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Sensors and Actuators B: Chemical
journal homepage: www.elsevier.com/locate/snb
Ultra-sensitive sensing platform based on Pt-ZnO-In
2
O
3
nanofibers for
detection of acetone
Lanlan Guo, Fang Chen, Ning Xie, Xueying Kou, Chong Wang, Yanfeng Sun
⁎
, Fangmeng Liu,
Xishuang Liang, Yuan Gao, Xu Yan, Tong Zhang, Geyu Lu
⁎
State Key Laboratory on Integrated Optoelectronics, Key Laboratory of Gas Sensors, Jilin Province and College of Electronic Science and Engineering, Jilin University, 2699
Qianjin Street, Changchun, 130012, People’s Republic of China
ARTICLE INFO
Keywords:
Pt@ZIF-8
Electrospinning
Acetone
Pt-ZnO-In
2
O
3
nanofibers
ABSTRACT
Ultra-small Pt nanoparticles functionalized In
2
O
3
nanofibers have been designed by using a new catalyst loading
platform (Pt@ZIF-8), which involves three steps including the synthesis of ZIF-8 nanoparticles, the preparation
of Pt@ZIF-8 and the subsequent transformation to Pt-ZnO-In
2
O
3
composite nanofibers by electrospinning. The
experimental results demonstrate that the average sizes of Pt nanoparticles obtained in this way are only ∼3 nm,
which is helpful to obtain highly sensitive gas sensors due to the ultra-small Pt nanoparticles. Gas sensing
investigations indicate that the sensor based on Pt-ZnO-In
2
O
3
nanofibers exhibit the superior acetone response
(R
a
/R
g
= 57.1 to 100 ppm at 300 °C), ultra-fast response and recovery time (1/44s) and low detection limit
(0.5 ppm). In this study, the excellent acetone gas sensing property of Pt-ZnO-In
2
O
3
nanofibers attributes to the
chemical sensitization and electrical sensitization of the ultra-small Pt nanoparticles, the n-n heterojunctions
between ZnO and In
2
O
3
, and the p-n heterojunction produced between p-type PtO
2
and n-type In
2
O
3
(ZnO).
1. Introduction
Nowadays the air pollution is becoming more and more serious and
the volatile organic compounds are the most common air pollutants in
the atmosphere. Among them, acetone, an important organic synthetic
raw material, is extremely flammable and has irritation to the eyes,
nose and throat [1]. Gas sensors based on metal oxides, as a device with
high reliability, good selectivity, high sensitivity and low power con-
sumption, have been widely used in our daily life. As reported before,
many acetone gas sensors based on metal oxides have been fabricated
[2–8]. Among these metal oxides, In
2
O
3
has been regarded as a pro-
mising functional sensitive material because of its wide band gap of
3.55–3.75 eV at room temperature [9]. It is well known that the
properties of metal-oxide semiconductors (MOS) can be greatly im-
proved by simple surface modification with noble metals [10] . For
example, Wang and his co-workers have reported that In
2
O
3
porous
nanocubes loaded by Au nanoparticles (NPs) display enhanced sensing
performance towards formaldehyde [11]. High performance methanol
gas sensors based on palladium-platinum-In
2
O
3
composited nanocrys-
talline SnO
2
have been also fabricated [12]. These researches verify
that the noble metals in such materials act as catalysts indeed can im-
prove the gas sensing performance of the metal oxide semiconductors.
However, some disadvantages still exist. First, the sizes of the noble
metal nanoparticles obtained in the literatures above are larger than
5 nm. Second, the agglomeration of the catalysts will produce in these
researches above, and signifi cantly weaken the performance of the gas
sensors. As is well known, smaller noble metal particles combined with
MOS will lead to better gas sensitivity. Therefore, finding a new method
to get ultra-small noble metal nanoparticles and then to make them
disperse well in metal oxides is imperative.
Metal–organic frameworks (MOFs, also known as porous coordina-
tion polymers) are an emerging class of porous materials constructed
from metal containing nodes and organic linkers [13]. MOFs have
drawn researchers' attention all along due to their excellent properties
such as ultra-high porosity, incredibly high surface area and tunable
structures [14]. To make full use of their unique characteristic, MOFs
have important applications in hydrogen storage [15], gas adsorption
and separation [16–18], drug release [19] and catalysis [20]. Besides,
another striking feature of MOFs is that noble metal nanoparticles can
be encapsulated in the cavities of the MOFs. Because the noble metal
catalyst nanoparticles are embedded in the cavity of MOF, the size of
these nanoparticles can be limited to ultra-small nanometers. Zeolite
imidazole framework-8 (ZIF-8) is one of the most attractive MOFs due
to its facile synthesis methods [21,22]. As reported, Huo et al. used
surfactants (PVP) for the controlled encapsulation of Au and Pt catalysts
into ZIF-8 [23]. In terms of gas sensing, Kim et al. proposed the
https://doi.org/10.1016/j.snb.2018.05.161
Received 28 February 2018; Received in revised form 25 May 2018; Accepted 27 May 2018
⁎
Corresponding authors.
E-mail addresses: syf@jlu.edu.cn (Y. Sun), lugy@jlu.edu.cn (G. Lu).
Sensors & Actuators: B. Chemical 272 (2018) 185–194
Available online 29 May 2018
0925-4005/ © 2018 Published by Elsevier B.V.
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