Development Of Nanocasted Tin Oxide For Ethanol And Acetone Gas Sensor
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Date
2018-09-01
Authors
Juhari, Jusliha
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The understanding of sensing behaviour of most portable gas sensors available
in the market is still limited. This research study aimed at the development of
nanocasted mesoporous tin oxide (SnO2) for ethanol and acetone gas sensors. To
achieve this goal, ordered mesoporous SnO2 materials were prepared by means of a
nanocasting method using pre-synthesized ordered mesoporous silica (OMS) as hard
templates. Effects of nanocasting parameters on the formation, structural and textural
properties of ordered mesoporous SnO2, as well the ability to detect ethanol vapour
were studied by employing the one-factor-at-a-time method. The thermal stability of
ordered mesoporous SnO2 was also investigated for different calcination temperatures.
The fabricated sensors in the form of thick-film configuration of ordered mesoporous
SnO2 were further tested for ethanol vapour detection at operating temperatures
between 150 °C and 400 °C. The sensing performance of the fabricated sensors was
maximized under various operating parameters. It was found that all nanocasted
mesoporous SnO2 materials exhibited well-defined, ordered mesostructured, and large
specific surface area as well as high crystalline frameworks, indicating successful
replication from the OMS templates. The best sensor produced was S(K80)-
VASEM(2) with maximum sensitivity of ~28.15 towards 1000 ppm ethanol at an
operating temperature of 300 °C. The sensitivity of S(K80)-VASEM(2) sensor was
further enhanced by loading 5.0 weight% of basic oxide (La2O3) into SnO2 through
direct synthesis that gave the highest sensitivity of ~52.57. The basic oxide could help
the formation of ordered and stable mesoporous networks, high crystalline
frameworks, large surface areas and the presence of basic sites. These factors increased
the interaction between the ethanol molecules and the surface active sites of the SnO2
sensor. It also increased the selectivity in ethanol oxidation reaction that increased the
dehydrogenation process. The 5.0LS(K80)-V(2)-DS sensor exhibited a moderate
response time of 52 s and a short recovery time of 43 s as well as good selectivity to
ethanol over acetone vapour. This sensor also demonstrated high stability,
repeatability and reliable sensitivity after continuous use for 14 days. All the results
showed that the nanocasting method is an effective and a simple way to prepare
ordered mesoporous SnO2 materials with unique and enhanced structural and textural
properties. The produced sensors also displayed excellent gas sensing performances in
detecting ethanol vapour.