Simple preparation of chitosan-coated thallium lead iodide nanostructures as a new visible-light photocatalyst in decolorization of organic contamination

Article abstract of DOI:10.1016/j.molliq.2021.117299

Recently, semiconductor photocatalysts have gained significant awareness owing to their high potential for environmental protection and remediation. Suppression of charge carrier recombination and the effective harvesting of solar power are two main aspects of photocatalysis. Fabrication of nanostructured photocatalysts is an encouraging approach to enhance photocatalytic ability. In this research, Tl₄PbI₆ and chitosan-coated Tl₄PbI₆ nanostructures were fabricated via a simple coprecipitation method. The effect of stoichiometric ratio (TlI to PbI₂), variety of surfactants, and Tl₄PbI₆ content was scrutinized on the shape and structure of products. The bandgap of Tl₄PbI₆ was estimated at 2.6 eV, which made it suitable for photocatalytic activity. The morphology of products was carried out by FESEM photographs, indicating that various parameters had a significant impact on the size and morphology of the products. This demonstrates the first investigation of the photocatalytic ability of Tl₄PbI₆ and chitosan-coated Tl₄PbI₆ nanostructures. The photocatalytic activity was considered to destruct several dyes such as thymol blue, rhodamine B, methyl orange, and methyl violet under visible light. The outcome showed that chitosan-coated Tl₄PbI₆ can eliminate thymol blue with high efficiency (76.3%). Based on reusability, chitosan-coated Tl₄PbI₆ is so durable and maintains its great photocatalytic performance across five reaction cycles. Indeed during the fifth period, the reduction in photocatalytic activity is 7.7%.

Full text of DOI:10.1016/j.molliq.2021.117299

Journal of Molecular Liquids 341 (2021) 117299
Contents lists available at ScienceDirect
Journal of Molecular Liquids
journal homepage: www.elsevier.com/locate/molliq
Simple preparation of chitosan-coated thallium lead iodide
nanostructures as a new visible-light photocatalyst in decolorization of
organic contamination
a
a
b
a
a
Elahe Rahimzade , Mojgan Ghanbari , Hassan Abbas Alshamsi , Maryam Karami , Mahin Baladi ,
a,
⇑
Masoud Salavati-Niasari
a
Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran
Department of Chemistry, College of Education, University of Al-Qadisiyah, Diwaniya 1753, Iraq
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 22 May 2021
Revised 17 July 2021
Accepted 15 August 2021
Available online 30 August 2021
Recently, semiconductor photocatalysts have gained significant awareness owing to their high potential
for environmental protection and remediation. Suppression of charge carrier recombination and the
effective harvesting of solar power are two main aspects of photocatalysis. Fabrication of nanostructured
photocatalysts is an encouraging approach to enhance photocatalytic ability. In this research, Tl
chitosan-coated Tl PbI nanostructures were fabricated via a simple coprecipitation method. The effect of
stoichiometric ratio (TlI to PbI ), variety of surfactants, and Tl PbI content was scrutinized on the shape
and structure of products. The bandgap of Tl PbI was estimated at 2.6 eV, which made it suitable for
4 6
PbI and
4
6
2
4
6
Keywords:
4
6
Photodegradation
Water purification
Organic dyes
photocatalytic activity. The morphology of products was carried out by FESEM photographs, indicating
that various parameters had a significant impact on the size and morphology of the products. This
demonstrates the first investigation of the photocatalytic ability of Tl PbI and chitosan-coated Tl PbI
4 6 4 6
Ternary halide semiconductors
Tl
4
PbI
6
nanostructures. The photocatalytic activity was considered to destruct several dyes such as thymol blue,
rhodamine B, methyl orange, and methyl violet under visible light. The outcome showed that chitosan-
coated Tl
coated Tl
4
PbI
6
can eliminate thymol blue with high efficiency (76.3%). Based on reusability, chitosan-
6
is so durable and maintains its great photocatalytic performance across five reaction
4
PbI
cycles. Indeed during the fifth period, the reduction in photocatalytic activity is 7.7%.
Ó 2021 Elsevier B.V. All rights reserved.
1
. Introduction
lem, semiconductor photocatalysis has been recognized as a sus-
tainable, low cost, and eco-friendly procedure using solar energy
[6,7]. Until now, the investigation has been concentrated on tita-
Clean water is one of the basic elements for the continuation of
any kind of life. The earth is encircled with 70% water, neverthe-
less, just 2.5% is accessible for domestic and manufacturing utiliza-
tion, agriculture, drinking [1]. In the 21st century, remediation and
protection of the environment are the biggest challenges for
humanity because of the depleted water supplies, rapid industrial
developments, global warming, uncontrolled groundwater devel-
opment, and environmental contamination making strange climate
changes [2,3]. Several industrial divisions, including textiles, print-
ing, and dyeing industries release massive amounts of artificial
organic colorants as sewages [4,5]. Between them, textile manufac-
turers release yearly 15% (1000 tons) of nonbiodegradable col-
orants as sewage. Hence, removing these pollutants from sewage
is very important to preserve the environment. To solve this prob-
nium dioxide (TiO
photostability, non-toxicity, and excellent photocatalytic activity.
However, TiO is just sensible to ultraviolet radiation and uses just
4% of the accessible sunlight, which greatly limits its potential use.
Therefore, there is requirement to promote innovative
approaches to enhance the use of solar power [7]. Scientists have
dedicated significant consideration to the construction of visible-
light-driven photocatalysts for the sewage purification process.
Today, over 150 semiconductor substances are accessible for eco-
logical treatment purposes, which comprise carbides, sulfides,
metal oxides, hydroxides oxyhalides, chalcogenides, and halides
[8–13].
2
) for energy and ecological uses due to its high
2
a
One of the main challenges in the scientific community is the
preparation of new nanomaterials with distinctive structures and
electronic/optoelectronic features. Researchers have tended to
the single crystalline wide bandgap semiconductors for a long
⇑
Corresponding author.
E-mail address: Salavati@kashanu.ac.ir (M. Salavati-Niasari).
https://doi.org/10.1016/j.molliq.2021.117299
167-7322/Ó 2021 Elsevier B.V. All rights reserved.
0

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
4 6
Scheme 1. Schematic diagram of the fabrication of Tl PbI nanoparticles and the effect of capping agents on the particle size and morphology.
4 6
Scheme 2. Schematic diagram of the mechanism for the photocatalytic degradation chitosan-coated Tl PbI nanostructures over organic dyes as pollutant.
2

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
Table 1
Different condition for preparation of Tl
4
PbI
6
.
Sample no.
TlI: PbI
2
molar ratio
Type of capping agent
Products
Grain Size (nm)
1
2
3
4
5
6
7
8
9
4:1
2:1
2:1
2:1
2:1
2:1
2:1
2:1
2:1
2:1
–
–
–
–
Tl
Tl
Tl
Tl
Tl
Tl
4
4
4
4
4
4
PbI
PbI
PbI
PbI
PbI
PbI
6
6
6
6
6
6
38.7
37.1
37.2
39.2
34.1
40.3
–
–
–
SDS
NaHSal
EDTA
,TlI
, TlI
, TlI
, TlI
HTAB
PVP-25000
PVP-25000
PVP-25000
PVP-25000
Chitosan-coated Tl
Chitosan-coated Tl
Chitosan-coated Tl
4
PbI
4
PbI
4
PbI
6
6
6
(0.05 g)
(0.07 g)
(0.1 g)
1
0
Fig. 1. XRD pattern of samples a) 2, b) 3, c) 4, d) 5, e) 6, and f) 7.
time. Semiconductors with high mass density are utilized in vari-
ous fields, for instance, medical imaging, homeland security, and
nuclear materials [14–17]. Currently, nanostructured semiconduc-
tors have attracted great concentration owing to their special phys-
ical and chemical characteristics for a wide range of notable
application such as photocatalysts [18,19], sensors,[20,21],
lithium-ion batteries [22] and optoelectronic devices [23,24].
Lately, ternary halide semiconductors with the general formula
venient way, and has various advantages such as eco-friendly, low
cost, high uniformity of nanomaterials, and a simple modification
of component [25,26]. We utilized Tl
of organic dyes. Since, Thallium and Lead are toxic, we coated it
with chitosan to eliminate toxicity of Tl PbI . On the other hand,
4 6
PbI for photodegradation
4
6
this compound is applied as a catalyst and eventually comes out
of the solution in solid form. Chitosan is the second most abundant
after cellulose, derived as a deacetylated version of chitin, a natu-
rally occurring amino polysaccharide. Its biodegradable, biocom-
patible, non-toxic, and antibacterial properties have directed
notable study in pharmaceutical and biomedical applications,
including wound-healing dressing, tissue engineering, drug deliv-
ery, etc [27].
of M
I) have drawn great attention in the scientific investigations [11].
In this work, we fabricated Tl PbI nanostructures using co-
4 6
NX (M = In, Tl, N = Pb, Hg, Ge, Zn, Cd, Mg, and X = Cl, Br,
4
6
precipitation method. Co-precipitation is an economical method
to synthesize nanomaterial as it offers an effortless, clean and con-
3

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
Fig. 2. SEM images of the samples a) 1, b) 2, c) 3, d) 4, e) 5, f) 6, g) 7, h) 8, i) 9, j) 10 and k) size distribution diagram of samples 8–10.
2
. Materials and methods
2.3. Photocatalytic performance
2.1. Materials
4 6
The photocatalytic activity of Tl PbI and its chitosan-coated
was examined by its potential for degradation of different organic
colorants below visible radiation. An Osram light (150 W) was
employed as the radiation source, containing a wavelength in the
range of 400–780 nm for the photocatalytic process. The experi-
ments were conducted without catalyst and light, and almost no
dye was destroyed after 120 min. 100 mg catalyst was added to
100 mL 10 ppm of organic dye solutions for every experiment.
The suspension was mixed in the dark for 0.5 h before turning
on the visible light. A 5 mL specimen is removed from the suspen-
sion every 15 min during irradiation and centrifuged at 12,000 rpm
for 3 min. The buoyant was collected, separated, and observed with
a UV–Vis spectrophotometer.
Lithium iodide 99% purity (LiIꢀ2H
2
O), Lead (II) nitrate 99.999%
purity (Pb(NO ) ), Chitosan, high purity (low molecular weight),
3 2
Thallium (I) nitrate 99.5% purity (TlNO
monium bromide 95% purity (HTAB), Sodium dodecyl sulfate
SDS) (purity ꢁ 90 %), acetic acid 100% purity, Ethylenediaminete-
traacetic acid 99% purity (EDTA), Polyvinylpyrrolidone 99.5% purity
PVP-25000), Sodium salicylate 99.9% purity (NaHSal), were pur-
chased from Merck Company and applied without purification
see Schemes 1 and 2).
3
), Hexadecyltrimethylam-
(
(
(
4 6
2.2. Preparation of Chitosan-coated Tl PbI nanostructure
2.4. Physical instruments
The Thallium iodide (TlI) was prepared by adding TlNO
tion to LiI solution through a facile co-precipitation method. Lead
iodide (PbI ) was similarly prepared by adding the solution of Pb
NO to LiI. The TlI mixture was added to SnI and stirred for
5 min. The yellowish precipitate was filtered, washed with water
three times and dried at 65 °C. 1.0 g chitosan was dissolved in
0 mL acetic acid 1%. Mg Tl PbI (M = 0.05, 0.07, and 0.1 g) was
added to 20 mL chitosan solution. The suspension was stirred for
h. The product was dried at 50 °C over night. Table 1 demon-
strates various fabrication condition to obtain Tl PbI and
chitosan-coated Tl PbI
3
solu-
An X-ray diffractogram (Philips) with X’ Pert Pro sieved by cop-
per K radiation (k = 15.4 nm) was used to record the XRD patterns.
a
2
(
1
3
)
2
2
The X’Pert HighScore Plus software was applied to distinguish the
compounds. The morphology of the samples was obtained by TES-
CAN BRNO-Mira3 LMU field emission scanning electron micro-
scopy. The samples were covered by a thin layer of gold (Au),
before taking images for achieving better contrast and bypassing
charge accretion. The energy-dispersive spectroscopy (EDS) equip-
ment by 20 kV exciting charge was utilized for the element analy-
sis of the products. The surface areas (BET) were characterized via
6
4
6
1
4
6
4
6
.
4

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
Fig. 3. EDS spectrum of the samples a) 1, b) 2, c) 3, d) 4, e) 5, f) 6, and g) 7.
nitrogen adsorption at ꢂ196 °C employing an automated gas
adsorption analysis equipment (Tristar 3000, Micromeritics). The
UV–Visible spectrum was registered to utilize a JASCO UV–Vis
scanning spectroscopy (V-670). The GC-2550TG (Teif Gostar Faraz
Company, Iran) was utilized toward each alchemic agent. The FT-IR
4 6
the purity of products. Pure Tl PbI was only composed in the pres-
ence of PVP-25000. There are a significant amount of TlI 00–006-
0279 with orthorhombic structure as by-product in the presence
of other surfactants. Therefore, the desired condition was selected
in the presence of PVP-25000 as a polymeric surfactant for further
experiments. Scherrer formula was applied to estimate the grain
size; D = Kk/bcosh (1) [28] to be between 34 and 40 nm (Table 1).
The shape, morphology, uniformity, and particle size of prod-
ucts were carried out through the FESEM micrographs (Fig. 2).
Fig. 2a and b show the effect of molar ratio on morphology.
spectra of the samples were documented by a Shimadzu Varian
ꢂ1
4
300 spectrometer between 400 and 4000 cm in KBr pellets.
Transmission electron microscopy (TEM) was executed by utilizing
JEM-2010 UHR JEOL transmission electron microscope (UHR-TEM)
for the first batch, FEI Tecnai G2 F20 for the second batch, and
Thermo Fischer Talos F200x for the last batch of the pictures.
Microstructures were composed when the molar ratio of TlI: PbI
was 4:1. mm rods were created by reducing the molar ratio to
:1. Fig. 2(c-g) show the effect of different type of surfactants on
2
2
3
. Result and discussion
shape and size of particles. In the presence of SDS, nanorods with
an average diameter of 98 nm are formed (Fig. 2d). Bulk structures
are created in the presences of NaHSal, EDTA, and HTAB. As can be
seen, the uniform nanoparticles were only composed in the pres-
ence of PVP-25000 (Fig. 2g). So, the desired condition was chosen
in the presence of PVP-25000 as a polymeric surfactant for further
3.1. Characterization
The XRD patterns of as-prepared products are illustrated in
Fig. 1. Sample 2 was formed from Thallium Lead Iodide 00–033-
774 with Orthorhombic structure (Fig. 1a). Fig. 1(b-f) displays
the influence of different surface-active agents (surfactants) on
0
experiment. Fig. 2(h-j) indicates chitosan-coated Tl
4 6
PbI with dif-
ferent content of Tl PbI . A uniform morphology and finer particles
4
6
5

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
Fig. 4. TEM images of sample 10.
were formed when the particles were coated with chitosan. Fig. 2k
displays the histogram size distribution of samples 8–10 obtained
using Digimizer software, indicating that most particles of sample
is 2.2 nm. From the BJH plot, the pore volume average and pore
diameters are 0.004 cm g and 1.2 nm, respectively (Fig. 5b). This
data is confirmed by SEM and TEM outcomes.
3
ꢂ1
8
are between 20 and 40 nm. Most particles of samples 9 and 10
The optical properties of sample 7 was carried out using diffuse
are between 40 and 60 nm.
4 6
reflection spectroscopy (DRS). Fig. 6 shows that Tl PbI nanostruc-
One of the analytical techniques utilized for the chemical char-
acterization or elemental analysis of a sample is Energy-dispersive
X-ray spectroscopy (EDX). Fig. 3 demonstrates the EDX spectra of
tures have normal absorptions in the range of 210–510 nm. The
following equation as used to determine the optical bandgap (B.
1
/n
G.) of Tl [11]: (
4
PbI
6
aht
)
= b(ht-B.G.) (2); where a is absorption
Tl
4 6
PbI , indicating all peaks are attributed to I, Tl, and Pb elements.
coefficient, ht is photon energy, b is a constant called the band tail-
Consequently, the products are perfectly purified and related to the
XRD results. Besides, the uniform distribution of elements in the
samples was confirmed by the EDX result.
ing parameter, B.G. is the energy of the optical bandgap, and n is
the power factor of the transition mode that is 2 or 1/2 for indirect
and direct allowed transitions [11]. By plotting the graph between
2
Fig. 4 indicates the TEM photographs of chitosan-coated Tl
4
PbI
6
(aht)
versus photon energy (ht); Extrapolating the straight line
nanostructures (sample 10) in three scales 100, 40, and 20 nm. The
uniform nanoparticles are observed in this figure, which corre-
sponds to the SEM and XRD outcomes.
To calculate the specific surface area and pore volume of sam-
ples, the BET surface area analysis is a standard tool [29,30]. The
portion of the curves to zero absorption coefficient value gives
the energy band gap value. The bandgap of Tl PbI was determined
4
6
2.6 eV making it suitable for photocatalytic activity in the visible
region.
N
2
adsorption/desorption isotherm for sample 10 is illustrated in
3.2. Photocatalytic ability
Fig. 5a. As reported by IUPAC classification, sample 7 exhibits the
isotherm type III with H3-type hysteresis loop (Fig. 5a), which is
referred to as microporous materials. The specific BET surface area
4 6 4 6
The photocatalytic ability of Tl PbI and chitosan-coated Tl PbI
nanostructures was analyzed by observing the decolorization of
cationic and anionic organic dyes, such as Methyl Violet (MV),
2
ꢂ1
was determined to be 41.2 m g , and the average pore diameter
6

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
2
Fig. 5. (a) Low temperature N adsorption/desorption isotherm, (b) BET plot, and (c) BJH plot of sample 10.
after decolorization, separately [31]. The impact of diverse dyes on
different samples was conducted to gain better performance.
Fig. 7a exhibits the photocatalytic degradation sample 7 in the
presence of ThB, RhB, MO, and MV. The dye destruction percent-
ages of mentioned dyes are about 72.4%, 47.8%, 60.2%, and 48.5%
after 120 min, respectively. As can be seen in Fig. 7c, e, and g,
increasing the Tl
pounds enhances the photocatalytic efficiency. The results show
that chitosan inhibits the photocatalytic activity of Tl PbI because
it occupies the active surface of the catalyst. However, enhancing
the Tl PbI content increase the surface of catalyst and enhances
the dye adsorption on the chitosan-coated Tl PbI [32]. Fig. 7g
4 6 4 6
PbI content in chitosan-coated Tl PbI com-
4
6
4
6
4
6
shows that sample 10 can degrade 50.0% of thymol blue. Moreover,
the possible reaction rate constants of organic colorants were
determined depending on the Langmuir–Hinshelwood mechanism
Fig. 6. DRS spectrum and optical density (ahm
)2 vs. energy (E) plot of the sample 7.
[
0 0
28]. ln(C /C) = kt (4); Where C is the initial concentration of
organic dyes; C is the concentration of organic pollutants at t time;
ꢂ1
and k is the Pseudo-first order rate constant (min ). The Pseudo
0
rate constant (k) has been determined from ln(C /C) linear correla-
Methyl Orange (MO), Rhodamine B (RhB), and Thymol Blue (ThB)
in an aqueous solvent, below visible light (Fig. 7). The degradation
tions vs. reaction time. As seen in Fig. 7b, d, f, and h, the greater
photocatalytic proficiency was achieved in a bigger reaction rate
constant. Fig. 8a shows the photoctalytic ability of 0.07 g sample
percentage (%D) was defined as follows: %D = (C
0
-C
t
)/C
0
ꢃ 100 (3);
Where C and C are the solution absorbance of sample before and
0
t
7

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
Fig. 7. Photocatalytic degradation of different dyes and Plots of ln(C
0
/C) vs time over 0.05 g of different samples (a and b) sample 7, (c and d) sample 8, (e and f) sample 9, and
(
g and h) sample 10 under visible-light irradiation.
1
0, which reveals that increasing catalyst dosage to 0.07 g has
3.2.1. Scavenger- quenching effect
enhanced the degradation percentage to 76.3% and 46.7% for ThB
and MO, respectively. Increasing the catalyst dosage led to an
extensive surface area of the catalyst and increases the absorption
Evaluation of the effect of active species on the degradation of
dyes was carried out by a group of quenchers to scavenge the
active species. The scavengers applied in this research involved
+
of organic dyes on chitosan-coated Tl
33]. Table 2 compared the photodegradation of different iodide
compounds under visible and UV light. As demonstrated in this
table, Tl PbI and chitosan-coated Tl PbI can compete with other
4
PbI
6
surface (sample 10)
Ethylenediaminetetraacetic acid (EDTA) for h , 1,4-Benzoquinone
ꢂ
[
(BQ) for O
2
ꢄ , and benzoic acid (BA) for ꢄOH [34–36]. As exhibited
in Fig. 8a, the destruction performance was insignificantly dimin-
4
6
4
6
ished in the presence of EDTA and BA in comparison with no scav-
ꢂ
iodide compounds as a photocatalyst. We can nominate these com-
pounds as a novel catalyst for the water purification process.
enger. When BQ was used as the O
2
ꢄ
scavenger, an apparent
decrease in photocatalytic efficiency was recognized. Concisely,
8

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
Fig. 8. Photocatalytic degradation of (a) ThB and MO with 0.07 g of sample 10, (b) sample 10 for decolorization of ThB in the presence of BQ, BA, and EDTA as scavenger (c)
cycling runs in the photocatalytic degradation of ThB in the presence of sample 10 under visible irradiation.
Table 2
The photocatalytic activity of different iodide compounds
Sample
Tl PbI
Chitosan-coated Tl
TlCdI nanostructures
nanostructures
nanostructures
nanostructures
Highest decolorization (%)
Lowest decolorization (%)
Catalyst dosage (g)
Source of light
Ref.
4
6
72.6 (ThB)
76.3 (ThB)
94.6 (MB*)
47.8 (RhB)
–
0.05
0.07
0.05
0.05
0.07
0.07
0.05
0.05
0.05
0.05
Vis
Vis
UV
UV
UV
Vis
UV
UV
UV
UV
This work
This work
[10]
[11]
[26]
[32]
[12]
[42]
[43]
PbI
4 6
3
27.0 (MO)
49.1 (MB)
48.9 (ThB)
33.0 (AB1)
57.1 (AB1)
–
Tl
Tl
4
Cdl
HgI
6
85.7 (AB1**
76.9 (RhB)
81.7 (MV)
95.3 (RhB)
89.3 (MO)
66.0 (MB)
54.2 (MO)
)
4
6
CsPbl
3
Ag
2
Ag
2
Cu
2
Cu
2
CdI
4
nanostructures
/AgI nanocomposites
/CuI nanocomposites
/ZnO nanocomposites
ZnI
CdI
4
4
29.1 (MO)
–
ZnI
4
[44]
*
*
Methylene Blue.
Acid Black 1.
*
ꢂ
the impacts of diverse scavengers exposed that ꢄO
2
did the impor-
Chitosan-coated Tl
4
PbI
6
+ h
m
(Visible) !
+
tant role, and OHꢄ or h represented an irrelevant role in the degra-
ꢂ
þ
Chitosan ꢂ coatedTl
4
PbI
6
ðeCB
þ hVB Þ
dation of ThB.
þ
þ
Tl
4
PbI
6
(hVB ) + H
2
O ! Chitosan-coated Tl
4
PbI
6
+ H + OHꢄ
3.2.2. Photocatalytic mechanism
It is completely confirmed that conduction band (CB) electrons
e ) and valence band (VB) holes (h ) are created when aqueous
catalyst suspension is lighted by light energy higher than its band-
gap (2.6 eV) [37]. The photoinduced electrons can reduce the col-
þ
) + OHꢂ
Tl
4
4
PbI
6
6
(hVB
! Chitosan-coated Tl
4
PbI
6
+ OHꢄ
-
+
(
CBꢂ) + O
2
4
6
2
ꢂ
Tl
PbI
(e
! Chitosan-coated Tl
PbI
+ O
ꢄ
orant or react with electron acceptors, for example, O
in water or adsorbed on the catalyst surface, reducing it to O
2
dissolved
þ
ꢂ
ꢂ
H
+ O
2
ꢄ
! HO ꢄ
2
2
ꢄ
(
radical of superoxide anion). The photoinduced holes can react
ꢂ
! ꢄO2ꢂ
ꢂ
O2 + e
with H
2
O or OH oxidizing them into OHꢄ radicals or oxidize the
+
organic dyes to produce R . They have been reported to be respon-
sible for the photodegradation of organic dyes together with other
high oxidant species (peroxide radicals). Therefore, the corre-
sponding reactions at the surface of the catalyst causing the dye
degradation can be represented as follows [26,38–41].
þ
O ! ꢄOH + Hþ
h
+ H
2
ꢄO2ꢂ + eꢂ+ H ! HOOꢄ
þ
9

E. Rahimzade, M. Ghanbari, Hassan Abbas Alshamsi et al.
Journal of Molecular Liquids 341 (2021) 117299
HOOꢄ + H
2
O ! ꢄOH + H
2
O
2
Acknowledgement
þ
+ ꢄO2ꢂ ! H
2
H
2
O
2
The authors acknowledge the University of Kashan by Grant No
159271/ER1) and Iran National Science Foundation (INSF,
97017837) for supporting this investigation.
(
+ eꢂ
! ꢄOH + OH
! ꢄOH
ꢂ
H
2
O
2
OHꢂ + h
þ
References
[
1] C. Santhosh, V. Velmurugan, G. Jacob, S.K. Jeong, A.N. Grace, A. Bhatnagar,
Chem. Eng. J. 306 (2016) 1116.
2] S.-Y. Lee, S.-J. Park, J. Ind. Eng. Chem. 19 (2013) 1761.
3] W. Zhang, M. Wang, W. Zhao, B. Wang, Dalton Trans. 42 (2013) 15464.
4] A. Malathi, P. Arunachalam, J. Madhavan, A.M. Al-Mayouf, M.A. Ghanem,
Colloids Surf., A 537 (2018) 435.
H
2
O + h ! ꢄOH + Hþ
þ
[
[
[
OHꢄ + Dye ! degradation products (e.g., H
2 2
O,CO )
eCBꢂ
[5] A. Malathi, J. Madhavan, J. Nano Res., Trans Tech Publ (2017) 49–61.
6] M. Mao, F. Chen, C. Zheng, J. Ning, Y. Zhong, Y. Hu, J. Alloy. Compd. 688 (2016)
080.
[7] A. Malathi, J. Madhavan, M. Ashokkumar, P. Arunachalam, Appl. Catal. A 555
2018) 47.
+ Dye ! reduction products
[
1
þ
h
VB + Dye ! oxidation products
(
[
8] A. Malathi, V. Vasanthakumar, P. Arunachalam, J. Madhavan, M.A. Ghanem, J.
Colloid Interface Sci. 506 (2017) 553.
3
.2.3. Recyclability of chitosan-coated Tl
For checking the recyclability of chitosan-coated Tl
4 6
PbI
[
9] M. Baladi, M. Ghanbari, M. Valian, M. Salavati-Niasari, Environ. Sci. Pollut. Res.
(2020) 1.
4 6
PbI (sam-
ple 10), the catalyst was centrifuged, washed with ethanol and
water, dried at 70 °C for 24 h, and reused five times under the equal
situations. As shown in Fig. 8b, chitosan-coated Tl PbI is so stable
4 6
[10] M. Ghanbari, F. Ansari, M. Salavati-Niasari, Inorg. Chim. Acta 455 (2017) 88.
[
[
11] M. Ghanbari, M. Salavati-Niasari, Inorg. Chem. 57 (2018) 11443.
12] M. Ghanbari, S. Gholamrezaei, M. Salavati-Niasari, A. Abbasi, J. Mater. Sci.:
Mater. Electron. 28 (2017) 6272.
and maintains its great photocatalytic performance across five
reaction cycles. Indeed during the fifth period, the reduction in
photocatalytic activity is 7.7%.
[13] G.-L. Tan, D. Tang, D. Dastan, A. Jafari, Z. Shi, Q.-Q. Chu, J.P. Silva, X.-T. Yin,
Ceram. Int. 47 (2021) 17153.
[
14] R. Pani, R. Pellegrini, M. Cinti, P. Bennati, M. Betti, F. Vittorini, M. Mattioli, G.
Trotta, V.O. Cencelli, R. Scafe, Nucl. Instrum. Methods Phys. Res. Sect. A:
Accelerat. Spectrom., Detect. Assoc. Equipm. 572 (2007) 268.
[
[
[
15] H. Zandbergen, Acta Crystallogr. Section B: Struct. Crystallogr. Cryst. Chem. 35
4
. Conclusions
(
1979) 2852.
16] L. Tao, J. Huang, D. Dastan, T. Wang, J. Li, X. Yin, Q. Wang, Appl. Surf. Sci. 530
2020) 147265.
17] N. Haghnegahdar, M.A. Tarighat, D. Dastan, J. Mater. Sci.: Mater. Electron. 32
2021) 5602.
(
The Photocatalysis treatment process is one of the encouraging
technology for removing numerous organic pollutants and dyes
from nature due to its low cost, low energy utilization, and supe-
(
[18] B. Jia, W. Jia, F. Qu, X. Wu, RSC Adv. 3 (2013) 12140.
rior catalytic activity. Tl
a low cost, fast, and simple coprecipitation method. Various states
such as types of surfactants, molar ratio, and Tl PbI content have
influenced the morphology, shape, particle size, purity, and struc-
ture. DRS confirmed the bandgap of Tl PbI around 2.6 eV, which
makes it proper for photocatalytic application. Chitosan-coated
Tl PbI degraded thymol blue about 76.3% after 120 min. This
result confirmed that Tl PbI alone or in combination with chitosan
4
PbI
6
nanostructures were synthesized by
[19] Z. Yu, X. Wu, J. Wang, W. Jia, G. Zhu, F. Qu, Dalton Trans. 42 (2013) 4633.
[
20] Y. Jia, L. He, Z. Guo, X. Chen, F. Meng, T. Luo, M. Li, J. Liu, J. Phys. Chem. C 113
2009) 9581.
21] M. Chen, Z. Wang, D. Han, F. Gu, G. Guo, J. Phys. Chem. C 115 (2011) 12763.
(
4
6
[
[22] Y.-S. Lin, J.-G. Duh, M.-H. Hung, J. Phys. Chem. C 114 (2010) 13136.
[23] S. Xing, R. Han, Z. Ma, Y. Wu, Z. Zhou, CrystEngComm 13 (2011) 6033.
[24] M. Fang, X. Tan, B. Cheng, L. Zhang, J. Mater. Chem. 19 (2009) 1320.
[25] M. Ghanbari, F. Soofivand, M. Salavati-Niasari, J. Mol. Liq. 223 (2016) 21.
4
6
4
6
[26] M. Karami, M. Ghanbari, H.A. Alshamsi, S. Rashki, M. Salavati-Niasari, Inorg.
Chem. Front. (2021).
4
6
[
27] A. Ali, S. Ahmed, Int. J. Biol. Macromol. 109 (2018) 273.
is a stable photocatalyst after five runs in the visible region for
future water purification. Besides, the outcomes of photocatalytic
performance revealed that the photocatalytic efficiency was
[
28] M. Ghanbari, M. Salavati-Niasari, Ecotoxicol. Environ. Saf. 208 (2021) 111712.
[29] L. Tao, J. Huang, D. Dastan, T. Wang, J. Li, X. Yin, Q. Wang, Appl. Surf. Sci. 540
2021) 148320.
(
[
30] X.-T. Yin, S.-S. Wu, D. Dastan, S. Nie, Y. Liu, Z.-G. Li, Y.-W. Zhou, J. Li, A. Faik, K.
Shan, Surf. Interfaces 25 (2021) 101190.
enhanced by increasing Tl
scavenger experiments, O
degradation of ThB.
4
PbI
6
content. According to the radical
performed the main role in the
ꢂ
2
ꢄ
[31] Y. Orooji, M. Ghanbari, O. Amiri, M. Salavati-Niasari, J. Hazard. Mater. 389
(2020) 122079.
[
32] M. Karami, M. Ghanbari, O. Amiri, M. Salavati-Niasari, Sep. Purif. Technol. 253
2020) 117526.
[33] S. Sunayana, C. Nitin, R. Chaturvedi, M. Sharma, Int. J. Chem. Sc. 8 (2010) 1580.
(
CRediT authorship contribution statement
[
[
34] Y.-C. Wang, A.-H. Lee, C.-C. Chen, J. Taiwan Inst. Chem. Eng. 93 (2018) 315.
35] S.J. Sabounchei, M. Hosseinzadeh, M. Zarepour-jevinani, B. Ghanbari, New J.
Chem. 41 (2017) 9701.
Elahe Rahimzade: Formal analysis, Investigation, Methodology.
Mojgan Ghanbari: Writing – review & editing, Writing – original
draft, Investigation, Software. Hassan Abbas Alshamsi: Writing –
review & editing, Validation. Maryam Karami: Investigation.
Mahin Baladi: Investigation. Masoud Salavati-Niasari: Conceptu-
alization, Project administration, Visualization, Writing – original
draft, Writing – review & editing, Supervision, Visualization, Vali-
dation, Data curation.
[36] X.-T. Yin, J. Li, D. Dastan, W.-D. Zhou, H. Garmestani, F.M. Alamgir, Sens.
Actuators, B 319 (2020) 128330.
[
[
37] J. Tang, D. Li, Z. Feng, Z. Tan, B. Ou, RSC Adv. 4 (2014) 2151.
38] M. Karami, M. Ghanbari, O. Amiri, M. Salavati-Niasari, Sep. Purif. Technol.
(2020) 117526.
[
[
39] I.K. Konstantinou, T.A. Albanis, Appl. Catal. B 49 (2004) 1.
40] S.J. Sabounchei, M. Hosseinzadeh, A. Hashemi, S. Salehzadeh, F. Maleki, Dalton
Trans. 45 (2016) 13899.
[41] S.J. Sabounchei, M. Hosseinzadeh, S. Salehzadeh, F. Maleki, R.W. Gable, Inorg.
Chem. Front. 4 (2017) 2107.
[
[
42] F. Razi, S. Zinatloo-Ajabshir, M. Salavati-Niasari, J. Mol. Liq. 225 (2017) 645.
43] M. Ghanbari, M. Sabet, M. Salavati-Niasari, J. Mater. Sci.: Mater. Electron. 27
Declaration of Competing Interest
(
2016) 11092.
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared
to influence the work reported in this paper.
[44] F. Razi, F. Soofivand, M. Salavati-Niasari, J. Mol. Liq. 222 (2016) 435.
10