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- Journal of Science: Advanced Materials and Devices 6 (2021) 27e32
Contents lists available at ScienceDirect
Journal of Science: Advanced Materials and Devices
journal homepage: www.elsevier.com/locate/jsamd
Original Article
High acetone-sensing performance of bi-phase a-/g-Fe2O3 submicron
flowers grown using an iron plate
Vu Xuan Hien a, *, Luong Huu Phuoc a, Cao Tien Khoa b, Dang Duc Vuong a,
Nguyen Duc Chien a
a
School of Engineering Physics, Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hanoi, Viet Nam
b
Department of Physics, Thai Nguyen University of Education, 20 Luong Ngoc Quyen Street, Thainguyen, Viet Nam
a r t i c l e i n f o a b s t r a c t
Article history: Iron oxide nanostructures have been studied extensively because of their excellent magnetic, optical,
Received 6 June 2020 electrical, and catalytic properties. This work introduces a simple process to synthesize directly bi-phase
Received in revised form a-/g-Fe2O3 submicron flowers on a Fe foil in NH4OH. The flowers were assembled by using many
8 September 2020
nanoplates with an estimated thickness of 20e80 nm. The shapes and dimensions of the flowers can be
Accepted 14 September 2020
controlled by the treatment time. The gas-sensing properties of the a-/g-Fe2O3 submicron flowers were
Available online 17 September 2020
investigated at different gas concentrations (125e1500 ppm) and operating temperatures (200e360 C).
The results obtained indicate that the as-synthesized material exhibits an excellent acetone-sensing
Keywords:
Iron oxides
characteristic and has the potential for practical applications.
Metal © 2020 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi.
Nanoplates This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Surface reaction
Gas sensors
1. Introduction issue, several studies have pre-treated the metal surface in alkaline
solutions to modulate the morphology [11]. This method has been
Many metal oxide semiconductors (MOSs), such as TiO2, SnO2, effectively used with Cu to synthesize Cu(OH)2 and CuO [12e14].
WO2, NiO, Co3O4, and Fe2O3, have attracted great attention because Nevertheless, few studies have applied the similar method to Fe.
of their wide range of applications. Fe2O3 is an n-type semi- a-Fe2O3 is an excellent candidate for gas sensors [15e17]. The
conductor that is naturally abundant, non-toxic and inexpensive particle-like, rod-like and plate-like nanostructures of a-Fe2O3, and
and has interesting electrical/catalytic characteristics [1]. Many g-Fe2O3, have been investigated for gas-sensing applications
methods have been proposed to synthesize nano/microstructures [18e20]. Most gas sensors with metal oxides, such as SnO2, ZnO,
of Fe2O3. Some of these methods are hydrothermal treatment, self- and a-Fe2O3, are surface resistance controlled sensors [21]. g-Fe2O3,
assembly, sputtering, chemical vapor deposition (CVD), and wet which has a spinel-type structure, is one of the few materials with
chemical processing [2e6]. Fe2O3 nanowires have been grown the bulk resistance controlled effect [22,23]. Therefore, the com-
easily and directly on an iron plate surface by thermal oxidation or bination of these two phases is proposed to exploit the surface
the hot-plate technique [7,8]. However, in this method, modifying versus bulk sensitivity, thereby improving the gas sensing proper-
the sample morphology by modulating the treatment temperature ties of the material. Ming et al. claimed that the ethanol-sensing
or time is nearly impossible [9,10]. This limitation is observed in all- properties of the bi-phase a-/g-Fe2O3 nanostructure are at least
metal oxides grown by thermal oxidation (e.g. CuO nanowires on a thrice higher than those of g-Fe2O3 [22]. However, no further
Cu foil/foam and NiO nanowalls on a Ni foil) [9]. To overcome this research on this material has been conducted. In addition to the
phase variation, the flower-like nano/microstructures have recently
attracted great attention, because this morphology can improve the
effective working/sensing areas and increase the pore size [24]. In
* Corresponding author. School of Engineering Physics, Hanoi University of Sci- this study, the micro flowers constructed by using a-/g-Fe2O3
ence and Technology (HUST), No. 01 Dai Co Viet Street, Hanoi, Viet Nam. Fax: þ84
436231713.
nanoplates are synthesized by treating an iron plate in aqueous
E-mail address: hien.vuxuan@hust.edu.vn (V.X. Hien). NH4OH near room temperature and subsequently annealing at
Peer review under responsibility of Vietnam National University, Hanoi. 500 C. The effects of the treatment time on the formation of the
https://doi.org/10.1016/j.jsamd.2020.09.011
2468-2179/© 2020 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/).
- V.X. Hien, L.H. Phuoc, C.T. Khoa et al. Journal of Science: Advanced Materials and Devices 6 (2021) 27e32
micro flowers are investigated. The sample after the heat treatment 3. Results and discussion
was tested with acetone, ethanol, and liquified petroleum gas (LPG)
at 200e360 C. The XRD patterns of the red powders treated for 24e120 h are
shown in Fig. 1a. The main phase in all samples is FeOOH, and the
2. Experimental major diffraction peaks at 2q of 27, 29.9 , 36.2 , and 46.8 can be
assigned to the (021), (110), (041) and (002) planes of FeOOH [JCPDS
In this experiment, a commercial iron plate of 0.25 mm file No. 98-010-8876, orthorhombic structure, space group Cmcm
thickness and NH4OH solution of 25% concentration were used as (63)]. Two additional phases of Fe(OH)2 [JCPDS file No. 00-003-
precursors. First, the iron plate was carefully ground by a grind- 0903, hexagonal structure, space group P-3m1 (164)] and
stone and fine sandpaper to remove the oxide layer. Then, the iron Feþ3O(OH) [JCPDS file No. 00-017-0536, orthorhombic structure,
plate was cut into 2 2 cm2 squares. The cut plate was ultra- space group Pbnm (62)] are detected with the minor peaks at 33.2 /
sonically cleaned in a bath sonicator with acetone for 5 min. After 36.6 and 34.7 /35.5 /67.1, respectively. No other impurities are
being dried under a flow of N2, the plate was folded at the corners found.
to form a table-like plate, and 25 mL of NH4OH solution in a 100- Hydroxide forms of iron can be dehydrated to form Fe2O3
mL Duran laboratory bottle was added. The bottle was capped and above 300 C [22]. The phase transformation of the as-synthesized
placed in a large chemical bottle (total volume of 400 mL) filled sample was investigated at 400 C and 500 C for 1 h (Fig. 1b). All
with 150 mL of distilled water. After covering the cap with an peaks in the XRD pattern of the sample annealed at 400 C could
aluminium foil, the large bottle was heated by a hot plate that was be assigned to the cubic structures of g-Fe2O3 [JCPDS file No. 98-
controlled by a proportional integral derivative temperature 024-7034, cubic structure, space group Fd-3m (227)]. At the
controller (the K-type thermocouple was dipped into the distilled annealing temperature of 500 C, the phase of a-Fe2O3 [JCPDS file
water). The treatment temperature was 40 C at a heating rate of No. 01-089-0597, rhombohedral structure, space group R-3c (167)]
1 C/min, and different treatment times in the range of 1e5 days is formed along with the g-Fe2O3 background. No other phase was
were carried out. After the heat treatment, the Duran bottle was found in the patterns. Therefore, it is confirmed that the FeOOH
treated in a bath sonicator for 5 min. A red precipitate was washed phase was completely transformed to the bi-phase a-/g-Fe2O3 by
and extracted from the treated solution by distilled water and by annealing at 500 C in 1 h.
centrifugation, respectively. The red powder was annealed in a Fig. 2 introduces the surface morphologies of all samples treated
horizontal furnace at 500 C for 1 h to produce Fe2O3 [25]. To for 24e120 h after annealing at 500 C for 1 h. The sample treated
fabricate the sensing device, the annealed powder was coated on for 24 h is composed of nanoplates with different dimensions and
an interdigitated electrode (gap, ~20 mm) by spin-coating (coating rough surfaces (Fig. 2a). When the treatment time is prolonged to
speed of 3000 rpm; coating time of 2 min). The electrode shape is 48 h, the surfaces of the nanoplates are smooth, and the plates are
shown in Fig. S1 (Supplemental Information). apparently assembled in random directions (Fig. 2b). In Fig. 2c, the
The red powder before annealing was characterized by field- sample treated for 72 h has a flower-like microstructure (with
emission scanning electron microscopy (FE-SEM; JEOL JSM- diameter of 500e2000 nm). The petals are nanoplates arranged in
7610F), and the structures were evaluated by X-ray diffraction different orientations. The average plate thickness was estimated to
(XRD; X'Pert-Pro) by using Cu Ka radiation (l ¼ 1.5418 Å). Gas- be 40 nm. Many microspheres with rough surfaces are distributed
sensing measurement was performed in a static gas-testing sys- in some areas of the sample. The petal/plate is thicker (~70 nm)
tem with a working chamber of 20 L. The gas-testing system is when the treatment time is 96 h (Fig. 2d). In addition, the nano-
presented in Fig. S2 (Supplemental Information). The sensor plates are more uniform and distributed on the whole sample
response was calculated as follows: surface without any microspheres. When the treatment time is
extended to 120 h, the sample has apparently aged, and micro-
Ra Rg spheres are primarily observed (Fig. 2e).
s¼ (1) A graph comparing the acetone responses of the samples heated
Rg
at 400 C and 500 C is shown in Fig. 3. The gas response of the bi-
where Ra and Rg are the stable resistances of the device without and phase a-/g-Fe2O3 sample is nearly 9 times higher than that of the
with the target gas, respectively. single-phase g-Fe2O3. This result agrees with that in the study of
Fig. 1. XRD patterns of the samples treated at 40 C for 24 h (a1), 48 h (a2), 72 h (a3), 96 h (a4) and 120 h (a5); XRD patterns of the sample treated at 40 C for 96 h and annealed at
400 C (b1) and 500 C (b2) for 1 h.
28
- V.X. Hien, L.H. Phuoc, C.T. Khoa et al. Journal of Science: Advanced Materials and Devices 6 (2021) 27e32
Fig. 2. FE-SEM images of the samples treated at 40 C for 24 h (a), 48 h (b), 72 h (c), 96 h (d), and 120 h (e). All samples were annealed at 500 C for 1 h. The scale bar is 5 mm.
Ming et al., in which the surface resistance controlled type of a- where ads stands for adsorption. According to Eqs. (2)e(5), the
Fe2O3 has enhanced the sensing performance of the bulk resistance oxygen molecules and ions take the free electrons of a-Fe2O3 to
controlled type (g-Fe2O3) [22]. The gas-sensing behavior of the bi- increase the surface resistance of the material. These adsorbed
phase a-/g-Fe2O3 may comprise the gas-sensing mechanism of a- oxygen ions can react with reducing gases, e.g. acetone, ethanol,
Fe2O3 versus that of g-Fe2O3. As a surface resistance control sensor, and LPG, to return these free electrons of a-Fe2O3 as follows:
the resistance of a-Fe2O3 fluctuates by the reactions of the test gas
with the adsorbed oxygen ions formed by charge transfer chemi- CH3 COCH3 ðgÞ þ 8Ox ðadsÞ / 3CO2 ðgÞ þ 3H2 OðgÞ þ 8xe (6)
sorption [26,27] as follows:
C2 H5 OHðgÞ þ 6Ox ðadsÞ / 2CO2 ðgÞ þ 3H2 OðgÞ þ 6xe (7)
O2 ðgasÞ4O2 ðadsÞ (2)
C3 H8 ðgÞ þ 10Ox ðadsÞ / 3CO2 ðgÞ þ 4H2 OðgÞ þ 10xe (8)
O2 ðadsÞ þ e 4O
2 ðadsÞðT < 100 CÞ (3)
where x ¼ 1 or 2. Afterward, the free electrons generated by Eqs.
(6)e(8) can reduce the material resistance. Maghemite g-Fe2O3 is
O
2 ðadsÞ þ e 42O ðadsÞð100 C < T < 300 CÞ (4)
an n-type MOS with a bandgap of 2.03 eV. When placed in a
reducing gas environment, e.g. acetone, ethanol or LPG, g-Fe2O3 can
O ðadsÞ þ e 4O2 ðadsÞðT > 300 CÞ (5) be reduced to Fe3O4 [22] as follows:
Reduction
2 !
g Fe3þ
2 O3 Fe2þ O2 þ Fe3þ
2
2 O3 (9)
Oxidation
where Fe3O4 is known as a half-metal material and acts as a
conductor because of the continuous hopping of the electrons from
Fe2þ to Fe3þ cations over the crystallographic B-octahedral sites of
the inverse spinel structure (active by thermal energy) [28].
Therefore, the resistance of g-Fe2O3 is decreased during the expo-
sure to reducing gases. According to the sensing mechanism of a-
Fe2O3 versus g-Fe2O3, the sensing material is low selectivity to
reducing gases. The difference in gas responses is due to several
factors, such as the working temperature, morphology/structure,
and the diffusion ability of the test gas [29e31].
The resistor model that explains the response enhancement of
the a-/g-Fe2O3 over the g-Fe2O3 sample is shown in Fig. S3 (Sup-
plemental Information). In the model, the resistance of the g-Fe2O3
sample is Rg. After reacting with the reduced gas, e.g. acetone,
Fig. 3. Response/recovery curves of g-Fe2O3 (sample treated at 40 C for 96 h and
ethanol, or LPG, a portion of g-Fe2O3 is converted to Fe3O4 [Eq. (9)].
annealed at 400 C), and a-/g-Fe2O3 (sample treated at 40 C for 96 h and annealed at As a result, an electron channel is formed on the surface of g-Fe2O3
500 C). (Fig. S3b), which is equivalent to the resistor R34 (resistor of Fe3O4) in
29
- V.X. Hien, L.H. Phuoc, C.T. Khoa et al. Journal of Science: Advanced Materials and Devices 6 (2021) 27e32
parallel with Rg. The surface of g-Fe2O3 may be converted to a-Fe2O3 320 C (Fig. 4d and f). The enhanced response of the samples
because of the thermal oxidation. Therefore, the equivalent resis- treated for a long time may be related to the growth of the micro
tance circuit of the material possibly consists of an Ra resistor (a- flowers/nanoplates. The complete formation of the nanoplates as
Fe2O3 resistor) connected in series with Rg (Fig. S3c). After reacting petals may not only increase the effective working area of the
with the reducing gas as presented in Eqs. (6)e(9), the surface of the sensor but also improve the pore size of the film. As mentioned
material system can show two electronic conducting channels above, the sample treated for 120 h has apparently aged, which
coming from the surface of the a-Fe2O3 and Fe3O4 materials. These may result in the decline of the sensing performance (Fig. 4e). The
channels are equivalent to the resistors Ra23 and R34 in parallel with response versus recovery times of the sample treated for 96 h are
Ra-Rg (Fig. S3d). This resistor probably possesses a smaller value both approximately 25 s.
than that in the g-Fe2O3 sample. According to Eq. (1), the response of Fig. 5a introduces the effects of acetone/ethanol/LPG concen-
a-/g-Fe2O3 is evidently higher than that of g-Fe2O3. tration on the sensor response of the sample treated for 96 h. The
The acetone-sensing properties of all samples at operating result indicates that the sample is more sensitive towards acetone
temperatures of 200e360 C are shown in Fig. 4. The data indicate than to the other gases. At a concentration of 1500 ppm, the
that the gas response increases with the treatment time from 24 h acetone response is reasonably above 160, which is 3.2 and 10.6
to 96 h (Fig. 4aed). The highest response of the samples treated times higher than the responses of ethanol and LPG, respectively.
for 96 h is approximately 95, and the optimal temperature is The fitting lines of these data are illustrated in Fig. 5b. The sensor
Fig. 4. Acetone-sensing properties of the samples treated for 24 h (a), 48 h (b), 72 h (c), 96 h (d), and 120 h (e) at the operating temperature of 200e360 C. The concentration of
acetone is 500 ppm.
Fig. 5. Influence of gas (acetone, ethanol, and LPG) concentration on the sensor response of the sample treated for 96 h (a). A linear fit of the sensor response to the concentration of
the injected gases (b). The operating temperature is 320 C, and a is the slope of the fitting line.
30
- V.X. Hien, L.H. Phuoc, C.T. Khoa et al. Journal of Science: Advanced Materials and Devices 6 (2021) 27e32
response varies linearly with the concentration of the target gases. [3] M. Muruganandham, R. Amutha, M. Sathish, T.S. Singh, R.P.S. Suri,
M. Sillanp€ a, Facile fabrication of hierarchical a-Fe2O3 : self-assembly and its
a€
The highest coefficient of determination (R-square) reaches 99.6%
magnetic and electrochemical properties, J. Phys. Chem. C 115 (2011)
for the linear function of the acetone sensing data. 18164e18173, https://doi.org/10.1021/jp205834m.
Table S1 shows a comparison of the acetone-sensing perfor- [4] L. Jia, K. Harbauer, P. Bogdanoff, K. Ellmer, S. Fiechter, Sputtering deposition of
mance of recent nanomaterials. However, this comparison is not ultra-thin a-Fe2O3 films for solar water splitting, J. Mater. Sci. Technol. 31
(2015) 655e659, https://doi.org/10.1016/j.jmst.2014.10.007.
entirely accurate, because the parameters of a gas sensor depend [5] S. Park, S. Lim, H. Choi, Chemical vapor deposition of iron and iron oxide thin
significantly on the setting of the system (e.g. static or dynamic films from Fe(II) dihydride complexes, Chem. Mater. 18 (2006) 5150e5152,
measurement, gas flow rate, chamber volume, and whether the gas https://doi.org/10.1021/cm0601990.
[6] E. Darezereshki, Synthesis of maghemite (g-Fe2O3) nanoparticles by wet
duct is exposed to the material membrane). The results indicate chemical method at room temperature, Mater. Lett. 64 (2010) 1471e1472,
that the synthesized bi-phase a-/g-Fe2O3 submicron flowers https://doi.org/10.1016/j.matlet.2010.03.064.
possess the highest response compared with the other acetone- [7] T. Dlugosch, A. Chnani, P. Muralidhar, A. Schirmer, J. Biskupek, S. Strehle,
Thermal oxidation synthesis of crystalline iron-oxide nanowires on low-cost
sensing materials. steel substrates for solar water splitting, Semicond. Sci. Technol. 32 (2017),
084001, https://doi.org/10.1088/1361-6641/aa7593.
4. Conclusion [8] H. Srivastava, A.K. Srivastava, M. Babu, S. Rai, T. Ganguli, Topotaxial growth of
a-Fe2O3 nanowires on iron substrate in thermal annealing method, J. Appl.
Phys. 119 (2016) 244311, https://doi.org/10.1063/1.4954975.
The a-/g-Fe2O3 micro flowers were well synthesized by treating [9] Y. Zhu, C.H. Sow, Hotplate technique for nanomaterials, Cosmos 4 (2008)
iron plates in the NH4OH aqueous solution at 40 C for 72e96 h. The 235e255, https://doi.org/10.1142/S0219607708000354.
[10] L. Liao, Z. Zheng, B. Yan, J.X. Zhang, H. Gong, J.C. Li, C. Liu, Z.X. Shen, T. Yu,
flower petals were obtained in form of nanoplates with thicknesses
Morphology controllable synthesis of a-Fe2O3 1D nanostructures: growth
of ~40 nm and ~70 nm in the samples treated for 72 h and 96 h, mechanism and nanodevice based on single nanowire, J. Phys. Chem. C 112
respectively. The uniformity of the submicron flowers and the (2008) 10784e10788, https://doi.org/10.1021/jp802968a.
[11] V.X. Hien, D.D. Vuong, N.D. Chien, Y.-W. Heo, Shape-controlled synthesis of
nanoplates were improved as the treatment time increased up to
Ni(OH)2/NiO nanowalls by surface reaction of Ni foil in aqueous NH4OH,
96 h. For the 120 h treatment time, the ageing effect apparently Mater. Chem. Phys. 217 (2018) 74e81, https://doi.org/10.1016/
occurred, causing the sample morphology to become less uniform J.MATCHEMPHYS.2018.06.054.
and to include many microspheres. The acetone-sensing properties [12] V.X. Hien, N.H. Minh, D.T. Son, N.T. Nghi, L.H. Phuoc, C.T. Khoa, D.D. Vuong,
N.D. Chien, Y.-W. Heo, Acetone sensing properties of CuO nanowalls synthe-
of the annealed samples were investigated at 200e360 C. The sized via oxidation of Cu foil in aqueous NH4OH, Vacuum 150 (2018)
optimal working temperature for all samples was 320 C. The 129e135, https://doi.org/10.1016/j.vacuum.2018.01.030.
sample treated for 96 h showed the best performance among all [13] T. Soejima, K. Takada, S. Ito, Alkaline vapor oxidation synthesis and elec-
trocatalytic activity toward glucose oxidation of CuO/ZnO composite
samples, in which the sensor response to 500 ppm acetone, the nanoarrays, Appl. Surf. Sci. 277 (2013) 192e200, https://doi.org/10.1016/j.
response time and the recovery time were approximately 95, 25 s, apsusc.2013.04.024.
and 25 s, respectively. These sensing data are higher than those of [14] G. Kaur, K. Saini, A.K. Tripathi, V. Jain, D. Deva, I. Lahiri, Room temperature
growth and field emission characteristics of CuO nanostructures, Vacuum 139
the available acetone-sensing materials. Hence, the bi-phase a-/g- (2017) 136e142, https://doi.org/10.1016/j.vacuum.2017.02.020.
Fe2O3 submicron flowers have potential for practical acetone sensor [15] A. Mirzaei, B. Hashemi, K. Janghorban, a-Fe2O3 based nanomaterials as gas
applications. sensors, J. Mater. Sci. Mater. Electron. 27 (2016) 3109e3144, https://doi.org/
10.1007/s10854-015-4200-z.
[16] C.M. Hung, N.D. Hoa, N. Van Duy, N. Van Toan, D.T.T. Le, N. Van Hieu,
Declaration of competing interest Synthesis and gas-sensing characteristics of a-Fe2O3 hollow balls, J. Sci.
Adv. Mater. Devices. 1 (2016) 45e50, https://doi.org/10.1016/j.jsamd.
2016.03.003.
The authors declare that they have no known competing
[17] N.D. Cuong, D.Q. Khieu, T.T. Hoa, D.T. Quang, P.H. Viet, T.D. Lam, N.D. Hoa,
financial interests or personal relationships that could have N. Van Hieu, Facile synthesis of a-Fe2O3 nanoparticles for high-performance
appeared to influence the work reported in this paper. CO gas sensor, Mater. Res. Bull. 68 (2015) 302e307, https://doi.org/10.1016/
j.materresbull.2015.03.069.
[18] G.-J. Sun, H. Kheel, J.K. Lee, S. Choi, S. Lee, C. Lee, H 2S gas sensing properties
Acknowledgments of Fe2O3 nanoparticle-decorated NiO nanoplate sensors, Surf. Coating.
Technol. 307 (2016) 1088e1095, https://doi.org/10.1016/j.surfcoat.2016.
This research is funded by the Vietnam National Foundation for 06.066.
[19] J. Wang, X. Zhang, W. Xu, L. Chen, X. Huang, J. Liu, Effect of facets of a- Fe2O3
Science and Technology Development (NAFOSTED), under grant nanostructures on gas-sensing performance, in: 2013 IEEE Int. Conf. Green
number 103.02-2016.20. We also thank to the NAFOSTED under Comput. Commun. IEEE Internet Things IEEE Cyber, Phys. Soc. Comput.,
grant number of 103.02-2019.25 for additional experiments and IEEE, 2013, pp. 1688e1691, https://doi.org/10.1109/GreenCom-iThings-
CPSCom.2013.309.
spelling correction to complete this study. [20] Y. Tao, Q. Gao, J. Di, X. Wu, Gas sensors based on a-Fe2O3 nanorods, nanotubes
and nanocubes, J. Nanosci. Nanotechnol. 13 (2013) 5654e5660, https://
Appendix A. Supplementary data doi.org/10.1166/jnn.2013.7559.
[21] N. Barsan, D. Koziej, U. Weimar, Metal oxide-based gas sensor research: how
to? Sensor. Actuator. B Chem. 121 (2007) 18e35, https://doi.org/10.1016/
Supplementary data to this article can be found online at j.snb.2006.09.047.
https://doi.org/10.1016/j.jsamd.2020.09.011. [22] J. Ming, Y. Wu, L. Wang, Y. Yu, F. Zhao, CO2-assisted template synthesis of
porous hollow bi-phase g-/a-Fe2O3 nanoparticles with high sensor prop-
erty, J. Mater. Chem. 21 (2011) 17776e17782, https://doi.org/10.1039/
References c1jm12879e.
[23] S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L. Vander Elst, R.N. Muller,
[1] Y. Huang, J. Yao, Y. Zheng, R. Huang, Y. Li, A simple preparation of rod-like Magnetic iron oxide nanoparticles: synthesis, stabilization, vectorization,
Fe2O3 with superior lithium storage performance, Mater. Lett. 234 (2019) physicochemical characterizations and biological applications, Chem. Rev. 108
105e108, https://doi.org/10.1016/j.matlet.2018.09.080. (2008) 2064e2110, https://doi.org/10.1021/cr068445e.
[2] S. Han, L. Hu, Z. Liang, S. Wageh, A.A. Al-Ghamdi, Y. Chen, X. Fang, One-step [24] R. Suresh, K. Giribabu, R. Manigandan, A. Vijayaraj, R. Prabu, A. Stephen,
hydrothermal synthesis of 2D hexagonal nanoplates of a-Fe2O3/graphene V. Narayanan, a-Fe2O3 nanoflowers: synthesis, characterization, electro-
composites with enhanced photocatalytic activity, Adv. Funct. Mater. 24 chemical sensing and photocatalytic property, J. Iran. Chem. Soc. 11 (2014)
(2014) 5719e5727, https://doi.org/10.1002/adfm.201401279. 645e652, https://doi.org/10.1007/s13738-013-0335-0.
31
- V.X. Hien, L.H. Phuoc, C.T. Khoa et al. Journal of Science: Advanced Materials and Devices 6 (2021) 27e32
[25] J. Hasanzadeh, Y. Azizian-Kalandaragh, A. Khodayari, Preparation of a-Fe2O3 [29] C. Yang, X. Su, J. Wang, X. Cao, S. Wang, L. Zhang, Facile microwave-assisted
nanostructures via simple ultrasound-assisted method, J. Optoelectron. Adv. hydrothermal synthesis of varied-shaped CuO nanoparticles and their gas
Mater. 14 (2012) 6e473. sensing properties, Sensor. Actuator. B Chem. 185 (2013) 159e165, https://
[26] A. Bielan ski, J. Haber, Oxygen in catalysis on transition metal oxides, Catal. doi.org/10.1016/j.snb.2013.04.100.
Rev. 19 (1979) 1e41, https://doi.org/10.1080/03602457908065099. [30] X. Han, M. Jin, S. Xie, Q. Kuang, Z. Jiang, Y. Jiang, Z. Xie, L. Zheng,
[27] R. Xu, L.X. Zhang, M.W. Li, Y.Y. Yin, J. Yin, M.Y. Zhu, J.J. Chen, Y. Wang, L.J. Bie, Synthesis of tin dioxide octahedral nanoparticles with exposed
Ultrathin SnO2 nanosheets with dominant high-energy {001} facets for low high-energy {221} facets and enhanced gas-sensing properties, Angew.
temperature formaldehyde gas sensor, Sensor. Actuator. B Chem. (2019) Chem. Int. Ed. 48 (2009) 9180e9183, https://doi.org/10.1002/anie.
186e194, https://doi.org/10.1016/j.snb.2019.03.012. 200903926.
[28] S. Capone, M.G. Manera, A. Taurino, P. Siciliano, R. Rella, S. Luby, [31] M. Jiao, N.V. Chien, N. Van Duy, N.D. Hoa, N. Van Hieu, K. Hjort, H. Nguyen, On-
M. Benkovicova, P. Siffalovic, E. Majkova, Fe3O4/g-Fe2O3 nanoparticle multi- chip hydrothermal growth of ZnO nanorods at low temperature for highly
layers deposited by the Langmuir-blodgett technique for gas sensors appli- selective NO2 gas sensor, Mater. Lett. 169 (2016) 231e235, https://doi.org/
cation, Langmuir 30 (2014) 1190e1197, https://doi.org/10.1021/la404542u. 10.1016/j.matlet.2016.01.123.
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