| Summary: | 碩士 === 元智大學 === 化學工程與材料科學學系 === 96 === The objectives of this study are two-fold: (1) the preparation of tin oxide (SnO2) nanoparticles and (2) the preparation of prototype SnO2-based sensors. The first part is involved with the preparation and characterization of SnO2 nanoparticles. Experimental parameters include fuel/gas ratio, pressure of reaction chamber, and synthesis time. XRD results suggest rutile phase SnO2 nanoparticles in 18-33nm range can be produced under oxygen excess condition. It was also found that the grain size increases with increasing chamber pressure. TEM result shows particle morphology is a function of all three parameters. A shorter synthesis time yields more spherical and uniformly-sized tin oxide nanoparticles, while a longer synthesis time leads to non-uniformly-sized nanoparticles in a wide variety of shapes, possibly due to extensive radiative heating of the flame over the deposited nanoparticle layer.
The second part of this study is involved with the preparation of prototype nano- SnO2 gas sensors using the flame derived tin oxide nanoparticles and their sensing performance towards carbon monoxide gas (mixed with air) in 100-500ppm range. Six types of sensors were prepared. They are: sensor prepared with SnO2 (as-derived), SnO2 (sintered), nano-Pt sputtered on SnO2 (as-derived), nano-Pt sputtered on SnO2 (sintered), nano-Au sputtered on SnO2 (as-derived), and nano-Au sputtered on SnO2 (sintered). Preliminary results showed particle size is subject to change under the sensing temperature used in this study, which leads to unstable and non-linear sensor response. After proper post-heat treatment of the flame-derived SnO2 particles and pre-conditioning the sensor modules, all sensors exhibited a repeatable, linear relationship between sensor conductance and CO concentration.
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