View
2
Download
0
Category
Preview:
Citation preview
www.nanoadv.org
Research Article
Nano Adv., 2018, 3, 12−17.
2016, 1, X−X. Nano Advances
http://doi.org/10.22180/na221 Volume 3, Issue 2, 2018
CO2 Induced Synthesis of Zn-Al Layered Double Hydroxide Nanostructures towards Efficiently Reducing Fire Hazards of Polymeric Materials
Xin Wang,a* Ehsan Naderi Kalali,
b Weiyi Xing,
a and De-Yi Wang
b*
a State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026, Anhui
Province, P. R. China
b IMDEA Materials Institute, C/Eric Kandel, 2, 28906 Getafe, Madrid, Spain
*Corresponding author. E-mail: wxcmx@ustc.edu.cn (X. Wang); deyi.wang@imdea.org (D. Y. Wang)
Received December 9, 2017; Revised February 4, 2018
Citation: X. Wang, E. N. Kalali, W. Xing, and D. Y. Wang, Nano Adv., 2018, 3, 12-17.
Improving the flame retardancy of polymeric materials is an imperative yet challenging task without deteriorating
their intrinsic properties. Herein, we reported a facile approach to grow zinc-aluminum layered double hydroxide
(Zn-Al LDH) nanostructures on the surfaces of polymer substrates in order to overcome their high fire hazards. CO2
induced growth of Zn-Al LDH allowed slow and homogeneous nucleation, leading to the as-synthesized Zn-Al LDH
with ultra-large size (several microns) and perfect hexagonal shape. The Zn-Al LDH uniformly covered the surfaces
of substrates and provided excellent flame-retardant effect. Cone calorimeter measurements revealed that the peak
heat release rate of Zn−Al LDH-coated wood and rigid polyurethane foam (RPUF) were significantly decreased by 55%
and 51%, respectively, compared to those of the pristine wood and RPUF; also, Zn−Al LDH-coated wood and RPUF
showed notable reduction in total smoke production up to 47% and 28%, respectively. These findings demonstrate
that CO2 induced synthesis of Zn-Al LDH nanostructures is a feasible and effective solution to polymeric materials
with desirable flame-retardant and smoke-suppression properties.
KEYWORDS: CO2 induced synthesis; Layered double hydroxides; Flame retardancy; Wood; Polyurethane foam
1. Introduction
Polymeric materials have found a wide variety of applications
and brought substantial convenience to modern society in
everyday life. Despite of numerous advantages, polymeric
materials, including natural polymers and synthetic polymers,
possess a major problem because most of them are composed of
organics and thus flammable. The flammability restricts their
application in the fields of electrical and electronic devices,
furniture, and building and transportation materials. Flame
retardant additives are most commonly used to reduce the fire
hazards of polymers. However, these additives also encounter a
dilemma, such as negative impact on health and environments
during the combustion,1,2 and deterioration in mechanical and/or
thermal properties.3 Consequently, there is increasing demand
for developing novel flame retardant technology for polymeric
materials.
Layered double hydroxide (LDH), also known as anionic clay,
is an important host-guest material that is composed of positively
charged metal hydroxide sheets with anions and water molecules
within the layers.4 The general chemical formula of LDHs can be
represented as [M2+1−xM
3+x(OH)2]
x+·[(An−)x/n·yH2O]x-, where
M2+, M3+, and An−denote divalent and trivalent metal cations,
and interlayer anions, respectively.5 Due to the highly tunable of
M2+, M3+, and An− as well as the “x” value, various composition
of LDHs have been prepared. LDHs have been widely
investigated as photocatalysts,6 dye absorbents,7 drug carriers8
and flame retardants.9, 10 As one kind of well-known flame
retardant, LDH has been intensively studied as additives to blend
with polymeric materials. Under this situation, the flame
retardant improvement depends strongly upon the dispersion of
LDHs, and the addition of LDHs might alter the intrinsic
properties of polymer matrix as well.
As an alternative solution, in recent years, construction of
coatings on the polymeric materials using nano-materials has
attracted considerable interests because the presence of these
nanocomposite coatings could greatly improve the flame
resistance of polymer substrates without destructing the intrinsic
12
Research Article Nano Advances
Nano Adv., 2018, 3, 12−17.016, 1, X−X.
doi: 10.22180/na221
properties. Over the last decade, multi-layered coatings consisted
of various nano-materials, including montmorillonite,11–13
graphene,14 zirconium phosphate,15 LDH,12,16 polyhedral
oligomeric silsesquioxanes,17 have been deposited onto polymer
substrates through the layer-by-layer (L-b-L) assembly technique.
These nanocomposite coatings built by the L-b-L method have
been demonstrated to be effective in suppressing flame spread
and/or reducing heat release rate of cotton fabrics,17,18 polyester
fabrics,15 polyurethane foams,12,14 cellulose aerogels.13 However,
the L-b-L technique requires multiple immersion-washing-drying
cycles, which consumes a long time. Very recently, a two-step
hydrothermal process was reported to fabricate Mg−Al LDH
coating on a wood substrate.19 Significant reduction in peak heat
release rate (-49%) and total smoke production (-58%) were
observed in the Mg−Al LDH-coated wood in comparison to the
untreated wood, but the hydrothermal process limits its scalable
production.
Up to now, LDHs are mainly synthesized through two routes:
co-precipitation6,7 and hydrothermal method.20,21 However, the
LDHs prepared by these two methods usually show small lateral
size, low specific surface area and crystalline defect.6,7,21 In this
work, we developed a new and simple approach to synthesize the
Zn-Al LDH through exposing the mixed alkali solution of
divalent and trivalent metal ions to air atmosphere. With the
transformation of CO2 into CO32− as the interlayer anions, the
Zn-Al LDH with ultra-large size, high specific surface area and
beautiful crystalline structure was coated on the polymeric
materials, such as wood and rigid polyurethane foam (RPUF), to
confer flame-retardant properties.
2. Experimental
2.1 Materials
Zinc nitrate hexahydrate, aluminum nitrate nonahydrate and
sodium hydroxide were purchased from Sigma-Aldrich Reagents
Company and used as received. Deionised water is used for all
experiments unless otherwise stated. A heartwood section of
China fir wood was purchased from local market and cut into
specialized size for measurements. Rigid polyurethane foams
(RPUFs) were made in our laboratory according to the receipt
(Table S1).
2.2 Carbon dioxide induced synthesis of layered double
hydroxide
ZnAl-LDH was synthesized induced by carbon dioxide, as
shown in Scheme 1. Briefly, zinc nitrate hexahydrate (0.02 mol)
was dissolved in deionised water (20 ml) and subsequently 2 M
sodium hydroxide aqueous solution was added into it dropwise
until the resultant white precipitate re-dissolved to obtain a
transparent solution (A). Meanwhile, aluminium nitrate
nonahydrate (0.01 mol) was also dissolved in deionised water
(20 ml) and subsequently treated by 2 M sodium hydroxide
aqueous solution dropwise until the resultant white precipitate
re-dissolved to obtain a transparent solution (B). The solution A
was mixed with the solution B and then diluted to 500 ml by the
deionised water. The wood board or rigid polyurethane foam was
placed at the bottom of the mixture, followed by exposing to air
statically for 12 h. During this period, the transparent mixture
gradually became muddy, and the resultant white precipitate was
deposited onto the wood board or rigid polyurethane foam, and
then dried in the oven at 60 °C for 48 h.
2.3 Characterization
The powder X-ray diffraction (XRD) patterns were carried out
on a Philips X’Pert PRO diffractometer (Netherlands) equipped
with Cu Kα radiation (λ = 0.15405 nm), operating at 45 kV
voltage and 40 mA current. Fourier transformed infrared (FTIR)
spectra were recorded on a NICOLET iS50FTIR spectrometer
(USA) using KBr disc method. Thermogravimetric analysis
(TGA) of the samples was measured on a Q50 thermal analyzer
(TA Instruments, USA) in air atmosphere from 30 to 800 °C at a
heating rate of 10 °C/min. Transmission electron microscopy
(TEM) images were observed using a Talos F200X microscopy
(FEI, Netherlands) combining outstanding high-resolution TEM
imaging. The morphology was investigated using an EVO MA15
Scheme 1. CO2 induced synthesis of Zn-Al layered double hydroxide nanostructures on polymeric materials.
13
Research Article Nano Advances
Nano Adv., 2018, 3, 12−17.016, 1, X−X.
doi: 10.22180/na221
scanning electron microscopy (SEM, Zeiss, Germany). The
samples were sputtered with a conductive gold layer before SEM
observation. To determine the thickness of the Zn-Al LDH
coatings, a clean glass plate was put into the solution instead of
polymeric materials. After 12 h, the glass plate was washed,
dried and then observed using SEM. The combustion behaviors
of the samples were assessed by a cone calorimeter (Fire Testing
Technology, UK) according to the standard ISO 5660-1. Squared
specimens (100 mm × 100 mm × 10 mm) were horizontally
exposed to a heat flux of 50 kW·m–2.
3. Results and discussion
The structure of the Zn-Al LDH induced by CO2 was
characterized by wide angle X-ray diffraction (Figure 1a). As
can be observed, the Zn-Al LDH displays the typical features of
LDH materials with sharp intense peaks at low theta values,
while they become weaker and less defined at higher angular
values. The characteristics peaks at 2theta = 11.7o, 23.4o and
34.8o are attributed to the (003), (006) and (009) diffraction
peaks, respectively.22 As is well known, the d(003)-spacing is
equal to the basal spacing of LDH materials.23 From the basal
reflection (003) at 2theta = 11.7o, the basal spacing of Zn-Al
LDH is estimated to be 0.76 nm according to the Bragg equation.
This value is in good coincidence with the value for
carbonate-intercalated LDH materials.23 Furthermore, all the
diffraction peaks appear to be of very sharp shape, implying the
large-size crystalline obtained under free growth condition.
The FTIR spectrum of the Zn-Al LDH (Figure 1b) clarifies the
characteristic peaks of hydrotalcite-like compounds. The wide
and strong peak centered at 3454 cm−1 is assigned to the
stretching of the hydroxyl groups and water molecules. The
weak peak at 1620 cm−1 can be attributed to the bending
vibration of the interlayer water. The strong peaks around 1380
and 671 cm−1 are ascribed to the anti-symmetric stretching
vibration and the angular bending mode of carbonate,
respectively.24
The TG and differential TG curves (Figure 1c) of the Zn-Al
LDH reveals two major stages of mass loss. These two stages
locate at around 155 and 245 °C, respectively, as clearly
observed in the differential TG curve. The first one corresponds
to the loss of adsorbed moisture and interlayer water molecules,
while the second one is owing to the release of water loosely
coordinated to the interlayer carbonate.7
The TEM image (Figure 1d) reveals a regular hexagonal
platelet of the Zn-Al LDH. The selected area electron diffraction
(SAED) pattern (inset in Figure 1d) shows hexagonally arranged
spots, indicating a typical single crystalline of the material, in
good agreement with the XRD results.
The formation mechanism of Zn-Al LDH is proposed as
follows: an aqueous precursor solution containing Na2ZnO2 and
NaAlO2 is exposed to air via carbon dioxide induced
co-precipitation. The Na2ZnO2 is obtained from solubilising
Zn(OH)2 by excessive NaOH solution (Equation 1). Similarly,
the NaAlO2 is obtained from solubilising Al(OH)3 by excessive
NaOH solution (Equation 2). Simultaneously, CO2 is turned into
CO32− and intercalated into the interlayer gallery as anion. Due to
the excessive existence of NaOH and the low solubility of CO2
in solution, this aqueous precursor solution provides an alkaline
medium favourable for heterogeneous nucleation of Zn-Al LDH
(Equation 3).
( ) ( )
( ) (2)
[
( ) ] (
) (3)
SEM micrographs were taken to provide morphological
information of the Zn-Al LDH nanostructures on wood
substrates. Figure 2 gives the SEM images of the untreated wood,
Zn-Al LDH coated wood and the corresponding EDX elemental
mapping analysis. As can be observed, untreated wood shows a
rough surface consisted of many fibre bundles (Figure 2a). In
contrast, the treated wood exhibits a Zn−Al LDH nanostructure
coating contained numerous hexagonal platelets with the average
size of several microns (Figure 2b). High-magnification
observations of the Zn−Al LDH coating indicates an ultra-large
size (> 5 μm) and beautiful hexagonal shape of Zn-Al LDH
obtained through the CO2 induced growth method (Figure 2c).
Table S2 compares the as-prepared Zn-Al LDH with their
counterparts in the previous reports.6,7,21,24,25 Most of the Zn-Al
LDH reported up to now exhibits smaller size and irregular
shape. This is attributed to that the CO2 induced growth of Zn-Al
LDH allows slow and homogeneous nucleation in comparison to
the conventional methods (co-precipitation or hydrothermal
method). The elemental composition measured by EDX analysis
(Figure 2d) reveals that high percentages of Zn and Al elements
are clearly detected on the surface of the coated wood samples
besides C and O elements corresponding to the wood
Figure 1. (a) Wide angle X-ray scattering profile; (b) FTIR spectrum; (c)
Thermogravimetric analysis curve and (d) TEM images (Inset: the
corresponding SAED pattern) of the Zn-Al LDH induced by CO2.
14
Research Article Nano Advances
Nano Adv., 2018, 3, 12−17.016, 1, X−X.
doi: 10.22180/na221
components. Additionally, the EDX mapping images (Figure 2e
and 2f) confirm that the Zn and Al elements are distributed
uniformly on the wood surfaces. Similar phenomenon is
observed in the RPUF and Zn-Al LDH coated RPUF, as shown
in Figure S1 in the supporting information. In short, the SEM
and EDX analyses demonstrate that the Zn−Al LDH has been
prepared successfully and uniformly deposited onto the wood
and RPUF surfaces.
The influence of the loadings of the deposition mixtures on the
growth of the Zn-Al LDH coatings was also investigated. Four
different amounts of Zn and Al ions are used to prepare the
Zn-Al LDH coatings whose growth is shown in Figure 3. All
four formulations grew linearly as a function of amounts of Zn
and Al ions deposited. The coating thicknesses ranged from
several to hundred micrometers. So, it is very convenient to
control the coating thicknesses by adjusting the loading of Zn
and Al ions.
The XPS survey spectra of the wood, Zn-Al LDH coated wood,
RPUF and Zn-Al LDH coated RPUF are shown in Figure 4. The
relative intensity of C1s and O1s of Zn-Al LDH coated wood is
lower than that in the untreated wood, suggesting that the Zn-Al
LDH is covered on the wood surface. In addition, peaks at
1044.5 and 74.3 eV in the Zn−Al LDH-coated wood are assigned
to the Zn2p and Al2p binding energies in Zn−Al LDH,
respectively. Similar phenomenon is observed in the RPUF and
Zn-Al LDH coated RPUF. These findings further confirm that
Zn−Al LDH has been successfully synthesized on the surfaces of
polymer substrates.
The fire protection effect of the Zn−Al LDH coating on the
wood and RPUF was investigated using cone calorimeter. As
one of the most important parameter obtained in cone
calorimeter, the heat release rate (HRR) is usually used to assess
the intensity of flame. The peak HRR values of the Zn−Al
LDH-coated wood and RPUF are significantly decreased by 55%
and 51%, respectively, compared to those of the pristine wood
Figure 2. SEM images of (a) untreated wood and (b, c) Zn-Al LDH coated
wood under different magnifications. (d) EDX elemental mapping analysis of
(e) Zn, and (f) Al of the Zn−Al LDH-coated wood.
Figure 3. Zn-Al LDH coating thickness as a function of the Zn and Al ions
amount.
Figure 4. XPS survey of untreated wood and the Zn−Al LDH-coated wood,
and untreated RPUF and the Zn−Al LDH-coated RPUF. XPS high-resolution
spectra of Al2p and Zn2p of the Zn−Al LDH-coated wood and the Zn−Al
LDH-coated RPUF.
15
Research Article Nano Advances
Nano Adv., 2018, 3, 12−17.016, 1, X−X.
doi: 10.22180/na221
and RPUF (Figure 5a and 5e). Accompanying with the
significantly reduced peak HRR values of the Zn−Al
LDH-coated samples, their time to ignition (TTI) and time to
peak HRR values slightly change (Table 1). The fire growth rate
index (FIGRA), calculated by the ratio of PHRR and time to
PHRR,26 is usually used to evaluate the flame propagation rate of
materials. The FIGRA values of the Zn−Al LDH-coated wood
and RPUF are dramatically reduced in comparison to the
untreated ones (Table 1), indicating the suppressed fire hazard
quality of the materials. With the presence of the Zn−Al LDH
coating, the total heat release (THR) values of the treated wood
and RPUF are decreased by 19% and 17%, respectively,
compared to those of the untreated wood and RPUF (Figure 5b
and 5f). A comparison of the performance of Zn-Al LDH coating
with other flame retardant coatings is summarized in Table S3.
The current Zn-Al LDH coating exhibits better flame retardant
effect than other flame retardant coatings made by layer-by-layer
assembly such as chitosan and poly(phosphoric acid),27 chitosan
and poly(vinyl sulfonic acid sodium salt),28
poly(diallydimethylammonium chloride), poly(acrylic acid) and
ammonium polyphosphate,29 brucite,
3-aminopropyltriethoxysilane and alginate.30 Flame retardant
effect is similar to that of Mg−Al LDH coating,19 but the current
coating is easier to achieve scalable production.
Furthermore, both the Zn−Al LDH-coated wood and RPUF
show notable reduction in total smoke production (TSP) up to 47%
and 28%, respectively, compared to that of pristine samples
(Figure 5c and 5g). The decreased TSP can be explained by that
the presence of Zn−Al LDH coating served as physical barrier to
restrain organic macromolecules from converting into the
organic volatiles that are the major source of smoke particles.31
This phenomenon is also supported by the decreased av-EHC
values (Table 1), suggesting that lower amount of volatile gases
(fuels) goes into gaseous-phase. CO production, regarding the
toxicity of gas released from combustion of samples, is the major
reason for casualties in fire incidents.32 The CO production
versus time curve (Figure 5d and 5h) shows that the CO
production of the Zn−Al LDH-coated samples is significantly
decreased by 41% and 29%, respectively, compared to that of
pristine samples. These dramatic reductions in smoke and toxic
CO production are beneficial to evacuation and rescue when an
incident happens.
These improved fire retardant properties induced by Zn-Al
LDH can be attributed to the heat absorption and char formation.
During the degradation process, LDHs lose the interlayer water
molecule, which is an endothermic reaction.33 LDHs can absorb
a large amount of heat and meanwhile the water vapor dilute the
Figure 5. (a, e) HRR, (b, f) THR, (c, g) SEA and (d, h) CO production versus
time curves of wood, Zn-Al LDH-coated wood, RPUF and Zn-Al LDH-coated
RPUF, respectively.
Table 1. Cone calorimeter data of wood, RPUF before and after LDH treatment
Sample TTI (s) PHRR (kW/m2) THR (MJ/m2) Av-EHC (MJ/kg) Time to PHRR (s) FIGRA (kW/(m2·s))
Wood 11 340 18.45 11.05 110 3.09
LDH-Wood 10 152 14.99 8.10 108 1.41
RPUF 2 325 13.97 20.11 10 32.5
LDH-RPUF 3 159 11.59 15.51 12 13.3
16 16
Research Article Nano Advances
Nano Adv., 2018, 3, 12−17.016, 1, X−X.
doi: 10.22180/na221
flammable volatiles, and thus, the heat release rate is suppressed.
From the digital photograph of the char residue, it can be
observed that a white inorganic layer is formed on the surface of
LDH-wood compared to pristine sample (Figure S2a and S2b).
For the RPUF, almost no residue is left after the cone calorimeter
and the aluminium foil is burned out (Figure S2c). In contrast,
the LDH-RPUF shows much more residue (Figure S2d). The
increased char yield is also evidenced by the mass loss profiles
as a function of burning time (Figure S3). The formation of such
a char layer functions as a physical barrier to inhibit the mass
and heat transfer between polymeric substrates and flame.
4. Conclusions
In summary, we developed a facile CO2 induced synthesis
method to deposit Zn-Al LDH coatings onto the surfaces of
polymeric materials including wood and rigid polyurethane foam
(RPUF). The morphology and chemical compositions
characterized by SEM and EDX spectroscopy confirmed that the
Zn-Al LDHs were uniformly covered on the surfaces of
substrates. The presence of the Zn-Al LDH coating resulted in
significantly improved fire retardancy of polymeric materials.
Cone calorimeter results showed that the peak heat release rate
of the Zn−Al LDH-coated wood and RPUF was reduced by 55%
and 51%, respectively, compared to those of the pristine wood
and RPUF; also, notable reduction in total heat release, total
smoke production, and CO production were also observed. This
flame retardant treatment reported herein provides an innovative
and efficient strategy to reduce fire hazards of polymeric
materials.
Acknowledgements
We gratefully acknowledge financial support from the National
Natural Science Foundation of China (Grant No. 21604081), and
Anhui Provincial Natural Science Foundation (1608085QE99).
Notes and references
Supporting information for this article is available: Figures
S1-S3 and Table S1-S3 mentioned in the text. See doi:
10.22180/na221.
1. S. Kemmlein, O. Hahn, and O. Jann, Atmos. Environ., 2003, 37,
5485.
2. M. M. Zhang, A. Buekens, and X. D. Li, J. Hazard. Mater., 2016,
304, 26.
3. N. A. Isitman, and C. Kaynak, Polym. Degrad. Stabil., 2010, 95,
1523.
4. D. Y. Wang, F. R. Costa, A. Vyalikh, A. Leuteritz, U. Scheler, D.
Jehnichen, U. Wagenknecht, L. Haussler, and G. Heinrich, Chem.
Mater., 2009, 21, 4490.
5. E. N. Kalali, X. Wang, and D. Y. Wang, J. Mater. Chem. A, 2015, 3,
6819.
6. Y. F. Zhao, G. B. Chen, T. Bian, C. Zhou, G. I. N. Waterhouse, L. Z.
Wu, C. H. Tung, L. J. Smith, D. O'Hare, and T. R. Zhang, Adv.
Mater., 2015, 27, 7824.
7. C. Chakraborty, K. Dana, and S. Malik, J. Phys. Chem. C, 2011,
115, 1996.
8. S. Senapati, R. Thakur, S. P. Verma, S. Duggal, D. P. Mishra, P. Das,
T. Shripathi, M. Kumar, D. Rana, and P. Maiti, J. Control Release,
2016, 224, 186.
9. H. Y. Xie, Q. Ye, J. Y. Si, W. Yang, H. D. Lu, and Q. Z. Zhang,
Polym. Adv. Technol., 2016, 27, 651.
10. X. Wang, E. N. Kalali, and D.Y. Wang, Nano Adv., 2016, 1, 1.
11. Y. C. Li, J. Schulz, S. Mannen, C. Delhom, B. Condon, S. Chang, M.
Zammarano, and J. C. Grunlan, ACS Nano, 2010, 4, 3325.
12. Y. H. Yang, Y. C. Li, J. Shields, and R. D. Davis, J. Appl. Polym.
Sci., 2015, 132, 41767.
13. O. Koklukaya, F. Carosio, and L. Wagberg, ACS Appl. Mater.
Interfaces, 2017, 9, 29082.
14. H. F. Pan, B. H. Yu, W. Wang, Y. Pan, L. Song, and Y. Hu, RSC Adv.,
2016, 6, 114304.
15. F. Carosio, J. Alongi, and G. Malucelli, J. Mater. Chem., 2011, 21,
10370.
16. H. F. Pan, W. Wang, Q. Shen, Y. Pan, L. Song, Y. Hu, and Y. S. Lu,
RSC Adv., 2016, 6, 111950.
17. Y. C. Li, S. Mannen, J. Schulz, and J. C. Grunlan, J. Mater. Chem.,
2011, 21, 3060.
18. S. S. Chen, X. Li, Y. Li, and J. Q. Sun, ACS Nano, 2015, 9, 4070.
19. B. Guo, Y. Liu, Q. Zhang, F. Wang, Q. Wang, Y. Liu, J. Li, and H.
Yu, ACS Appl. Mater. Interfaces, 2017, 9, 23039.
20. J. H. Huang, Z. H. Yang, R. J. Wang, Z. Zhang, Z. B. Feng, and X. E.
Xie, J. Mater. Chem. A, 2015, 3, 7429.
21. P. Benito, I. Guinea, F. M. Labajos, J. Rocha, and V. Rives,
Micropor. Mesopor. Mat., 2008, 110, 292.
22. S. Aisawa, H. Kudo, T. Hoshi, S. Takahashi, H. Hirahara, Y. Umetsu,
and E. Narita, J. Solid State Chem., 2004, 177, 3987.
23. M. Wei, X. Y. Xu, X. R. Wang, F. Li, H. Zhang, Y. L. Lu, M. Pu, D.
G. Evans, and X. Duan, Eur. J. Inorg. Chem., 2006, 14, 2831.
24. F. Z. Mahjoubi, A. Khalidi, M. Abdennouri, and N. Barka, J. Taibah
Univ. Sci., 2017, 11, 90.
25. S. Li and B. Bhushan, Appl. Surf. Sci., 2016, 378, 308.
26. X. Wang, E. N. Kalali, and D. Y. Wang, ACS Sustainable Chem.
Eng., 2015, 3, 3281.
27. F. Carosio and J. Alongi, ACS Appl. Mater. Interfaces, 2016, 8,
6315.
28. G. Laufer, C. Kirkland, A. B. Morgan, and J. C. Grunlan, ACS
Macro Lett., 2013, 2, 361.
29. F. Carosio, F. Cuttica, A. D. Blasio, J. Alongi, and G. Malucelli,
Polym. Degrad. Stabil., 2015, 113, 189.
30. Y. Wang, X. Yang, H. Peng, F. Wang, X. Liu, Y. Yang, and J. Hao,
ACS Appl. Mater. Interfaces, 2016, 8, 9925.
31. Y. Y. Dong, Z. Gui, Y. Hu, Y. Wu, and S. H. Jiang, J. Hazard.
Mater., 2012, 209, 34.
32. X. Wang, L. Song, H. Y. Yang, W. Y. Xing, H. D. Lu, and Y. Hu, J.
Mater. Chem., 2012, 22, 3426.
33. J. H. Yang, W. Zhang, H. Ryu, J. H. Lee, D. H. Park, J. Y. Choi, A.
Vinu, A. A. Elzatahry, and J. H. Choy, J. Mater. Chem. A, 2015, 3,
22730.
How to cite this article: X. Wang, E. N. Kalali, W. Xing, and D.
Y. Wang, Nano Adv., 2018, 3, 12−17. doi: 10.22180/na221.
17
Recommended