| Summary: | This paper reports a study on the enhanced H<sub>2</sub> selectivity of SnO<sub>2</sub> gas sensors with SiO<sub>2</sub> on the surface of the sensors obtained via chemical vapor deposition using dirthoxydimethylsilane as the Si source. The gas sensors were tested for sensing performance towards ethanol, acetone, benzene, and hydrogen at operating temperatures from 150 °C to 400 °C. Our experimental results show that higher selectivity and responses to hydrogen were achieved by the deposition of SiO<sub>2</sub> on the surface of the sensors. The sensor with SiO<sub>2</sub> deposited on its surface at 500 °C for 8 h exhibited the highest response (R<sub>a</sub>/R<sub>g</sub> = 144) to 1000 ppm hydrogen at 350 °C, and the sensor with SiO<sub>2</sub> deposited on its surface at 600 °C for 4 h attained the maximum response variation coefficient (D = 69.4) to 1000 ppm hydrogen at 200 °C. The mechanism underlying the improvement in sensitivity and the higher responses to hydrogen in the sensors with SiO<sub>2</sub> on their surface is also discussed.
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