Ultrafast response and recovery trimethylamine sensor based on
a
-Fe
2
O
3
snowflake-like hierarchical architectures
Tianye Yang
a
, Liyong Du
a
, Chengbo Zhai
a
, Zhifang Li
a
, Qi Zhao
a
, Yang Luo
a
,
Dejun Xing
b
,
**
, Mingzhe Zhang
a
,
*
a
State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, People's Republic of China
b
Department of Medical Oncology, Jilin Cancer Hospital, 1018 Huguang Road, Changchun, Jilin, 130012, People's Republic of China
article info
Article history:
Received 10 April 2017
Received in revised form
11 May 2017
Accepted 20 May 2017
Available online 22 May 2017
Keywords:
Fe
2
O
3
Hierarchical architectures
TMA
Fast response and recovery
Gas sensor
abstract
Snowflake-like
a
-Fe
2
O
3
hierarchical architectures have been developed to detect trimethylamine (TMA)
gas. The
a
-Fe
2
O
3
has been synthesized by using a facile solvothermal method and a subsequent
annealing process. As-fabricated snowflake-like
a
-Fe
2
O
3
based sensor exhibits ultrafast response and
recovery time (0.9 s/1.5 s), excellent selectivity, high response, and superior repeatability toward TMA
gas. XPS, PL and UV indicates that abundant oxygen vacancies exist in the
a
-Fe
2
O
3
surfaces. Oxygen
vacancies provide essential active sites for gas adsorption which enormously improve the ability of
electron transfer. The remarkable TMA sensing performance can be attributed to the cooperation of
oxygen vacancies providing more active sites, rapid electron exchange between Fe
3þ
and Fe
2þ
cations
inducing conductivity greatly change, and unique snowflake-like hierarchical structure possessing large
contacting area and monocrystalline feature. Such novel snowflake-like
a
-Fe
2
O
3
hierarchical architec-
tures will be a promising candidate for TMA, fish and sea-food freshness detection.
© 2017 Elsevier B.V. All rights reserved.
1. Introduction
Marine products and fishes are extensively demanded all
around the world because they are important biological sources
containing valuable proteins, fats, and fat-soluble vitamins for hu-
man beings. However, consumption of stale seafood can lead to
serious health issues such as gastroenteritis and septicemia [1].Itis
important to detect fish freshness in consideration of food safety
issue. As for fish freshness detection, the most widely applied
method is based on the chemical analysis of decomposition prod-
ucts from adenosine triphosphate (ATP)-related compounds in the
tissue of fish. However, it is inevitable to require complicated and
time-consuming work [2e4]. Therefore, it is essential and urgent to
develop a reliable, fast, continuous, nondestructive and accurate
analytical method for evaluating fish freshness.
Trimethylamine (TMA) is a basic tertiary amine compound with
the formula N(CH
3
)
3
and is also a pungent gas secreted from dead
fish. The content of TMA gas increases rapidly as the fish begins to
deteriorate [5]. Based on this feature, TMA can be used as an
effective indicator of seafood quality to evaluate the freshness of
fish. In the evaluation of fish freshness, 0e10 ppm TMA is regarded
as fresh, 10e50 ppm is preliminary rot, and over 60 ppm is putrid
and inedible [6,7]. In addition, exposure to TMA vapor would cause
headaches, nausea, and irritation to the eyes as well as to the res-
piratory system, so the allowable limit set by the National Institute
for Occupational Safety and Health in USA is 10 ppm for 10 h [8,9].
Hence, the detection and control of TMA are very important and
several detecting methods of TMA gas have been presented,
including ion mobility spectrometry, high performance liquid
chromatography, gas chromatography, mass spectrometry, and the
use of a quartz microbalance [10e14]. Nevertheless, the afore-
mentioned methods usually require complicated equipment, a long
sample preparation time, and professional operating skills. It is
necessary to develop highly sensitive, fast response and recovery
gas sensors for accomplishing rapid, reliable, nondestructive, and
real-time detection of trace TMA gas [15].
Among a variety of gas sensitive materials, metal oxide semi-
conductors (MOS) have been extensively investigated. They are
usually recognized as the most economic materials as gas sensors
and have many advantages, such as high sensitivity, fast response
* Corresponding author.
** Corresponding author.
E-mail addresses: xdejun111162@sohu.com (D. Xing), zhangmz@jlu.edu.cn
(M. Zhang).
Contents lists available at ScienceDirect
Journal of Alloys and Compounds
journal homepage: http://www.elsevier.com/locate/jalcom
http://dx.doi.org/10.1016/j.jallcom.2017.05.227
0925-8388/© 2017 Elsevier B.V. All rights reserved.
Journal of Alloys and Compounds 718 (2017) 396e404