of K2Cr2O7 during the adsorption was measured with a
Shimadzu UV2800 spectrophotometer. All of the measurements
were carried out at room temperature.
Experimental Section
Chemicals: Bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] was pur-
chased from Tianjin Fuchen Chemical Reagents Factory (China).
Mannitol was purchased from Sinopharm Chemical Reagent Co.,
Ltd. (Shanghai, China). K2Cr2O7, KBr, and cetyltrimethylammo-
nium bromide (CTAB) were purchased from Aladdin (Shanghai,
China). All of the reagents were analytical grade and were used
directly without further purification.
Supporting Information (see footnote on the first page of this arti-
cle): EDX spectrum of S1, XRD patterns of S2 to S8, SEM images
of S5 to S8, S12, and S13, nitrogen adsorption–desorption iso-
therm of S7, time-dependent optical adsorption spectra of
K2Cr2O7 solution in the presence of S7, and zeta potential of S1.
Preparation of BiOBr Nanostructures: In a typical synthesis,
Bi(NO3)3·5H2O (0.485 g, 1 mmol) was dissolved in mannitol
(30 mL, 0.1 m) that contained CTAB (5 mm). The mixture was
stirred and sonicated until all of the chemicals were well dispersed.
The mixture was heated to 110 °C within 3 min and then kept at
that temperature for 27 min in a microwave reactor (XH-300A, Be-
ijing Xianghu Technology Co., Ltd.), irradiation power was 500 W.
After microwave treatment, the mixture was cooled to room tem-
perature. A white precipitate was obtained by centrifugation and
washed with deionized water and ethanol five times. Finally, the
product was dried in a desiccator for a few days for further charac-
terization. Other samples of BiOBr nanostructures were also pre-
pared under identical conditions by changing the Br source, reac-
tion time, and reaction temperature. The detailed experimental pa-
rameters are listed in Table 1.
Acknowledgments
This work was financially supported by the National Natural Sci-
ence Foundation of China (NSFC) (grant number 21171136), the
Program for New Century Excellent Talents in University (NCET-
09–0136), and the Outstanding Youth Scientific Foundation of Hu-
bei Province (2009CDA075).
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Received: December 22, 2011
Published Online: ᭿
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© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: A11427
/KAP1
Date: 03-04-12 15:08:39
Pages: 7
BiOBr Nanostructures and CrVI Removal Capacity
Nanostructures by Microwave
Well-defined 3D flowerlike BiOBr nano-
structures have been successfully synthe-
sized by a facile and fast microwave irradia-
tion method by using cetyltrimethylam-
monium bromide as both the bromide
source and soft template. The as-prepared
flowerlike BiOBr nanostructures possess a
large surface area and exhibit an excellent
removal capacity and fast adsorption rate
for CrVI ions in a wide pH range.
G. Li, F. Qin, H. Yang, Z. Lu, H. Sun,
R. Chen* ........................................... 1–7
Facile Microwave Synthesis of 3D Flower-
like BiOBr Nanostructures and Their Ex-
cellent CrVI Removal Capacity
Keywords: Bismuth oxybromide / Nano-
structures / Templated synthesis / Micro-
wave chemistry / Chromium
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
7