Please cite this article in press as: N.T.A. Thu, et al., Fe
2
O
3
nanoporous network fabricated from Fe
3
O
4
/reduced graphene oxide for
high-performance ethanol gas sensor, Sens. Actuators B: Chem. (2017), https://doi.org/10.1016/j.snb.2017.09.154
ARTICLE IN PRESS
G Model
SNB-23245; No. of Pages 9
Sensors and Actuators B xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Sensors and Actuators B: Chemical
journal homepage: www.elsevier.com/locate/snb
Research Paper
Fe
2
O
3
nanoporous network fabricated from Fe
3
O
4
/reduced graphene
oxide for high-performance ethanol gas sensor
Nguyen Thi Anh Thu
a
, Nguyen Duc Cuong
b,c,∗
, Le Cao Nguyen
a
, Dinh Quang Khieu
b
,
Pham Cam Nam
d
, Nguyen Van Toan
e
, Chu Manh Hung
e
, Nguyen Van Hieu
e,∗∗
a
University of Education, Hue University, 34 Le Loi, Hue City, Viet Nam
b
Hue University of Sciences, Hue University, 77 Nguyen Hue, Hue City, Viet Nam
c
School of Hospitality and Tourism, Hue University, 22 Lam Hoang, Hue City, Viet Nam
d
Department of Chemistry, The University of Danang, Danang University of Science and Technology, 54 Nguyen Luong Bang, Lien Chieu, Da Nang, Viet Nam
e
International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi, Viet Nam
a r t i c l e i n f o
Article history:
Received 22 June 2017
Received in revised form 29 August 2017
Accepted 22 September 2017
Available online xxx
Keywords:
Fe3O4/reduced graphene oxide
-Fe2O3 nanoporous network
Gas sensor
Ethanol
a b s t r a c t
Nanoporous network metal oxides are potential candidates for various applications such as filtration, bio-
materials devices, and sensing materials. The present work focused on the simple and scalable fabrication
of the -Fe
2
O
3
nanoporous network for ethanol gas sensor using Fe
3
O
4
/reduced graphene oxide (rGO) as
a precursor. The analyzed morphology and crystal structure indicated that the -Fe
2
O
3
nanoporous net-
work was formed due to some factors during thermal procedures such as the phase transformation from
magnetite to hematite, nanoparticle agglomeration, and combustion of rGO. The ethanol gas-sensing
properties of the -Fe
2
O
3
nanoporous network were investigated. The response to 100 ppm ethanol gas
was as high as 9.5, while the cross-gas responses to 100 ppm NH
3
, H
2
, and CO gases were all lower than
2.0. These values indicated a good selectivity of the sensors. Furthermore, the 90% response times to
ethanol gas were less than 5 s at 400
◦
–450
◦
C. The proposed strategy has potential in the preparation of
other porous network metal oxides to achieve high-performance gas sensors.
© 2017 Elsevier B.V. All rights reserved.
1. Introduction
Gas sensors have broad applications in homeland security,
industrial safety, automobiles, medical diagnosis, and environ-
mental monitoring [1]. Among many gas detection technologies,
semiconducting metal oxide-based gas sensors are widely used in
the gas detection market due to their high sensitivity, fast response,
and simple device structures that enable portable applications [2,3].
The fundamental detection mechanism can be explained by the the-
ory that changes in resistance of semiconducting metal oxides are
caused by the adsorption of oxygen and reaction with target gas
molecules [4]. Therefore, the performance of these sensors based
on semiconducting metal oxides is highly related to their size,
shape, and surface conditions [5]. Recent efforts have focused on the
design and development of new structures for effective gas sensor
∗
Corresponding author at: University of Sciences,Hue University, 77 Nguyen Hue,
Hue City, Viet Nam.
∗∗
Corresponding author at: International Training Institute for Materials Science,
Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi, Viet Nam.
E-mail addresses: nguyenduccuong@hueuni.edu.vn (N.D. Cuong),
hieu@itims.edu.vn, hieu.nguyenvan@hust.edu.vn (N.V. Hieu).
applications, in which the control of a proper geometrical morphol-
ogy of semiconducting metal oxides with porous structures is an
important aspect for enhancing gas-sensing performance; these
metal oxides possess superior gas-sensing performance [6–9].
Porous structures enable rapid gas diffusion inside the sensing
material, and its high surface area increases the adsorption sites,
which result in rapid gas response and enhanced gas sensitivity
[10].
Among the transition metal oxides, hematite (-Fe
2
O
3
), the
most stable iron oxide phase under ambient conditions with band
gap (E
g
) of 2.1 eV, is particularly attractive for gas sensors, catalysis,
lithium-ion batteries, optical devices, and pigments because of its
high chemical stability, low cost, nontoxicity, and high resistance
to corrosion [11,12]. For gas-sensing applications, various -Fe
2
O
3
nanostructures are efficient gas-sensing materials due to their high
surface-to-volume ratio and fast mass transport [13]. The sensors
based on porous -Fe
2
O
3
nanostructures often exhibit superior
gas-sensing properties as a result of their porous structures and
high surface areas [14]. Wang et al. [15] showed that porous a-
Fe
2
O
3
nanoshuttles exhibit excellent gas-sensing performance to
toluene with good reproducibility and short response–recovery
time. Huang et al. [16] synthesized porous Fe
2
O
3
nanoparticles
https://doi.org/10.1016/j.snb.2017.09.154
0925-4005/© 2017 Elsevier B.V. All rights reserved.