The
application of metal oxide-based sensors for the detection
of volatile organic compounds is restricted because of their high
operating temperatures and poor gas sensing selectivity. Driven by
this fact, we report the low operating temperature and high performance
of C
3
H
7
OH and C
2
H
5
OH sensors.
The sensors comprising SnO
2
hollow spheres, nanoparticles,
nanorods, and fishbones with tunable morphologies were synthesized
with a simple hydrothermal one-pot method. The SnO
2
hollow
spheres demonstrated the highest sensing response (resistance ratio
of 20) toward C
3
H
7
OH at low operating temperatures
(75 °C) compared to other tested interference vapors and gases,
such as C
3
H
5
O, C
2
H
5
OH,
CO, NH
3
, CH
4
, and NO
2
. This improved
response can be associated with the higher surface area and intrinsic
point defects. At a higher operating temperature of 150 °C, a
response of 28 was witnessed for SnO
2
nanorods. A response
of 59 was observed for SnO
2
nanoparticle-based sensor toward
C
2
H
5
OH at 150 °C. This variation in the
optimal temperature with respect to variations in the sensor morphology
implies that the vapor selectivity and sensitivity are morphology-dependent.
The relation between the intrinsic sensing performance and vapor selectivity
originated from the nonstoichiometry of SnO
2
, which resulted
in excess oxygen vacancies (V
O
) and higher surface areas.
This characteristic played a vital role in the enhancement of the
target gas absorptivity and the charge transfer capability of SnO
2
hollow sphere-based sensor.
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