Sonochemical synthesis and characterization of lead iodide hydroxide micro/nanostructures

Article abstract of DOI:10.1016/j.ultsonch.2013.05.007

For the first time, micro/nano-sized lead iodide hydroxide; Pb(OH)I, has been successfully prepared via a simple ultrasonic method. In this method, lead nitrate and lithium iodide were applied as starting reagents to fabricate Pb(OH)I micro/nanostructures

Full text of DOI:10.1016/j.ultsonch.2013.05.007

Accepted Manuscript
Sonochemical Synthesis and Characterization of Lead Iodide Hydroxide Micro/
nanostructures
Farnosh Tavakoli, Masoud Salavati-Niasari, Fatemeh Mohandes
PII:
S1350-4177(13)00115-6
DOI:
http://dx.doi.org/10.1016/j.ultsonch.2013.05.007
ULTSON 2313
Reference:
To appear in:
Ultrasonics Sonochemistry
Received Date:
Revised Date:
Accepted Date:
30 December 2012
15 May 2013
20 May 2013
Please cite this article as: F. Tavakoli, M. Salavati-Niasari, F. Mohandes, Sonochemical Synthesis and
Characterization of Lead Iodide Hydroxide Micro/nanostructures, Ultrasonics Sonochemistry (2013), doi: http://
dx.doi.org/10.1016/j.ultsonch.2013.05.007
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Sonochemical Synthesis and Characterization of Lead Iodide Hydroxide
Micro/nanostructures
Farnosh Tavakolia, Masoud Salavati-Niasari* a, b, Fatemeh Mohandesb
a Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, I. R. Iran
b Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317–51167, I. R. Iran.
* Corresponding author. Tel.: +98 361 5912383; Fax: +98 361 5552935;
E-mail address: salavati@kashanu.ac.ir (M. Salavati-Niasari)
Abstract
For the first time, micro-/nano-sized lead iodide hydroxide; Pb(OH)I, has been successfully prepared via a
simple ultrasonic method. In this method, lead nitrate and lithium iodide were applied as starting reagents to
fabricate Pb(OH)I micro/nanostructures at different conditions. The effect of different surfactants like N,N-
bis(salicylidene)-ethylenediamine (H2salen), sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP),
sonication time, and ultrasonic intensity on the morphology and particle size of the products has been
investigated. The as-produced micro/nanostructures were characterized with the aid of XRD, SEM, TEM,
UV-vis, EDS and FT-IR. According to the SEM images, different morphologies of Pb(OH)I including micro-
and nano-sized rods were formed by changing the preparation conditions. Based on the XRD results, it was
found that Pb(OH)I and PbI2 have been produced with and without sonication at the same conditions,
respectively. The use of the H2salen and sonication treatment were confirmed to be the crucial factors
determining the formation of one-dimensional Pb(OH)I micro/nanostructures.
1

Keywords: Laurionite; Nanostructures; Ultrasonic method; Surfactant.
1. Introduction
Recently, laurionite-type lead halide hydroxide formulated as Pb(OH)X (X = Cl, Br, I) has attracted much
attention because of their some extraordinary structural and spectroscopic features [1]. Laurionite
(PbCl(OH)) is a lead halide mineral. It was first described in 1887 for an occurrence in the Laurium District,
Attica, Greece and named after the town Laurium. It was reported that glasses based on lead halide
hydroxides are used in the conversion of infrared radiation into visible light [2]. Up to now, considerable
efforts have been made on the synthesis of Pb(OH)X nanostructures. Zhang and co-workers have
synthesized lead halides hydroxide tetragonal prismatic tubular crystals in millimeter-scale by a mild ethanol
thermal process [1]. Chen et al. prepared uniform Pb(OH)Cl nanotubes with the aid of a reverse micelles
system [3]. Laurionite nanowires and nanoribbons have been produced by Zhang et al. via a
mechanochemical process [4]. Besides, various morphologies of Pb(OH)X such as needles [5], nanoparticles
[6], microdiskettes [7] nanowires [8], and nano-plates [9] can be achieved by multifarious chemical method.
Ultrasound has become an important tool in synthesis chemistry to generate novel nano-sized materials
under ambient conditions in recent years [10–16]. The ultrasound effects arise from acoustic cavitation,
which is the formation, growth, and implosive collapse of bubbles in a liquid. The growth of the bubble
occurs through the diffusion of solute vapor into the volume of the bubble, while the collapse of the bubble
occurs when the bubble size reaches its maximum value. When solution is exposed to ultrasound irradiation,
the bubbles are implosively collapsed by acoustic fields in the solution. According to hot spot theory, very
high temperatures (>5000 K) are obtained upon the collapse of a bubble. Since this collapse occurs in less
than a nanosecond, very high cooling rates (>1010 K/s) are also obtained [17, 18]. These extreme conditions
2

can drive a variety of chemical reactions to fabricate nano-sized materials. Here, Pb(OH)I
micro/nanostructures were prepared in the presence of ultrasound irradiation. On the other hand, N,N-
bis(salicylidene)-ethylenediamine (H2salen) as a Schiff base compound was synthesized, characterized and
applied as surfactant. Besides the H2salen molecules, the effect of sodium dodecyl sulfate (SDS) and
polyvinylpyrrolidone (PVP) as surfactant on the morphology of the products was investigated.
2. Experimental
2.1. Apparatus and characterization
All the reagents for the synthesis of Pb(OH)I micro/nanostructures such as lead nitrate, lithium iodide,
propylene glycol (PG), methanol, sodium dodecyl sulfate (SDS), polyvinylpyrrolidone (PVP) with
molecular weight of 25000 and 40000, ethylenediamine and salicylaldehyde for the synthesis of N,N-
bis(salicylidene)-ethylenediamine as a Schiff-base compound were commercially available and employed
without further purification. The synthesis was carried out at atmospheric pressure and ambient temperature
with a multiwave ultrasonic generator (Sonicator 3000; Bandeline, MS 72, Germany), equipped with a
converter/transducer and titanium oscillator (horn), 12.5 mm in diameter, operating at 20 kHz. All
experiments were performed with a constant ultrasonic power 0.1 W mL-1, which was measured by
calorimetry.
FT-IR spectra were recorded on Magna-IR, spectrometer 550 Nicolet in KBr pellets in the range of 400–
4000 cm-1. Powder X-ray diffraction (XRD) patterns were collected from a diffractometer of Philips
Company with X’pertpro monochromatized Cu Kα radiation (λ = 1.54 Å). Microscopic morphology of
products was visualized by SEM (Cam Scan, MV2300). TEM images were obtained on a Philips EM208S
transmission electron microscope with an accelerating voltage of 100 kV. The energy dispersive
spectrometry (EDS) analysis was studied by XL30, Philips microscope. Optical properties of the products
3

1
(UV-vis spectrum) were studied on a Perkin-Elmer spectrophotometer. H NMR spectrum of N,Nʹ-
bis(salicylidene)-ethylenediamine, H2salen, was recorded by BRUKER (400 MHz) in CDCl3.
2.2. Synthesis of H2salen
A typical procedure for the synthesis of H2salen as surfactant is as follows: a solution containing 2 mol of
ethylenediamine in 50 mL of methanol was added dropwise into a solution involving 4 mol of
salicylaldehyde. The as-obtained mixture was refluxed under magnetic stirring for 3 h to produce a yellow
precipitate. The yellow H2salen precipitate was filtered and washed with methanol several times, and finally
o
dried at 50 C in vacuum. The formation reaction of the H2salen is shown in Scheme 1. The H2salen ligand
1
1
was analyzed by H NMR and FT-IR spectroscopy. H NMR (400 MHz, CDCl3) data for the H2salen, δ:
13.20 (s, 2H, OH); 8.57 (s, 2H, –CH=N–); 6.85–7.38 (m, 8H, aromatic); 4.00 (s, 4H, –CH2–N=C).
2.3. Synthesis of lead iodide hydroxide micro/nanostructures
Lead iodide hydroxide micro/nanostructures were prepared by reaction between Pb(NO3)2 and LiI with
molar ratio of 1:1 in the presence of ultrasound irradiation. In a typical experiment, an aqueous solution of
LiI (2 mmol) was added dropwise into a solution including 2 mmol of Pb(NO3)2 and 0.5 g of surfactant
during the sonication. In this work, the H2salen, SDS, PVP-25000 and PVP-40000 were used as surfactant at
the same conditions. When the H2salen molecules were applied, propylene glycol was used instead of
distilled water as solvent. The yellowish precipitates obtained under various sonication times were collected
by centrifugation at 4000 rpm for 5 min, washed repeatedly with distilled water and ethanol several times,
o
and dried at 50 C in vacuum for characterization. The preparation conditions for preparing Pb(OH)I
micro/nanostructures have been illustrated in Table 1. During the sonication treatment, reaction temperature
increased. The reaction temperature in different conditions was measured and presented in Table 1. To study
4

the effect of ultrasound irradiation on the morphology and chemical composition of the products, two
o
o
experiments as blank tests were carried out without sonication at room temperature (27 C) and 52 C,
o
respectively. According to Table 1, after sonication for 20 min, the reaction temperature was 52 C.
o
Therefore, the blank tests were carried out with vigorous stirring for 20 min at 27 (sample 10) and 52 C
(sample 11) at the same conditions, respectively. In synthesis of the blank tests, a solution of LiI (2 mmol of
LiI dissolved in 50 mL of distilled water) was added dropwise into a solution containing 2 mmol of
Pb(NO3)2 and 0.5 g of H2salen dissolved in 50 mL of propylene glycol. After stirring for 20 min, deep-
yellow colored precipitates were collected, washed repeatedly with distilled water and ethanol several times,
and dried at 50 oC in vacuum. For the synthesis of the sample 11, the reaction solution was heated at 52 oC.
The as-synthesized products were characterized by FT-IR, SEM, TEM, XRD, UV-vis, and EDS.
3. Results and discussion
Fig. 1 shows FT-IR spectra of the as-synthesized samples in the range of 400–4000 cm-1. FT-IR spectrum
of H2salen is shown in Fig. 1a. The strong peak at 1632 cm-1 is attributed to the v(C=N) as a characteristic
band for the Schiff base compound. The peaks centered at 1575 and 1495 cm-1 are related to the (C=C) of
benzene ring vibrations. The phenolic C–O stretching vibration was appeared at 1282 cm-1 in the IR
spectrum of the H2salen [19]. The symmetric and antisymmetric stretching vibrations of –CH2– are shown at
2927 and 2900 cm-1. All of the distinct absorption peaks of the H2salen Schiff base were corresponding to
the literature [19]. Fig. 1b shows FT-IR spectrum of the Pb(OH)I synthesized by the H2salen after sonication
for 5 min (sample 1). In Fig. 1b, the absorption band centered at 3482 cm-1 and weak peaks at 1630 and 606
cm-1 are attributable to the v(OH) stretching and bending vibrations, respectively, which indicate the
presence of hydroxyl group in the Pb(OH)I micro/nanostructures [20]. In this spectrum, the symmetric and
5

antisymmetric stretching vibrations of CH2 group are shown at 2922 and 2854 cm-1, which indicate the
Pb(OH)I micro/nanostructures were capped by the H2salen molecules.
Optical properties of the as-synthesized Pb(OH)I were investigated for sample 1. UV-vis spectrum of the
Pb(OH)I micro/nanostructures synthesized by the H2salen after sonication for 5 min (sample 1) is shown in
Fig. 2a. As shown in Fig. 2a, there are two absorption peaks centered at 229 nm and 315 nm in the UV-vis
spectrum of Pb(OH)I micro/nanostructures. According to the available reports, two peaks centered at 229
and 315 nm can be attributed to the direct and indirect transitions, respectively [21].
Chemical composition of the Pb(OH)I micro/nanostructures was analyzed by energy dispersive
spectrometry (EDS). In the EDS spectrum of the Pb(OH)I obtained from sample 1 (Fig. 2b), Pb, I and O
elements are detectable. The EDS results gave a rough atomic ratio Pb:I as nearly 1:1, confirming the purity
of the product.
3.1. Influence of sonication time in synthesis of Pb(OH)I
In order to study the effect of sonication time in synthesis of Pb(OH)I, the starting reagents were exposed
to ultrasound irradiation for 5 (sample 1), 10 (sample 2), 15 (sample 3) and 20 min (sample 4). For the
synthesis of the samples 1–4, ultrasonic intensity and amount of the H2salen as surfactant were 60 W/cm2
and 0.5 g, respectively. Typical SEM images on the final products are shown in Fig. 3. SEM images of
Pb(OH)I obtained after sonication for 5, 10, 15, and 20 min were presented in Figs. 3a-d, respectively. Rod-
like micro/nanostructures were obtained by using ultrasound irradiation on the reactant mixture at 60 W/cm2
under different sonication times. Based on the SEM images, we could not determine the length of the rods
exactly. Diameters of the rods synthesized after sonication for 5, 15 and 20 min were several hundred
nanometers. On the other hand, diameter of the rods produced after sonication for 10 min was not very
homogeneous. Based on the SEM image of the product synthesized after sonication for 10 min (Fig. 3b),
6

diameter of the rods was in the range of 80–200 nm. Although the dimensions of the rods increased at high
sonication time, the rods obtained were much uniform. According to the Ostwald ripening growth
mechanism where the larger particles grow at the expense of the smaller particles, dimensions of Pb(OH)I
nanorods increased with increasing sonication time [22].
TEM images of the product synthesized after sonication for 15 min were taken and shown in Fig. 4.
According to Figs. 4a and 4b, Pb(OH)I rod-like microstructures with several micrometers in length and 300–
350 nm in diameter were produced after sonication for 15 min.
In order to confirm the crystal structure and purity of the products, XRD analyses were carried out. XRD
patterns of the products synthesized after sonication for 5, 10, 15, and 20 min are shown in Figs. 5a-d,
respectively. Most of the reflection peaks in Figs. 5a-d can be attributed to the orthorhombic phase Pb(OH)I
with space group of Pnma and cell constants a = 7.8040 Å, b = 4.2000 Å, and c = 10.4510 Å (JCPDS 22-
0655). The sharp reflection peaks in Fig. 5 confirmed high crystallinity of the products.
3.2. Influence of PVP and SDS in synthesis of Pb(OH)I
To examine the role of the polymeric and ionic surfactant on the morphology of the products, Pb(OH)I was
synthesized by polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS) instead of the H2salen after
sonication for 30 min at 60 W/cm2. Figs. 6a and 6b show SEM images of Pb(OH)I synthesized by PVP-
25000 and PVP-40000, respectively. The SEM images in Figs. 6a and 6b indicate formation of very fine
particles. By comparing SEM images of Figs. 6a and 6b, it can be seen that particle sizes of the Pb(OH)I
synthesized by PVP-40000 are smaller than those produced by PVP-25000 due to higher steric hindrance
effect of PVP-40000. SEM image of the Pb(OH)I obtained in the presence of SDS is shown in Fig. 6c.
According to this micrograph, Pb(OH)I disk-like microstructures have been formed with SDS.
7

3.3. Influence of ultrasound intensity in synthesis of Pb(OH)I
The sonication effects were further investigated by changing in sizes of the as-prepared Pb(OH)I under
different ultrasonic intensities by using the H2salen as surfactant. The sonication time in these experiments
was 5 min. The typical ultrasonic intensity was set at 50 and 70 W/cm2. When the starting materials were
under a lower ultrasonic intensity (50 W/cm2), most of the 1-D products were from 300–350 nm in diameter
(Fig. 7a). When ultrasonic intensity was increased to 70 W/cm2, the products showed rod-like morphology
about 90–200 nm in diameter and several micrometers in length (Fig. 7b). By comparing SEM image in Fig.
3a (60 W/cm2) with SEM images in Fig. 7a (50 W/cm2) and Fig. 7b (70 W/cm2), it was found that higher
ultrasonic intensities resulted in the formation of nanorods plus microrods with much shorter diameter and
length. Higher ultrasonic intensity can induce more cavitation bubble collapse and a stronger shock wave,
which can prevent the crystal growth. Therefore, by changing the ultrasonic intensity, we can control the
dimensions of the nanorods.
3.4. Influence of ultrasound irradiation on the morphology and chemical composition of the products
To study the effect of ultrasound irradiation in synthesis of the products, one blank test was carried out
o
without sonication at room temperature (27 C) with vigorous magnetic stirring for 20 min by using
Pb(NO3)2, LiI and H2salen as starting reagents. Product of this blank test was marked as sample 10. SEM
images of the sample 10 are shown in Figs. 8a and 8b. It is interesting that the rods produced in the presence
of ultrasound irradiation disappeared, and micro-sized structures with high agglomeration were formed
under magnetic stirring. In addition, the presence of several hexagon-shaped microdisks is seen in Fig. 8a.
o
Since the reaction temperature increased from room temperature to 52 C after sonication for 20 min, the
o
blank test was repeated at 52 C under magnetic stirring for 20 min by using Pb(NO3)2, LiI and H2salen as
starting reagents. SEM images of sample 11 obtained from this blank test are seen in Figs. 9a and 9b.
8

According to Fig. 9, morphology of the sample 11 is hexagonal microdisks. By comparing SEM images of
o
the samples 10 and 11, it can be seen that by increasing the temperature from 27 to 52 C, quantity of the
hexagonal microdisks increased, and their diameters decreased. Therefore, by increasing the temperature at
the same conditions, morphology of the product shifted to hexagonal disks. It was found that temperature
has a great effect on the morphology of the products. It may be proposed that by increasing the temperature,
energy was continuously added to the reaction system, and this led to self-assembly of the nanocrystals for
the preparation of hexagon-shaped microdisks.
XRD pattern of the blank test synthesized at room temperature is presented in Fig. 10. All the reflections in
Fig. 10 can be readily indexed to the hexagonal phase PbI2 with space group of P-3m1 and cell constants a =
4.5570 Å, b = 4.5570 Å, and c = 6.9790 Å (JCPDS 07-0235). These XRD results indicated that the chemical
composition of the products synthesized without soniction differed from those synthesized with the aid of
ultrasound irradiation.
3.5. Possible sonochemical formation mechanism of Pb(OH)I micro/nanostructures
Ultrasound waves radiate through the solution making millions of micro- and nano-sized bubbles form and
grow in the low-pressure stage, and subsequently collapse violently in the high-pressure stage. The
collapsing bubbles generate microjets and shockwaves that lead to pressures reaching hundreds or thousands
of atmospheres. The energy released from this process, known as acoustic cavitation can accelerate the rate
of chemical reactions [23]. In this work, Pb(OH)I micro/nanostructures have been synthesized by Pb(NO3)2,
LiI and different surfactants in the presence of ultrasound irradiation. The proposed chemical reactions for
the preparation of the Pb(OH)I micro/nanostructures in the presence of ultrasound irradiation was considered
as follows:
9

We can assume that Pb2+ ions in the solution combine with iodide ions to yield PbI+ species. Among the
•
•
•
–
radicals generated in the sonolysis of water molecules under the air atmosphere such as H, OH, O2 and
•
–
•HO2, O2 radicals are known to participate in the synthesis of nano-sized materials especially metal oxide
–
nanostructures [24–26]. After combining the •O2 anionic radicals with the PbI+ cations due to the presence a
•
strong interaction between them, [PbOI]• radicals may form. The [PbOI]• radicals can react with the H
–
radicals to generate Pb(OH)I nuclei. Therefore, it is proposed that the •H and •O2 radicals can participate in
•
the sonochemical synthesis of Pb(OH)I micro/nanostructures. Similar ideas about the participation of the H
–
and •O2 radicals in the synthesis of metal oxides by sonication have been presented by Kumar et al. [27] and
Gutierrez et al. [28].
Based on the SEM images of the products synthesized in different conditions, it is suggested that the
H2salen molecules and ultrasound irradiation have a great effect on the formation and growth of the Pb(OH)I
micro/nanorods. In Scheme 2, the proposed sonochemical formation and growth mechanism of Pb(OH)I
micro/nanorods with the aid of H2salen is schematically seen. This mechanism may be explained as follows.
The Pb(OH)I nanoparticles created at the early stages of the sonochemical reaction adsorb the H2salen
molecules on their surfaces. Then the nanoparticles coated by the H2salen molecules are fused by hydrogen
bonding due to the presence of OH groups in the H2salen molecules. Besides, with the aid of ultrasound
irradiation, the generated bubbles collapse asymmetrically, resulting in the generation of high-speed
microjets [29]. The velocity of these microjets may be very high. The chance of collision between two
H2salen-adsorbed nanoparticles increases due to the very high velocity of the microjets [30, 31]. As a result,
more Pb(OH)I nanoparticles coated by the H2salen molecules fused in an oriented manner, and then rod-like
micro/nanostructures formed.
10

When PVP was applied instead of the H2salen, Pb(OH)I nanoparticles have been formed. As we are aware,
the nanoparticles coated by PVP could not interact with each other by hydrogen bonding due to the absence
of hydroxyl groups in the structure of PVP. Therefore, the as-produced nanoparticles could not fuse in one
direction even in the presence of the microjets produced during the sonication. In fact, 0-D nanostructures
were obtained with the aid of PVP. By using SDS, 2-D microstructures (microdisks) of Pb(OH)I were
prepared. According to the available reports about the synthesis of different nanostructures by SDS, it was
found that sodium dodecyl sulfate molecules can self-aggregate into a series of peculiar structures, such as
cubic, hexagonal, and lamellar in solutions [32, 33]. In this work, we used SDS with lamellar structure to
provide special interlayer spaces to limit the preferential growth and direct arrangement of Pb(OH)I particles
in the two-dimensional direction. As a result, the disk-like microstructures were produced.
4. Conclusion
In this work, N,N-bis(salicylidene)-ethylenediamine (H2salen) was applied as surfactant to produce
Pb(OH)I micro/nanorods with the aid of ultrasound irradiation. Besides the H2salen molecules, PVP and
SDS have been applied as surfactant. Different morphologies of Pb(OH)I were formed by changing the
preparation conditions. Based on the SEM images, it was found that higher ultrasonic intensities resulted in
the formation of nanorods with shorter diameter and length. It was very interested that chemical composition
and morphology of the products synthesized with and without sonication were different. XRD analyses
proved that pure orthorhombic phase Pb(OH)I could be obtained by this method.
Acknowledgement
Authors are grateful to the council of Iran National Science Foundation and University of Kashan for
supporting this work by Grant No (159271/62).
11

References
[1] X. Zhang, Y. Xie, F. Xu, D. Xu, G.E. Zhou, Chem. Lett. 2 (2004) 194–195.
[2] X.-F. Shen, J. Chem. Technol. Biotechnol. 84 (2009) 1811–1817.
[3] Y. Chen, Q.S. Wu, R.H. Yin, Y.P. Ding, J. Nanopart. Res. 9 (2007) 283–287.
[4] H. Zhang, M. Zuo, G.P. Li, S. Tan, S.Y. Zhang, Nanotech. 16 (2005) 3115–3119.
[5] P. Jeevanandam, Y. Koltypin, Y. Mastaib, A. Gedanken, J. Mater. Chem. 10 (2000) 2143–2146.
[6] M.J.S. Fard, A. Morsali, J. Inorg. Organomet. Polym. 20 (2010) 727–732.
[7] G. Wan, G. Wang, Y. Feng, W. Yu, Mater. Res. Bull. 46 (2011) 487–491.
[8] X.F. Shen, J. Chem. Technol. Biotechnol. 84 (2009) 1811–1817.
[9] H. Sadeghzadeh, A. Morsali, V. T. Yilmaz, O. Büyükgüngör, Ultrason. Sonochem. 17 (2010) 592–597.
[10] S.K. Suslik, Ed. Ultrasound: Its Chemical, Physical And Biological Effects; VCH: Weinheim, Germany,
1988.
[11] S. Koda, T. Kimura, T. Kondo, H. Mitome, Ultrason. Sonochem. 10 (2003) 149–156.
[12] M. Salavati-Niasari, J. Javidi, F. Davar, Ultrason. Sonochem. 17 (2010) 870–877.
[13] M. Salavati-Niasari, G. Hosseinzadeh, F. Davar, J. Alloys Compd. 509 (2011) 134–140.
[14] M. Salavati-Niasari, G. Hosseinzadeh, F. Davar, J. Alloys Compd. 509 (2011) 4098–4103.
[15] F. Mohandes, M. Salavati-Niasari, Ultrason. Sonochem. 20 (2013) 354–365.
[16] G. Kianpour, M. Salavati-Niasari, H. Emadi, Ultrason. Sonochem. 20 (2013) 418–424.
[17] K.S. Suslick, S.-B. Choe, A.A. Cichowlas, M.W. Grinstaff, Nature 353 (1991) 414–416.
[18] K. S. Suslick, G. J. Price, J. Annu. Rev. Mater. Sci. 29 (1999) 295–326.
[19] A. Kazemi Babaheydari, M. Salavati-Niasari, A. Khansari, Particuology 10 (2012) 759–764.
[20] E. Esmaeili, M. Salavati-Niasari, F. Mohandes, F. Davar, H. Seyghalkar, Chem. Eng. J. 170 (2011)
278–285.
[21] G. Wan, G. Wang, Y. Feng, W. Yu, Mater. Res. Bull. 46 (2011) 487–491.
12

[22] D. V. Talapin, A. L. Rogach, E. V. Shevchenko, A. Kornowski, M. Haase, H. Weller, J. Am. Chem.
Soc. 124 (2002) 5782–5790.
[23] B. Gates, B. Mayers, A. Grossman, Y.N. Xia, Adv. Mater. 14 (2002) 1749–1752.
[24] H. Destaillats, T. M. Lesko, M. Knowlton, H. Wallace, M. R. Hoffmann, Ind. Eng. Chem. Res., 40
(2001) 3855–3860.
[25] A. M. Chaparro, C. Maffiotte, M. T. Gutiérrez, J. Herrero, Thin Solid Films, 431–432 (2003) 373–377.
[26] S.-H. Jung, E. Oh, K.-H. Lee, Y. Yang, C. G. Park, W. Park, S.-H. Jeong, Crys. Growth Des. 8 (2008)
265–269.
[27] R. V. Kumar, Y. Diamant, A. Gedanken, Chem. Mater. 12 (2000) 2301–2305.
[28] M. Gutierrez, A. Henglein, Ch. H. Fisher, Int. J. Radiat. Biol. 50 (1986) 313–321.
[29] S. J. Doktycz, K. S. Suslick, Science 247 (1990) 1067–1069.
[30] D. Zhang, H. Fu, L. Shi, C. Pan, Q. Li, Y. Chu, W. Yu, Inorg. Chem. 46 (2007) 2446–2451.
[31] J. Geng, W.-H. Hou, Y.-N. Lv, J.-J. Zhu, H.-Y. Chen, Inorg. Chem. 44 (2005) 8503–8509.
[32] L. M. Qi, J. M. Ma, Chem. J. Chin. Univ. 20 (1999) 507–510.
[33] Y. Xie, X. Zheng, X. Jiang, J. Lu, L. Zhu, Inorg. Chem. 41 (2002) 387–392.
13

Figure captions
Fig. 1. FT-IR spectra of (a) H2salen, and (b) the Pb(OH)I microrods synthesized by H2salen after sonication
for 5 min at 60 W/cm2.
Fig. 2. (a) UV-vis spectrum, and (b) EDS pattern of the Pb(OH)I microrods synthesized by H2salen after
sonication for 5 min at 60 W/cm2.
Fig. 3. SEM images of the products synthesized by H2salen at various sonication times (a) 5 min, (b) 10 min,
(c) 15 min, and (d) 20 min at 60 W/cm2.
Fig. 4. (a, b) TEM images of the product synthesized by H2salen after sonication for 15 min.
Fig. 5. XRD patterns of the products synthesized by H2salen at different sonication times (a) 5, (b) 10, (c)
15, and (d) 20 min at 60 W/cm2.
Fig. 6. SEM images of the products synthesized after sonication for 5 min at 60 W/cm2 by different
surfactants (a) PVP-25000, (b) PVP-40000, and (c) SDS.
Fig. 7. SEM images of the products synthesized by H2salen after soniction for 5 min at various ultrasound
intensities (a) 50 and (b) 70 W/cm2.
Fig. 8. SEM images of the product synthesized by H2salen after stirring for 20 min at room temperature (27
oC) without sonication.
o
Fig. 9. SEM images of the product synthesized by H2salen after stirring for 20 min at 52 C without
sonication.
Fig. 10. XRD pattern of the product synthesized by H2salen after stirring for 20 min at room temperature (27
oC) without sonication.
Table 1. Preparation conditions for the synthesis of Pb(OH)I micro/nanostructures.
Scheme 1. Formation reactions of H2salen molecules used as surfactant.
Scheme 2. Proposed sonochemical formation mechanism of the Pb(OH)I micro/nanorods by using H2salen.
14

Fig. 1
15

Fig. 2
16

Fig. 3
17

Fig. 4
18

Fig. 5
19

Fig. 6
20

Fig. 7
21

Fig. 8
22

Fig. 9
23

Fig. 10
24

Table 1
Sample No. Surfactant
Sonication time
Ultrasonic power
Temperature Product
(oC)
Morphology
(min)
5
(W/cm2)
60
1
H2salen
H2salen
H2salen
H2salen
PVP-25000
PVP-40000
SDS
32.4
39.2
45
Pb(OH)I
Pb(OH)I
Pb(OH)I
Pb(OH)I
Pb(OH)I
Pb(OH)I
Pb(OH)I
Pb(OH)I
Pb(OH)I
PbI2
Rod-like shapes
Rod-like shapes
Rod-like shapes
Rod-like shapes
Nanoparticles
2
10
15
20
5
60
3
60
4
60
52.2
31.5
31.8
32
5
60
6
5
60
Nanoparticles
7
5
60
Disk-like shapes
Rod-like shapes
Rod-like shapes
Agglomerated microstructures
Hexagonal plates
8
H2salen
H2salen
H2salen
H2salen
5
50
31.5
34
9
5
70
10*
11*
–
–
27
–
–
52
PbI2
*Blank tests at different temperatures.
25

Scheme 1
26

Scheme 2
27

Research highlights




For the first time, Pb(OH)I nanostructures were produced via a simple sonochemical route.
N,N-bis(salicylidene)-ethylenediamine (H2salen) was synthesized and applied as surfactant.
Different morphologies of Pb(OH)I including nanorods, nanoparticles and nanodisks were formed.
XRD analyses proved that pure orthorhombic phase Pb(OH)I could be obtained by this method.